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rfc:rfc2459

Network Working Group R. Housley Request for Comments: 2459 SPYRUS Category: Standards Track W. Ford

                                                              VeriSign
                                                               W. Polk
                                                                  NIST
                                                               D. Solo
                                                              Citicorp
                                                          January 1999
              Internet X.509 Public Key Infrastructure
                    Certificate and CRL Profile

Status of this Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

 This memo profiles the X.509 v3 certificate and X.509 v2 CRL for use
 in the Internet.  An overview of the approach and model are provided
 as an introduction.  The X.509 v3 certificate format is described in
 detail, with additional information regarding the format and
 semantics of Internet name forms (e.g., IP addresses).  Standard
 certificate extensions are described and one new Internet-specific
 extension is defined.  A required set of certificate extensions is
 specified.  The X.509 v2 CRL format is described and a required
 extension set is defined as well.  An algorithm for X.509 certificate
 path validation is described. Supplemental information is provided
 describing the format of public keys and digital signatures in X.509
 certificates for common Internet public key encryption algorithms
 (i.e., RSA, DSA, and Diffie-Hellman).  ASN.1 modules and examples are
 provided in the appendices.
 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in RFC 2119.

Housley, et. al. Standards Track [Page 1] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 Please send comments on this document to the ietf-pkix@imc.org mail
 list.
                         TTTTaaaabbbblllleeee ooooffff CCCCoooonnnntttteeeennnnttttssss
 1  Introduction ................................................    5
 2  Requirements and Assumptions ................................    6
 2.1  Communication and Topology ................................    6
 2.2  Acceptability Criteria ....................................    7
 2.3  User Expectations .........................................    7
 2.4  Administrator Expectations ................................    7
 3  Overview of Approach ........................................    7
 3.1  X.509 Version 3 Certificate ...............................    9
 3.2  Certification Paths and Trust .............................   10
 3.3  Revocation ................................................   12
 3.4  Operational Protocols .....................................   13
 3.5  Management Protocols ......................................   13
 4  Certificate and Certificate Extensions Profile ..............   15
 4.1  Basic Certificate Fields ..................................   15
 4.1.1  Certificate Fields ......................................   16
 4.1.1.1  tbsCertificate ........................................   16
 4.1.1.2  signatureAlgorithm ....................................   16
 4.1.1.3  signatureValue ........................................   17
 4.1.2  TBSCertificate ..........................................   17
 4.1.2.1  Version ...............................................   17
 4.1.2.2  Serial number .........................................   18
 4.1.2.3  Signature .............................................   18
 4.1.2.4  Issuer ................................................   18
 4.1.2.5  Validity ..............................................   21
 4.1.2.5.1  UTCTime .............................................   22
 4.1.2.5.2  GeneralizedTime .....................................   22
 4.1.2.6  Subject ...............................................   22
 4.1.2.7  Subject Public Key Info ...............................   23
 4.1.2.8  Unique Identifiers ....................................   24
 4.1.2.9 Extensions .............................................   24
 4.2  Certificate Extensions ....................................   24
 4.2.1  Standard Extensions .....................................   25
 4.2.1.1  Authority Key Identifier ..............................   25
 4.2.1.2  Subject Key Identifier ................................   26
 4.2.1.3  Key Usage .............................................   27
 4.2.1.4  Private Key Usage Period ..............................   29
 4.2.1.5  Certificate Policies ..................................   29
 4.2.1.6  Policy Mappings .......................................   31
 4.2.1.7  Subject Alternative Name ..............................   32

Housley, et. al. Standards Track [Page 2] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 4.2.1.8  Issuer Alternative Name ...............................   34
 4.2.1.9  Subject Directory Attributes ..........................   34
 4.2.1.10  Basic Constraints ....................................   35
 4.2.1.11  Name Constraints .....................................   35
 4.2.1.12  Policy Constraints ...................................   37
 4.2.1.13  Extended key usage field .............................   38
 4.2.1.14  CRL Distribution Points ..............................   39
 4.2.2  Private Internet Extensions .............................   40
 4.2.2.1  Authority Information Access ..........................   41
 5  CRL and CRL Extensions Profile ..............................   42
 5.1  CRL Fields ................................................   43
 5.1.1  CertificateList Fields ..................................   43
 5.1.1.1  tbsCertList ...........................................   44
 5.1.1.2  signatureAlgorithm ....................................   44
 5.1.1.3  signatureValue ........................................   44
 5.1.2  Certificate List "To Be Signed" .........................   44
 5.1.2.1  Version ...............................................   45
 5.1.2.2  Signature .............................................   45
 5.1.2.3  Issuer Name ...........................................   45
 5.1.2.4  This Update ...........................................   45
 5.1.2.5  Next Update ...........................................   45
 5.1.2.6  Revoked Certificates ..................................   46
 5.1.2.7  Extensions ............................................   46
 5.2  CRL Extensions ............................................   46
 5.2.1  Authority Key Identifier ................................   47
 5.2.2  Issuer Alternative Name .................................   47
 5.2.3  CRL Number ..............................................   47
 5.2.4  Delta CRL Indicator .....................................   48
 5.2.5  Issuing Distribution Point ..............................   48
 5.3  CRL Entry Extensions ......................................   49
 5.3.1  Reason Code .............................................   50
 5.3.2  Hold Instruction Code ...................................   50
 5.3.3  Invalidity Date .........................................   51
 5.3.4  Certificate Issuer ......................................   51
 6  Certificate Path Validation .................................   52
 6.1  Basic Path Validation .....................................   52
 6.2  Extending Path Validation .................................   56
 7  Algorithm Support ...........................................   57
 7.1  One-way Hash Functions ....................................   57
 7.1.1  MD2 One-way Hash Function ...............................   57
 7.1.2  MD5 One-way Hash Function ...............................   58
 7.1.3  SHA-1 One-way Hash Function .............................   58
 7.2  Signature Algorithms ......................................   58
 7.2.1  RSA Signature Algorithm .................................   59
 7.2.2  DSA Signature Algorithm .................................   60
 7.3  Subject Public Key Algorithms .............................   60
 7.3.1  RSA Keys ................................................   61
 7.3.2  Diffie-Hellman Key Exchange Key .........................   61

Housley, et. al. Standards Track [Page 3] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 7.3.3  DSA Signature Keys ......................................   63
 8  References ..................................................   64
 9  Intellectual Property Rights ................................   66
 10  Security Considerations ....................................   67
 Appendix A.  ASN.1 Structures and OIDs .........................   70
 A.1 Explicitly Tagged Module, 1988 Syntax ......................   70
 A.2 Implicitly Tagged Module, 1988 Syntax ......................   84
 Appendix B.  1993 ASN.1 Structures and OIDs ....................   91
 B.1 Explicitly Tagged Module, 1993 Syntax ......................   91
 B.2 Implicitly Tagged Module, 1993 Syntax ......................  108
 Appendix C.  ASN.1 Notes .......................................  116
 Appendix D.  Examples ..........................................  117
 D.1  Certificate ...............................................  117
 D.2  Certificate ...............................................  120
 D.3  End-Entity Certificate Using RSA ..........................  123
 D.4  Certificate Revocation List ...............................  126
 Appendix E.  Authors' Addresses ................................  128
 Appendix F.  Full Copyright Statement ..........................  129

Housley, et. al. Standards Track [Page 4] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

1 Introduction

 This specification is one part of a family of standards for the X.509
 Public Key Infrastructure (PKI) for the Internet.  This specification
 is a standalone document; implementations of this standard may
 proceed independent from the other parts.
 This specification profiles the format and semantics of certificates
 and certificate revocation lists for the Internet PKI.  Procedures
 are described for processing of certification paths in the Internet
 environment.  Encoding rules are provided for popular cryptographic
 algorithms.  Finally, ASN.1 modules are provided in the appendices
 for all data structures defined or referenced.
 The specification describes the requirements which inspire the
 creation of this document and the assumptions which affect its scope
 in Section 2.  Section 3 presents an architectural model and
 describes its relationship to previous IETF and ISO/IEC/ITU
 standards.  In particular, this document's relationship with the IETF
 PEM specifications and the ISO/IEC/ITU X.509 documents are described.
 The specification profiles the X.509 version 3 certificate in Section
 4, and the X.509 version 2 certificate revocation list (CRL) in
 Section 5. The profiles include the identification of ISO/IEC/ITU and
 ANSI extensions which may be useful in the Internet PKI. The profiles
 are presented in the 1988 Abstract Syntax Notation One (ASN.1) rather
 than the 1994 syntax used in the ISO/IEC/ITU standards.
 This specification also includes path validation procedures in
 Section 6.  These procedures are based upon the ISO/IEC/ITU
 definition, but the presentation assumes one or more self-signed
 trusted CA certificates.  Implementations are required to derive the
 same results but are not required to use the specified procedures.
 Section 7 of the specification describes procedures for
 identification and encoding of public key materials and digital
 signatures.  Implementations are not required to use any particular
 cryptographic algorithms.  However, conforming implementations which
 use the identified algorithms are required to identify and encode the
 public key materials and digital signatures as described.
 Finally, four appendices are provided to aid implementers.  Appendix
 A contains all ASN.1 structures defined or referenced within this
 specification.  As above, the material is presented in the 1988
 Abstract Syntax Notation One (ASN.1) rather than the 1994 syntax.
 Appendix B contains the same information in the 1994 ASN.1 notation
 as a service to implementers using updated toolsets.  However,
 Appendix A takes precedence in case of conflict.  Appendix C contains

Housley, et. al. Standards Track [Page 5] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 notes on less familiar features of the ASN.1 notation used within
 this specification.  Appendix D contains examples of a conforming
 certificate and a conforming CRL.

2 Requirements and Assumptions

 The goal of this specification is to develop a profile to facilitate
 the use of X.509 certificates within Internet applications for those
 communities wishing to make use of X.509 technology. Such
 applications may include WWW, electronic mail, user authentication,
 and IPsec.  In order to relieve some of the obstacles to using X.509
 certificates, this document defines a profile to promote the
 development of certificate management systems; development of
 application tools; and interoperability determined by policy.
 Some communities will need to supplement, or possibly replace, this
 profile in order to meet the requirements of specialized application
 domains or environments with additional authorization, assurance, or
 operational requirements.  However, for basic applications, common
 representations of frequently used attributes are defined so that
 application developers can obtain necessary information without
 regard to the issuer of a particular certificate or certificate
 revocation list (CRL).
 A certificate user should review the certificate policy generated by
 the certification authority (CA) before relying on the authentication
 or non-repudiation services associated with the public key in a
 particular certificate.  To this end, this standard does not
 prescribe legally binding rules or duties.
 As supplemental authorization and attribute management tools emerge,
 such as attribute certificates, it may be appropriate to limit the
 authenticated attributes that are included in a certificate.  These
 other management tools may provide more appropriate methods of
 conveying many authenticated attributes.

2.1 Communication and Topology

 The users of certificates will operate in a wide range of
 environments with respect to their communication topology, especially
 users of secure electronic mail.  This profile supports users without
 high bandwidth, real-time IP connectivity, or high connection
 availability.  In addition, the profile allows for the presence of
 firewall or other filtered communication.

Housley, et. al. Standards Track [Page 6] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 This profile does not assume the deployment of an X.500 Directory
 system.  The profile does not prohibit the use of an X.500 Directory,
 but other means of distributing certificates and certificate
 revocation lists (CRLs) may be used.

2.2 Acceptability Criteria

 The goal of the Internet Public Key Infrastructure (PKI) is to meet
 the needs of deterministic, automated identification, authentication,
 access control, and authorization functions. Support for these
 services determines the attributes contained in the certificate as
 well as the ancillary control information in the certificate such as
 policy data and certification path constraints.

2.3 User Expectations

 Users of the Internet PKI are people and processes who use client
 software and are the subjects named in certificates.  These uses
 include readers and writers of electronic mail, the clients for WWW
 browsers, WWW servers, and the key manager for IPsec within a router.
 This profile recognizes the limitations of the platforms these users
 employ and the limitations in sophistication and attentiveness of the
 users themselves.  This manifests itself in minimal user
 configuration responsibility (e.g., trusted CA keys, rules), explicit
 platform usage constraints within the certificate, certification path
 constraints which shield the user from many malicious actions, and
 applications which sensibly automate validation functions.

2.4 Administrator Expectations

 As with user expectations, the Internet PKI profile is structured to
 support the individuals who generally operate CAs.  Providing
 administrators with unbounded choices increases the chances that a
 subtle CA administrator mistake will result in broad compromise.
 Also, unbounded choices greatly complicate the software that shall
 process and validate the certificates created by the CA.

3 Overview of Approach

 Following is a simplified view of the architectural model assumed by
 the PKIX specifications.

Housley, et. al. Standards Track [Page 7] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

     +---+
     | C |                       +------------+
     | e | <-------------------->| End entity |
     | r |       Operational     +------------+
     | t |       transactions          ^
     |   |      and management         |  Management
     | / |       transactions          |  transactions
     |   |                             |                PKI users
     | C |                             v
     | R |       -------------------+--+-----------+----------------
     | L |                          ^              ^
     |   |                          |              |  PKI management
     |   |                          v              |      entities
     | R |                       +------+          |
     | e | <---------------------| RA   | <---+    |
     | p |  Publish certificate  +------+     |    |
     | o |                                    |    |
     | s |                                    |    |
     | I |                                    v    v
     | t |                                +------------+
     | o | <------------------------------|     CA     |
     | r |   Publish certificate          +------------+
     | y |   Publish CRL                         ^
     |   |                                       |
     +---+                        Management     |
                                  transactions   |
                                                 v
                                             +------+
                                             |  CA  |
                                             +------+
                        Figure 1 - PKI Entities
 The components in this model are:
 end entity:  user of PKI certificates and/or end user system that
              is the subject of a certificate;
 CA:          certification authority;
 RA:          registration authority, i.e., an optional system to
              which a CA delegates certain management functions;
 repository:  a system or collection of distributed systems that
              store certificates and CRLs and serves as a means of
              distributing these certificates and CRLs to end
              entities.

Housley, et. al. Standards Track [Page 8] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

3.1 X.509 Version 3 Certificate

 Users of a public key shall be confident that the associated private
 key is owned by the correct remote subject (person or system) with
 which an encryption or digital signature mechanism will be used.
 This confidence is obtained through the use of public key
 certificates, which are data structures that bind public key values
 to subjects.  The binding is asserted by having a trusted CA
 digitally sign each certificate. The CA may base this assertion upon
 technical means (a.k.a., proof of posession through a challenge-
 response protocol), presentation of the private key, or on an
 assertion by the subject.  A certificate has a limited valid lifetime
 which is indicated in its signed contents.  Because a certificate's
 signature and timeliness can be independently checked by a
 certificate-using client, certificates can be distributed via
 untrusted communications and server systems, and can be cached in
 unsecured storage in certificate-using systems.
 ITU-T X.509 (formerly CCITT X.509) or ISO/IEC/ITU 9594-8, which was
 first published in 1988 as part of the X.500 Directory
 recommendations, defines a standard certificate format [X.509]. The
 certificate format in the 1988 standard is called the version 1 (v1)
 format.  When X.500 was revised in 1993, two more fields were added,
 resulting in the version 2 (v2) format. These two fields may be used
 to support directory access control.
 The Internet Privacy Enhanced Mail (PEM) RFCs, published in 1993,
 include specifications for a public key infrastructure based on X.509
 v1 certificates [RFC 1422].  The experience gained in attempts to
 deploy RFC 1422 made it clear that the v1 and v2 certificate formats
 are deficient in several respects.  Most importantly, more fields
 were needed to carry information which PEM design and implementation
 experience has proven necessary.  In response to these new
 requirements, ISO/IEC/ITU and ANSI X9 developed the X.509 version 3
 (v3) certificate format.  The v3 format extends the v2 format by
 adding provision for additional extension fields.  Particular
 extension field types may be specified in standards or may be defined
 and registered by any organization or community. In June 1996,
 standardization of the basic v3 format was completed [X.509].
 ISO/IEC/ITU and ANSI X9 have also developed standard extensions for
 use in the v3 extensions field [X.509][X9.55].  These extensions can
 convey such data as additional subject identification information,
 key attribute information, policy information, and certification path
 constraints.

Housley, et. al. Standards Track [Page 9] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 However, the ISO/IEC/ITU and ANSI X9 standard extensions are very
 broad in their applicability.  In order to develop interoperable
 implementations of X.509 v3 systems for Internet use, it is necessary
 to specify a profile for use of the X.509 v3 extensions tailored for
 the Internet.  It is one goal of this document to specify a profile
 for Internet WWW, electronic mail, and IPsec applications.
 Environments with additional requirements may build on this profile
 or may replace it.

3.2 Certification Paths and Trust

 A user of a security service requiring knowledge of a public key
 generally needs to obtain and validate a certificate containing the
 required public key. If the public-key user does not already hold an
 assured copy of the public key of the CA that signed the certificate,
 the CA's name, and related information (such as the validity period
 or name constraints), then it might need an additional certificate to
 obtain that public key.  In general, a chain of multiple certificates
 may be needed, comprising a certificate of the public key owner (the
 end entity) signed by one CA, and zero or more additional
 certificates of CAs signed by other CAs.  Such chains, called
 certification paths, are required because a public key user is only
 initialized with a limited number of assured CA public keys.
 There are different ways in which CAs might be configured in order
 for public key users to be able to find certification paths.  For
 PEM, RFC 1422 defined a rigid hierarchical structure of CAs.  There
 are three types of PEM certification authority:
    (a)  Internet Policy Registration Authority (IPRA):  This
    authority, operated under the auspices of the Internet Society,
    acts as the root of the PEM certification hierarchy at level 1.
    It issues certificates only for the next level of authorities,
    PCAs.  All certification paths start with the IPRA.
    (b)  Policy Certification Authorities (PCAs):  PCAs are at level 2
    of the hierarchy, each PCA being certified by the IPRA.  A PCA
    shall establish and publish a statement of its policy with respect
    to certifying users or subordinate certification authorities.
    Distinct PCAs aim to satisfy different user needs. For example,
    one PCA (an organizational PCA) might support the general
    electronic mail needs of commercial organizations, and another PCA
    (a high-assurance PCA) might have a more stringent policy designed
    for satisfying legally binding digital signature requirements.

Housley, et. al. Standards Track [Page 10] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

    (c)  Certification Authorities (CAs):  CAs are at level 3 of the
    hierarchy and can also be at lower levels. Those at level 3 are
    certified by PCAs.  CAs represent, for example, particular
    organizations, particular organizational units (e.g., departments,
    groups, sections), or particular geographical areas.
 RFC 1422 furthermore has a name subordination rule which requires
 that a CA can only issue certificates for entities whose names are
 subordinate (in the X.500 naming tree) to the name of the CA itself.
 The trust associated with a PEM certification path is implied by the
 PCA name. The name subordination rule ensures that CAs below the PCA
 are sensibly constrained as to the set of subordinate entities they
 can certify (e.g., a CA for an organization can only certify entities
 in that organization's name tree). Certificate user systems are able
 to mechanically check that the name subordination rule has been
 followed.
 The RFC 1422 uses the X.509 v1 certificate formats. The limitations
 of X.509 v1 required imposition of several structural restrictions to
 clearly associate policy information or restrict the utility of
 certificates.  These restrictions included:
    (a) a pure top-down hierarchy, with all certification paths
    starting from IPRA;
    (b) a naming subordination rule restricting the names of a CA's
    subjects; and
    (c) use of the PCA concept, which requires knowledge of individual
    PCAs to be built into certificate chain verification logic.
    Knowledge of individual PCAs was required to determine if a chain
    could be accepted.
 With X.509 v3, most of the requirements addressed by RFC 1422 can be
 addressed using certificate extensions, without a need to restrict
 the CA structures used.  In particular, the certificate extensions
 relating to certificate policies obviate the need for PCAs and the
 constraint extensions obviate the need for the name subordination
 rule.  As a result, this document supports a more flexible
 architecture, including:
    (a) Certification paths may start with a public key of a CA in a
    user's own domain, or with the public key of the top of a
    hierarchy.  Starting with the public key of a CA in a user's own
    domain has certain advantages.  In some environments, the local
    domain is the most trusted.

Housley, et. al. Standards Track [Page 11] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

    (b)  Name constraints may be imposed through explicit inclusion of
    a name constraints extension in a certificate, but are not
    required.
    (c)  Policy extensions and policy mappings replace the PCA
    concept, which permits a greater degree of automation.  The
    application can determine if the certification path is acceptable
    based on the contents of the certificates instead of a priori
    knowledge of PCAs. This permits automation of certificate chain
    processing.

3.3 Revocation

 When a certificate is issued, it is expected to be in use for its
 entire validity period.  However, various circumstances may cause a
 certificate to become invalid prior to the expiration of the validity
 period. Such circumstances include change of name, change of
 association between subject and CA (e.g., an employee terminates
 employment with an organization), and compromise or suspected
 compromise of the corresponding private key.  Under such
 circumstances, the CA needs to revoke the certificate.
 X.509 defines one method of certificate revocation.  This method
 involves each CA periodically issuing a signed data structure called
 a certificate revocation list (CRL).  A CRL is a time stamped list
 identifying revoked certificates which is signed by a CA and made
 freely available in a public repository.  Each revoked certificate is
 identified in a CRL by its certificate serial number. When a
 certificate-using system uses a certificate (e.g., for verifying a
 remote user's digital signature), that system not only checks the
 certificate signature and validity but also acquires a suitably-
 recent CRL and checks that the certificate serial number is not on
 that CRL.  The meaning of "suitably-recent" may vary with local
 policy, but it usually means the most recently-issued CRL.  A CA
 issues a new CRL on a regular periodic basis (e.g., hourly, daily, or
 weekly).  An entry is added to the CRL as part of the next update
 following notification of revocation. An entry may be removed from
 the CRL after appearing on one regularly scheduled CRL issued beyond
 the revoked certificate's validity period.
 An advantage of this revocation method is that CRLs may be
 distributed by exactly the same means as certificates themselves,
 namely, via untrusted communications and server systems.
 One limitation of the CRL revocation method, using untrusted
 communications and servers, is that the time granularity of
 revocation is limited to the CRL issue period.  For example, if a
 revocation is reported now, that revocation will not be reliably

Housley, et. al. Standards Track [Page 12] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 notified to certificate-using systems until the next periodic CRL is
 issued -- this may be up to one hour, one day, or one week depending
 on the frequency that the CA issues CRLs.
 As with the X.509 v3 certificate format, in order to facilitate
 interoperable implementations from multiple vendors, the X.509 v2 CRL
 format needs to be profiled for Internet use.  It is one goal of this
 document to specify that profile.  However, this profile does not
 require CAs to issue CRLs. Message formats and protocols supporting
 on-line revocation notification may be defined in other PKIX
 specifications.  On-line methods of revocation notification may be
 applicable in some environments as an alternative to the X.509 CRL.
 On-line revocation checking may significantly reduce the latency
 between a revocation report and the distribution of the information
 to relying parties.  Once the CA accepts the report as authentic and
 valid, any query to the on-line service will correctly reflect the
 certificate validation impacts of the revocation.  However, these
 methods impose new security requirements; the certificate validator
 shall trust the on-line validation service while the repository does
 not need to be trusted.

3.4 Operational Protocols

 Operational protocols are required to deliver certificates and CRLs
 (or status information) to certificate using client systems.
 Provision is needed for a variety of different means of certificate
 and CRL delivery, including distribution procedures based on LDAP,
 HTTP, FTP, and X.500.  Operational protocols supporting these
 functions are defined in other PKIX specifications.  These
 specifications may include definitions of message formats and
 procedures for supporting all of the above operational environments,
 including definitions of or references to appropriate MIME content
 types.

3.5 Management Protocols

 Management protocols are required to support on-line interactions
 between PKI user and management entities.  For example, a management
 protocol might be used between a CA and a client system with which a
 key pair is associated, or between two CAs which cross-certify each
 other.  The set of functions which potentially need to be supported
 by management protocols include:
    (a)  registration:  This is the process whereby a user first makes
    itself known to a CA (directly, or through an RA), prior to that
    CA issuing  a certificate or certificates for that user.

Housley, et. al. Standards Track [Page 13] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

    (b)  initialization:  Before a client system can operate securely
    it is necessary to install key materials which have the
    appropriate relationship with keys stored elsewhere in the
    infrastructure.  For example, the client needs to be securely
    initialized with the public key and other assured information of
    the trusted CA(s), to be used in validating certificate paths.
    Furthermore, a client typically needs to be initialized with its
    own key pair(s).
    (c)  certification:  This  is the process in which a CA issues a
    certificate for a user's public key, and returns that certificate
    to the user's client system and/or posts that certificate in a
    repository.
    (d)  key pair recovery:  As an option, user client key materials
    (e.g., a user's private key used for encryption purposes) may be
    backed up by a CA or a key backup system.  If a user needs to
    recover these backed up key materials (e.g., as a result of a
    forgotten password or a lost key chain file), an on-line protocol
    exchange may be needed to support such recovery.
    (e)  key pair update:  All key pairs need to be updated regularly,
    i.e., replaced with a new key pair, and new certificates issued.
    (f)  revocation request:  An authorized person advises a CA of an
    abnormal situation requiring certificate revocation.
    (g)  cross-certification:  Two CAs exchange information used in
    establishing a cross-certificate. A cross-certificate is a
    certificate issued by one CA to another CA which contains a CA
    signature key used for issuing certificates.
 Note that on-line protocols are not the only way of implementing the
 above functions.  For all functions there are off-line methods of
 achieving the same result, and this specification does not mandate
 use of on-line protocols.  For example, when hardware tokens are
 used, many of the functions may be achieved as part of the physical
 token delivery.  Furthermore, some of the above functions may be
 combined into one protocol exchange.  In particular, two or more of
 the registration, initialization, and certification functions can be
 combined into one protocol exchange.
 The PKIX series of specifications may define a set of standard
 message formats supporting the above functions in future
 specifications.  In that case, the protocols for conveying these
 messages in different environments (e.g., on-line, file transfer, e-
 mail, and WWW) will also be described in those specifications.

Housley, et. al. Standards Track [Page 14] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

4 Certificate and Certificate Extensions Profile

 This section presents a profile for public key certificates that will
 foster interoperability and a reusable PKI.  This section is based
 upon the X.509 v3 certificate format and the standard certificate
 extensions defined in [X.509].  The ISO/IEC/ITU documents use the
 1993 version of ASN.1; while this document uses the 1988 ASN.1
 syntax, the encoded certificate and standard extensions are
 equivalent.  This section also defines private extensions required to
 support a PKI for the Internet community.
 Certificates may be used in a wide range of applications and
 environments covering a broad spectrum of interoperability goals and
 a broader spectrum of operational and assurance requirements.  The
 goal of this document is to establish a common baseline for generic
 applications requiring broad interoperability and limited special
 purpose requirements.  In particular, the emphasis will be on
 supporting the use of X.509 v3 certificates for informal Internet
 electronic mail, IPsec, and WWW applications.

4.1 Basic Certificate Fields

 The X.509 v3 certificate basic syntax is as follows.  For signature
 calculation, the certificate is encoded using the ASN.1 distinguished
 encoding rules (DER) [X.208].  ASN.1 DER encoding is a tag, length,
 value encoding system for each element.
 Certificate  ::=  SEQUENCE  {
      tbsCertificate       TBSCertificate,
      signatureAlgorithm   AlgorithmIdentifier,
      signatureValue       BIT STRING  }
 TBSCertificate  ::=  SEQUENCE  {
      version         [0]  EXPLICIT Version DEFAULT v1,
      serialNumber         CertificateSerialNumber,
      signature            AlgorithmIdentifier,
      issuer               Name,
      validity             Validity,
      subject              Name,
      subjectPublicKeyInfo SubjectPublicKeyInfo,
      issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
                           -- If present, version shall be v2 or v3
      subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
                           -- If present, version shall be v2 or v3
      extensions      [3]  EXPLICIT Extensions OPTIONAL
                           -- If present, version shall be v3
      }

Housley, et. al. Standards Track [Page 15] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }
 CertificateSerialNumber  ::=  INTEGER
 Validity ::= SEQUENCE {
      notBefore      Time,
      notAfter       Time }
 Time ::= CHOICE {
      utcTime        UTCTime,
      generalTime    GeneralizedTime }
 UniqueIdentifier  ::=  BIT STRING
 SubjectPublicKeyInfo  ::=  SEQUENCE  {
      algorithm            AlgorithmIdentifier,
      subjectPublicKey     BIT STRING  }
 Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension
 Extension  ::=  SEQUENCE  {
      extnID      OBJECT IDENTIFIER,
      critical    BOOLEAN DEFAULT FALSE,
      extnValue   OCTET STRING  }
 The following items describe the X.509 v3 certificate for use in the
 Internet.

4.1.1 Certificate Fields

 The Certificate is a SEQUENCE of three required fields. The fields
 are described in detail in the following subsections.

4.1.1.1 tbsCertificate

 The field contains the names of the subject and issuer, a public key
 associated with the subject, a validity period, and other associated
 information.  The fields are described in detail in section 4.1.2;
 the tbscertificate may also include extensions which are described in
 section 4.2.

4.1.1.2 signatureAlgorithm

 The signatureAlgorithm field contains the identifier for the
 cryptographic algorithm used by the CA to sign this certificate.
 Section 7.2 lists the supported signature algorithms.
 An algorithm identifier is defined by the following ASN.1 structure:

Housley, et. al. Standards Track [Page 16] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 AlgorithmIdentifier  ::=  SEQUENCE  {
      algorithm               OBJECT IDENTIFIER,
      parameters              ANY DEFINED BY algorithm OPTIONAL  }
 The algorithm identifier is used to identify a cryptographic
 algorithm.  The OBJECT IDENTIFIER component identifies the algorithm
 (such as DSA with SHA-1).  The contents of the optional parameters
 field will vary according to the algorithm identified. Section 7.2
 lists the supported algorithms for this specification.
 This field MUST contain the same algorithm identifier as the
 signature field in the sequence tbsCertificate (see sec. 4.1.2.3).

4.1.1.3 signatureValue

 The signatureValue field contains a digital signature computed upon
 the ASN.1 DER encoded tbsCertificate.  The ASN.1 DER encoded
 tbsCertificate is used as the input to the signature function. This
 signature value is then ASN.1 encoded as a BIT STRING and included in
 the Certificate's signature field. The details of this process are
 specified for each of the supported algorithms in Section 7.2.
 By generating this signature, a CA certifies the validity of the
 information in the tbsCertificate field.  In particular, the CA
 certifies the binding between the public key material and the subject
 of the certificate.

4.1.2 TBSCertificate

 The sequence TBSCertificate contains information associated with the
 subject of the certificate and the CA who issued it.  Every
 TBSCertificate contains the names of the subject and issuer, a public
 key associated with the subject, a validity period, a version number,
 and a serial number; some may contain optional unique identifier
 fields.  The remainder of this section describes the syntax and
 semantics of these fields.  A TBSCertificate may also include
 extensions.  Extensions for the Internet PKI are described in Section
 4.2.

4.1.2.1 Version

 This field describes the version of the encoded certificate.  When
 extensions are used, as expected in this profile, use X.509 version 3
 (value is 2).  If no extensions are present, but a UniqueIdentifier
 is present, use version 2 (value is 1).  If only basic fields are
 present, use version 1 (the value is omitted from the certificate as
 the default value).

Housley, et. al. Standards Track [Page 17] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 Implementations SHOULD be prepared to accept any version certificate.
 At a minimum, conforming implementations MUST recognize version 3
 certificates.
 Generation of version 2 certificates is not expected by
 implementations based on this profile.

4.1.2.2 Serial number

 The serial number is an integer assigned by the CA to each
 certificate.  It MUST be unique for each certificate issued by a
 given CA (i.e., the issuer name and serial number identify a unique
 certificate).

4.1.2.3 Signature

 This field contains the algorithm identifier for the algorithm used
 by the CA to sign the certificate.
 This field MUST contain the same algorithm identifier as the
 signatureAlgorithm field in the sequence Certificate (see sec.
 4.1.1.2).  The contents of the optional parameters field will vary
 according to the algorithm identified.  Section 7.2 lists the
 supported signature algorithms.

4.1.2.4 Issuer

 The issuer field identifies the entity who has signed and issued the
 certificate.  The issuer field MUST contain a non-empty distinguished
 name (DN).  The issuer field is defined as the X.501 type Name.
 [X.501] Name is defined by the following ASN.1 structures:
 Name ::= CHOICE {
   RDNSequence }
 RDNSequence ::= SEQUENCE OF RelativeDistinguishedName
 RelativeDistinguishedName ::=
   SET OF AttributeTypeAndValue
 AttributeTypeAndValue ::= SEQUENCE {
   type     AttributeType,
   value    AttributeValue }
 AttributeType ::= OBJECT IDENTIFIER
 AttributeValue ::= ANY DEFINED BY AttributeType

Housley, et. al. Standards Track [Page 18] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 DirectoryString ::= CHOICE {
       teletexString           TeletexString (SIZE (1..MAX)),
       printableString         PrintableString (SIZE (1..MAX)),
       universalString         UniversalString (SIZE (1..MAX)),
       utf8String              UTF8String (SIZE (1.. MAX)),
       bmpString               BMPString (SIZE (1..MAX)) }
 The Name describes a hierarchical name composed of attributes, such
 as country name, and corresponding values, such as US.  The type of
 the component AttributeValue is determined by the AttributeType; in
 general it will be a DirectoryString.
 The DirectoryString type is defined as a choice of PrintableString,
 TeletexString, BMPString, UTF8String, and UniversalString.  The
 UTF8String encoding is the preferred encoding, and all certificates
 issued after December 31, 2003 MUST use the UTF8String encoding of
 DirectoryString (except as noted below).  Until that date, conforming
 CAs MUST choose from the following options when creating a
 distinguished name, including their own:
    (a) if the character set is sufficient, the string MAY be
    represented as a PrintableString;
    (b) failing (a), if the BMPString character set is sufficient the
    string MAY be represented as a BMPString; and
    (c) failing (a) and (b), the string MUST be represented as a
    UTF8String.  If (a) or (b) is satisfied, the CA MAY still choose
    to represent the string as a UTF8String.
 Exceptions to the December 31, 2003 UTF8 encoding requirements are as
 follows:
    (a) CAs MAY issue "name rollover" certificates to support an
    orderly migration to UTF8String encoding.  Such certificates would
    include the CA's UTF8String encoded name as issuer and and the old
    name encoding as subject, or vice-versa.
    (b) As stated in section 4.1.2.6, the subject field MUST be
    populated with a non-empty distinguished name matching the
    contents of the issuer field in all certificates issued by the
    subject CA regardless of encoding.
 The TeletexString and UniversalString are included for backward
 compatibility, and should not be used for certificates for new
 subjects.  However, these types may be used in certificates where the
 name was previously established.  Certificate users SHOULD be
 prepared to receive certificates with these types.

Housley, et. al. Standards Track [Page 19] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 In addition, many legacy implementations support names encoded in the
 ISO 8859-1 character set (Latin1String) but tag them as
 TeletexString.  The Latin1String includes characters used in Western
 European countries which are not part of the TeletexString charcter
 set.  Implementations that process TeletexString SHOULD be prepared
 to handle the entire ISO 8859-1 character set.[ISO 8859-1]
 As noted above, distinguished names are composed of attributes.  This
 specification does not restrict the set of attribute types that may
 appear in names.  However, conforming implementations MUST be
 prepared to receive certificates with issuer names containing the set
 of attribute types defined below.  This specification also recommends
 support for additional attribute types.
 Standard sets of attributes have been defined in the X.500 series of
 specifications.[X.520]  Implementations of this specification MUST be
 prepared to receive the following standard attribute types in issuer
 names: country, organization, organizational-unit, distinguished name
 qualifier, state or province name,  and common name (e.g., "Susan
 Housley").  In addition, implementations of this specification SHOULD
 be prepared to receive the following standard attribute types in
 issuer names: locality, title,  surname, given name, initials, and
 generation qualifier (e.g., "Jr.", "3rd", or "IV").  The syntax and
 associated object identifiers (OIDs) for these attribute types are
 provided in the ASN.1 modules in Appendices A and B.
 In addition, implementations of this specification MUST be prepared
 to receive the domainComponent attribute, as defined in [RFC 2247].
 The Domain (Nameserver) System (DNS) provides a hierarchical resource
 labeling system.  This attribute provides is a convenient mechanism
 for organizations that wish to use DNs that parallel their DNS names.
 This is not a replacement for the dNSName component of the
 alternative name field. Implementations are not required to convert
 such names into DNS names. The syntax and associated OID for this
 attribute type is provided in the ASN.1 modules in Appendices A and
 B.
 Certificate users MUST be prepared to process the issuer
 distinguished name and subject distinguished name (see sec. 4.1.2.6)
 fields to perform name chaining for certification path validation
 (see section 6). Name chaining is performed by matching the issuer
 distinguished name in one certificate with the subject name in a CA
 certificate.
 This specification requires only a subset of the name comparison
 functionality specified in the X.500 series of specifications.  The
 requirements for conforming implementations are as follows:

Housley, et. al. Standards Track [Page 20] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

    (a) attribute values encoded in different types (e.g.,
    PrintableString and BMPString) may be assumed to represent
    different strings;
    (b) attribute values in types other than PrintableString are case
    sensitive (this permits matching of attribute values as binary
    objects);
    (c) attribute values in PrintableString are not case sensitive
    (e.g., "Marianne Swanson" is the same as "MARIANNE SWANSON"); and
    (d) attribute values in PrintableString are compared after
    removing leading and trailing white space and converting internal
    substrings of one or more consecutive white space characters to a
    single space.
 These name comparison rules permit a certificate user to validate
 certificates issued using languages or encodings unfamiliar to the
 certificate user.
 In addition, implementations of this specification MAY use these
 comparison rules to process unfamiliar attribute types for name
 chaining. This allows implementations to process certificates with
 unfamiliar attributes in the issuer name.
 Note that the comparison rules defined in the X.500 series of
 specifications indicate that the character sets used to encode data
 in distinguished names are irrelevant.  The characters themselves are
 compared without regard to encoding. Implementations of the profile
 are permitted to use the comparison algorithm defined in the X.500
 series.  Such an implementation will recognize a superset of name
 matches recognized by the algorithm specified above.

4.1.2.5 Validity

 The certificate validity period is the time interval during which the
 CA warrants that it will maintain information about the status of the
 certificate. The field is represented as a SEQUENCE of two dates:
 the date on which the certificate validity period begins (notBefore)
 and the date on which the certificate validity period ends
 (notAfter).  Both notBefore and notAfter may be encoded as UTCTime or
 GeneralizedTime.
 CAs conforming to this profile MUST always encode certificate
 validity dates through the year 2049 as UTCTime; certificate validity
 dates in 2050 or later MUST be encoded as GeneralizedTime.

Housley, et. al. Standards Track [Page 21] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

4.1.2.5.1 UTCTime

 The universal time type, UTCTime, is a standard ASN.1 type intended
 for international applications where local time alone is not
 adequate.  UTCTime specifies the year through the two low order
 digits and time is specified to the precision of one minute or one
 second.  UTCTime includes either Z (for Zulu, or Greenwich Mean Time)
 or a time differential.
 For the purposes of this profile, UTCTime values MUST be expressed
 Greenwich Mean Time (Zulu) and MUST include seconds (i.e., times are
 YYMMDDHHMMSSZ), even where the number of seconds is zero.  Conforming
 systems MUST interpret the year field (YY) as follows:
    Where YY is greater than or equal to 50, the year shall be
    interpreted as 19YY; and
    Where YY is less than 50, the year shall be interpreted as 20YY.

4.1.2.5.2 GeneralizedTime

 The generalized time type, GeneralizedTime, is a standard ASN.1 type
 for variable precision representation of time.  Optionally, the
 GeneralizedTime field can include a representation of the time
 differential between local and Greenwich Mean Time.
 For the purposes of this profile, GeneralizedTime values MUST be
 expressed Greenwich Mean Time (Zulu) and MUST include seconds (i.e.,
 times are YYYYMMDDHHMMSSZ), even where the number of seconds is zero.
 GeneralizedTime values MUST NOT include fractional seconds.

4.1.2.6 Subject

 The subject field identifies the entity associated with the public
 key stored in the subject public key field.  The subject name may be
 carried in the subject field and/or the subjectAltName extension.  If
 the subject is a CA (e.g., the basic constraints extension, as
 discussed in 4.2.1.10, is present and the value of cA is TRUE,) then
 the subject field MUST be populated with a non-empty distinguished
 name matching the contents of the issuer field (see sec. 4.1.2.4) in
 all certificates issued by the subject CA.  If subject naming
 information is present only in the subjectAltName extension (e.g., a
 key bound only to an email address or URI), then the subject name
 MUST be an empty sequence and the subjectAltName extension MUST be
 critical.

Housley, et. al. Standards Track [Page 22] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 Where it is non-empty, the subject field MUST contain an X.500
 distinguished name (DN). The DN MUST be unique for each subject
 entity certified by the one CA as defined by the issuer name field. A
 CA may issue more than one certificate with the same DN to the same
 subject entity.
 The subject name field is defined as the X.501 type Name.
 Implementation requirements for this field are those defined for the
 issuer field (see sec.  4.1.2.4).  When encoding attribute values of
 type DirectoryString, the encoding rules for the issuer field MUST be
 implemented.  Implementations of this specification MUST be prepared
 to receive subject names containing the attribute types required for
 the issuer field.  Implementations of this specification SHOULD be
 prepared to receive subject names containing the recommended
 attribute types for the issuer field.  The syntax and associated
 object identifiers (OIDs) for these attribute types are provided in
 the ASN.1 modules in Appendices A and B.  Implementations of this
 specification MAY use these comparison rules to process unfamiliar
 attribute types (i.e., for name chaining). This allows
 implementations to process certificates with unfamiliar attributes in
 the subject name.
 In addition, legacy implementations exist where an RFC 822 name is
 embedded in the subject distinguished name as an EmailAddress
 attribute.  The attribute value for EmailAddress is of type IA5String
 to permit inclusion of the character '@', which is not part of the
 PrintableString character set.  EmailAddress attribute values are not
 case sensitive (e.g., "fanfeedback@redsox.com" is the same as
 "FANFEEDBACK@REDSOX.COM").
 Conforming implementations generating new certificates with
 electronic mail addresses MUST use the rfc822Name in the subject
 alternative name field (see sec. 4.2.1.7) to describe such
 identities.  Simultaneous inclusion of the EmailAddress attribute in
 the subject distinguished name to support legacy implementations is
 deprecated but permitted.

4.1.2.7 Subject Public Key Info

 This field is used to carry the public key and identify the algorithm
 with which the key is used. The algorithm is identified using the
 AlgorithmIdentifier structure specified in section 4.1.1.2. The
 object identifiers for the supported algorithms and the methods for
 encoding the public key materials (public key and parameters) are
 specified in section 7.3.

Housley, et. al. Standards Track [Page 23] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

4.1.2.8 Unique Identifiers

 These fields may only appear if the version is 2 or 3 (see sec.
 4.1.2.1).  The subject and issuer unique identifiers are present in
 the certificate to handle the possibility of reuse of subject and/or
 issuer names over time.  This profile recommends that names not be
 reused for different entities and that Internet certificates not make
 use of unique identifiers.  CAs conforming to this profile SHOULD NOT
 generate certificates with unique identifiers.  Applications
 conforming to this profile SHOULD be capable of parsing unique
 identifiers and making comparisons.

4.1.2.9 Extensions

 This field may only appear if the version is 3 (see sec. 4.1.2.1).
 If present, this field is a SEQUENCE of one or more certificate
 extensions. The format and content of certificate extensions in the
 Internet PKI is defined in section 4.2.

4.2 Standard Certificate Extensions

 The extensions defined for X.509 v3 certificates provide methods for
 associating additional attributes with users or public keys and for
 managing the certification hierarchy.  The X.509 v3 certificate
 format also allows communities to define private extensions to carry
 information unique to those communities.  Each extension in a
 certificate may be designated as critical or non-critical.  A
 certificate using system MUST reject the certificate if it encounters
 a critical extension it does not recognize; however, a non-critical
 extension may be ignored if it is not recognized.  The following
 sections present recommended extensions used within Internet
 certificates and standard locations for information.  Communities may
 elect to use additional extensions; however, caution should be
 exercised in adopting any critical extensions in certificates which
 might prevent use in a general context.
 Each extension includes an OID and an ASN.1 structure.  When an
 extension appears in a certificate, the OID appears as the field
 extnID and the corresponding ASN.1 encoded structure is the value of
 the octet string extnValue.  Only one instance of a particular
 extension may appear in a particular certificate. For example, a
 certificate may contain only one authority key identifier extension
 (see sec. 4.2.1.1).  An extension includes the boolean critical, with
 a default value of FALSE.  The text for each extension specifies the
 acceptable values for the critical field.

Housley, et. al. Standards Track [Page 24] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 Conforming CAs MUST support key identifiers (see sec. 4.2.1.1 and
 4.2.1.2), basic constraints (see sec. 4.2.1.10), key usage (see sec.
 4.2.1.3), and certificate policies (see sec. 4.2.1.5) extensions. If
 the CA issues certificates with an empty sequence for the subject
 field, the CA MUST support the subject alternative name extension
 (see sec. 4.2.1.7).  Support for the remaining extensions is
 OPTIONAL. Conforming CAs may support extensions that are not
 identified within this specification; certificate issuers are
 cautioned that marking such extensions as critical may inhibit
 interoperability.
 At a minimum, applications conforming to this profile MUST recognize
 the extensions which must or may be critical in this specification.
 These extensions are:  key usage (see sec. 4.2.1.3), certificate
 policies (see sec. 4.2.1.5), the subject alternative name (see sec.
 4.2.1.7), basic constraints (see sec. 4.2.1.10), name constraints
 (see sec. 4.2.1.11), policy constraints (see sec. 4.2.1.12), and
 extended key usage (see sec. 4.2.1.13).
 In addition, this profile RECOMMENDS application support for the
 authority and subject key identifier (see sec. 4.2.1.1 and 4.2.1.2)
 extensions.

4.2.1 Standard Extensions

 This section identifies standard certificate extensions defined in
 [X.509] for use in the Internet PKI.  Each extension is associated
 with an OID defined in [X.509].  These OIDs are members of the id-ce
 arc, which is defined by the following:
 id-ce   OBJECT IDENTIFIER ::=  {joint-iso-ccitt(2) ds(5) 29}

4.2.1.1 Authority Key Identifier

 The authority key identifier extension provides a means of
 identifying the public key corresponding to the private key used to
 sign a certificate. This extension is used where an issuer has
 multiple signing keys (either due to multiple concurrent key pairs or
 due to changeover).  The identification may be based on either the
 key identifier (the subject key identifier in the issuer's
 certificate) or on the issuer name and serial number.
 The keyIdentifier field of the authorityKeyIdentifier extension MUST
 be included in all certificates generated by conforming CAs to
 facilitate chain building.  There is one exception; where a CA
 distributes its public key in the form of a "self-signed"
 certificate, the authority key identifier may be omitted.  In this
 case, the subject and authority key identifiers would be identical.

Housley, et. al. Standards Track [Page 25] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 The value of the keyIdentifier field SHOULD be derived from the
 public key used to verify the certificate's signature or a method
 that generates unique values.  Two common methods for generating key
 identifiers from the public key are described in (sec. 4.2.1.2). One
 common method for generating unique values isdescribed in (sec.
 4.2.1.2).  Where a key identifier has not been previously
 established, this specification recommends use of one of these
 methods for generating keyIdentifiers.
 This profile recommends support for the key identifier method by all
 certificate users.
 This extension MUST NOT be marked critical.
 id-ce-authorityKeyIdentifier OBJECT IDENTIFIER ::=  { id-ce 35 }
 AuthorityKeyIdentifier ::= SEQUENCE {
    keyIdentifier             [0] KeyIdentifier           OPTIONAL,
    authorityCertIssuer       [1] GeneralNames            OPTIONAL,
    authorityCertSerialNumber [2] CertificateSerialNumber OPTIONAL  }
 KeyIdentifier ::= OCTET STRING

4.2.1.2 Subject Key Identifier

 The subject key identifier extension provides a means of identifying
 certificates that contain a particular public key.
 To facilitate chain building, this extension MUST appear in all con-
 forming CA certificates, that is, all certificates including the
 basic constraints extension (see sec. 4.2.1.10) where the value of cA
 is TRUE.  The value of the subject key identifier MUST be the value
 placed in the key identifier field of the Authority Key Identifier
 extension (see sec. 4.2.1.1) of certificates issued by the subject of
 this certificate.
 For CA certificates, subject key identifiers SHOULD be derived from
 the public key or a method that generates unique values.  Two common
 methods for generating key identifiers from the public key are:
    (1) The keyIdentifier is composed of the 160-bit SHA-1 hash of the
    value of the BIT STRING subjectPublicKey (excluding the tag,
    length, and number of unused bits).
    (2) The keyIdentifier is composed of a four bit type field with
    the value 0100 followed by the least significant 60 bits of the
    SHA-1 hash of the value of the BIT STRING subjectPublicKey.

Housley, et. al. Standards Track [Page 26] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 One common method for generating unique values is a monotomically
 increasing sequence of integers.
 For end entity certificates, the subject key identifier extension
 provides a means for identifying certificates containing the
 particular public key used in an application. Where an end entity has
 obtained multiple certificates, especially from multiple CAs, the
 subject key identifier provides a means to quickly identify the set
 of certificates containing a particular public key. To assist
 applications in identificiation the appropriate end entity
 certificate, this extension SHOULD be included in all end entity
 certificates.
 For end entity certificates, subject key identifiers SHOULD be
 derived from the public key.  Two common methods for generating key
 identifiers from the public key are identifed above.
 Where a key identifier has not been previously established, this
 specification recommends use of one of these methods for generating
 keyIdentifiers.
 This extension MUST NOT be marked critical.
 id-ce-subjectKeyIdentifier OBJECT IDENTIFIER ::=  { id-ce 14 }
 SubjectKeyIdentifier ::= KeyIdentifier

4.2.1.3 Key Usage

 The key usage extension defines the purpose (e.g., encipherment,
 signature, certificate signing) of the key contained in the
 certificate.  The usage restriction might be employed when a key that
 could be used for more than one operation is to be restricted.  For
 example, when an RSA key should be used only for signing, the
 digitalSignature and/or nonRepudiation bits would be asserted.
 Likewise, when an RSA key should be used only for key management, the
 keyEncipherment bit would be asserted. When used, this extension
 SHOULD be marked critical.
    id-ce-keyUsage OBJECT IDENTIFIER ::=  { id-ce 15 }
    KeyUsage ::= BIT STRING {
         digitalSignature        (0),
         nonRepudiation          (1),
         keyEncipherment         (2),
         dataEncipherment        (3),
         keyAgreement            (4),
         keyCertSign             (5),

Housley, et. al. Standards Track [Page 27] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

         cRLSign                 (6),
         encipherOnly            (7),
         decipherOnly            (8) }
 Bits in the KeyUsage type are used as follows:
    The digitalSignature bit is asserted when the subject public key
    is used with a digital signature mechanism to support security
    services other than non-repudiation (bit 1), certificate signing
    (bit 5), or revocation information signing (bit 6). Digital
    signature mechanisms are often used for entity authentication and
    data origin authentication with integrity.
    The nonRepudiation bit is asserted when the subject public key is
    used to verify digital signatures used to provide a non-
    repudiation service which protects against the signing entity
    falsely denying some action, excluding certificate or CRL signing.
    The keyEncipherment bit is asserted when the subject public key is
    used for key transport.  For example, when an RSA key is to be
    used for key management, then this bit shall asserted.
    The dataEncipherment bit is asserted when the subject public key
    is used for enciphering user data, other than cryptographic keys.
    The keyAgreement bit is asserted when the subject public key is
    used for key agreement.  For example, when a Diffie-Hellman key is
    to be used for key management, then this bit shall asserted.
    The keyCertSign bit is asserted when the subject public key is
    used for verifying a signature on certificates.  This bit may only
    be asserted in CA certificates.
    The cRLSign bit is asserted when the subject public key is used
    for verifying a signature on revocation information (e.g., a CRL).
    The meaning of the encipherOnly bit is undefined in the absence of
    the keyAgreement bit.  When the encipherOnly bit is asserted and
    the keyAgreement bit is also set, the subject public key may be
    used only for enciphering data while performing key agreement.
    The meaning of the decipherOnly bit is undefined in the absence of
    the keyAgreement bit.  When the decipherOnly bit is asserted and
    the keyAgreement bit is also set, the subject public key may be
    used only for deciphering data while performing key agreement.

Housley, et. al. Standards Track [Page 28] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 This profile does not restrict the combinations of bits that may be
 set in an instantiation of the keyUsage extension.  However,
 appropriate values for keyUsage extensions for particular algorithms
 are specified in section 7.3.

4.2.1.4 Private Key Usage Period

 This profile recommends against the use of this extension.  CAs
 conforming to this profile MUST NOT generate certificates with
 critical private key usage period extensions.
 The private key usage period extension allows the certificate issuer
 to specify a different validity period for the private key than the
 certificate. This extension is intended for use with digital
 signature keys.  This extension consists of two optional components,
 notBefore and notAfter.  The private key associated with the
 certificate should not be used to sign objects before or after the
 times specified by the two components, respectively. CAs conforming
 to this profile MUST NOT generate certificates with private key usage
 period extensions unless at least one of the two components is
 present.
 Where used, notBefore and notAfter are represented as GeneralizedTime
 and MUST be specified and interpreted as defined in section
 4.1.2.5.2.
 id-ce-privateKeyUsagePeriod OBJECT IDENTIFIER ::=  { id-ce 16 }
 PrivateKeyUsagePeriod ::= SEQUENCE {
      notBefore       [0]     GeneralizedTime OPTIONAL,
      notAfter        [1]     GeneralizedTime OPTIONAL }

4.2.1.5 Certificate Policies

 The certificate policies extension contains a sequence of one or more
 policy information terms, each of which consists of an object
 identifier (OID) and optional qualifiers.  These policy information
 terms indicate the policy under which the certificate has been issued
 and the purposes for which the certificate may be used.  Optional
 qualifiers, which may be present, are not expected to change the
 definition of the policy.
 Applications with specific policy requirements are expected to have a
 list of those policies which they will accept and to compare the
 policy OIDs in the certificate to that list.  If this extension is
 critical, the path validation software MUST be able to interpret this
 extension (including the optional qualifier), or MUST reject the
 certificate.

Housley, et. al. Standards Track [Page 29] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 To promote interoperability, this profile RECOMMENDS that policy
 information terms consist of only an OID.  Where an OID alone is
 insufficient, this profile strongly recommends that use of qualifiers
 be limited to those identified in this section.
 This specification defines two policy qualifier types for use by
 certificate policy writers and certificate issuers. The qualifier
 types are the CPS Pointer and User Notice qualifiers.
 The CPS Pointer qualifier contains a pointer to a Certification
 Practice Statement (CPS) published by the CA.  The pointer is in the
 form of a URI.
 User notice is intended for display to a relying party when a
 certificate is used.  The application software SHOULD display all
 user notices in all certificates of the certification path used,
 except that if a notice is duplicated only one copy need be
 displayed.  To prevent such duplication, this qualifier SHOULD only
 be present in end-entity certificates and CA certificates issued to
 other organizations.
 The user notice has two optional fields: the noticeRef field and the
 explicitText field.
    The noticeRef field, if used, names an organization and
    identifies, by number, a particular textual statement prepared by
    that organization.  For example, it might identify the
    organization "CertsRUs" and notice number 1.  In a typical
    implementation, the application software will have a notice file
    containing the current set of notices for CertsRUs; the
    application will extract the notice text from the file and display
    it.  Messages may be multilingual, allowing the software to select
    the particular language message for its own environment.
    An explicitText field includes the textual statement directly in
    the certificate.  The explicitText field is a string with a
    maximum size of 200 characters.
 If both the noticeRef and explicitText options are included in the
 one qualifier and if the application software can locate the notice
 text indicated by the noticeRef option then that text should be
 displayed; otherwise, the explicitText string should be displayed.
 id-ce-certificatePolicies OBJECT IDENTIFIER ::=  { id-ce 32 }
 certificatePolicies ::= SEQUENCE SIZE (1..MAX) OF PolicyInformation

Housley, et. al. Standards Track [Page 30] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 PolicyInformation ::= SEQUENCE {
      policyIdentifier   CertPolicyId,
      policyQualifiers   SEQUENCE SIZE (1..MAX) OF
                              PolicyQualifierInfo OPTIONAL }
 CertPolicyId ::= OBJECT IDENTIFIER
 PolicyQualifierInfo ::= SEQUENCE {
      policyQualifierId  PolicyQualifierId,
      qualifier          ANY DEFINED BY policyQualifierId }
  1. - policyQualifierIds for Internet policy qualifiers
 id-qt          OBJECT IDENTIFIER ::=  { id-pkix 2 }
 id-qt-cps      OBJECT IDENTIFIER ::=  { id-qt 1 }
 id-qt-unotice  OBJECT IDENTIFIER ::=  { id-qt 2 }
 PolicyQualifierId ::=
      OBJECT IDENTIFIER ( id-qt-cps | id-qt-unotice )
 Qualifier ::= CHOICE {
      cPSuri           CPSuri,
      userNotice       UserNotice }
 CPSuri ::= IA5String
 UserNotice ::= SEQUENCE {
      noticeRef        NoticeReference OPTIONAL,
      explicitText     DisplayText OPTIONAL}
 NoticeReference ::= SEQUENCE {
      organization     DisplayText,
      noticeNumbers    SEQUENCE OF INTEGER }
 DisplayText ::= CHOICE {
      visibleString    VisibleString  (SIZE (1..200)),
      bmpString        BMPString      (SIZE (1..200)),
      utf8String       UTF8String     (SIZE (1..200)) }

4.2.1.6 Policy Mappings

 This extension is used in CA certificates.  It lists one or more
 pairs of OIDs; each pair includes an issuerDomainPolicy and a
 subjectDomainPolicy. The pairing indicates the issuing CA considers
 its issuerDomainPolicy equivalent to the subject CA's
 subjectDomainPolicy.

Housley, et. al. Standards Track [Page 31] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 The issuing CA's users may accept an issuerDomainPolicy for certain
 applications. The policy mapping tells the issuing CA's users which
 policies associated with the subject CA are comparable to the policy
 they accept.
 This extension may be supported by CAs and/or applications, and it
 MUST be non-critical.
 id-ce-policyMappings OBJECT IDENTIFIER ::=  { id-ce 33 }
 PolicyMappings ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {
      issuerDomainPolicy      CertPolicyId,
      subjectDomainPolicy     CertPolicyId }

4.2.1.7 Subject Alternative Name

 The subject alternative names extension allows additional identities
 to be bound to the subject of the certificate.  Defined options
 include an Internet electronic mail address, a DNS name, an IP
 address, and a uniform resource identifier (URI).  Other options
 exist, including completely local definitions.  Multiple name forms,
 and multiple instances of each name form, may be included.  Whenever
 such identities are to be bound into a certificate, the subject
 alternative name (or issuer alternative name) extension MUST be used.
 Because the subject alternative name is considered to be
 definitiviely bound to the public key, all parts of the subject
 alternative name MUST be verified by the CA.
 Further, if the only subject identity included in the certificate is
 an alternative name form (e.g., an electronic mail address), then the
 subject distinguished name MUST be empty (an empty sequence), and the
 subjectAltName extension MUST be present. If the subject field
 contains an empty sequence, the subjectAltName extension MUST be
 marked critical.
 When the subjectAltName extension contains an Internet mail address,
 the address MUST be included as an rfc822Name. The format of an
 rfc822Name is an "addr-spec" as defined in RFC 822 [RFC 822]. An
 addr-spec has the form "local-part@domain". Note that an addr-spec
 has no phrase (such as a common name) before it, has no comment (text
 surrounded in parentheses) after it, and is not surrounded by "<" and
 ">". Note that while upper and lower case letters are allowed in an
 RFC 822 addr-spec, no significance is attached to the case.
 When the subjectAltName extension contains a iPAddress, the address
 MUST be stored in the octet string in "network byte order," as
 specified in RFC 791 [RFC 791]. The least significant bit (LSB) of

Housley, et. al. Standards Track [Page 32] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 each octet is the LSB of the corresponding byte in the network
 address. For IP Version 4, as specified in RFC 791, the octet string
 MUST contain exactly four octets.  For IP Version 6, as specified in
 RFC 1883, the octet string MUST contain exactly sixteen octets [RFC
 1883].
 When the subjectAltName extension contains a domain name service
 label, the domain name MUST be stored in the dNSName (an IA5String).
 The name MUST be in the "preferred name syntax," as specified by RFC
 1034 [RFC 1034]. Note that while upper and lower case letters are
 allowed in domain names, no signifigance is attached to the case.  In
 addition, while the string " " is a legal domain name, subjectAltName
 extensions with a dNSName " " are not permitted.  Finally, the use of
 the DNS representation for Internet mail addresses (wpolk.nist.gov
 instead of wpolk@nist.gov) is not permitted; such identities are to
 be encoded as rfc822Name.
 When the subjectAltName extension contains a URI, the name MUST be
 stored in the uniformResourceIdentifier (an IA5String). The name MUST
 be a non-relative URL, and MUST follow the URL syntax and encoding
 rules specified in [RFC 1738].  The name must include both a scheme
 (e.g., "http" or "ftp") and a scheme-specific-part.  The scheme-
 specific-part must include a fully qualified domain name or IP
 address as the host.
 As specified in [RFC 1738], the scheme name is not case-sensitive
 (e.g., "http" is equivalent to "HTTP").  The host part is also not
 case-sensitive, but other components of the scheme-specific-part may
 be case-sensitive. When comparing URIs, conforming implementations
 MUST compare the scheme and host without regard to case, but assume
 the remainder of the scheme-specific-part is case sensitive.
 Subject alternative names may be constrained in the same manner as
 subject distinguished names using the name constraints extension as
 described in section 4.2.1.11.
 If the subjectAltName extension is present, the sequence MUST contain
 at least one entry.  Unlike the subject field, conforming CAs MUST
 NOT issue certificates with subjectAltNames containing empty
 GeneralName fields. For example, an rfc822Name is represented as an
 IA5String. While an empty string is a valid IA5String, such an
 rfc822Name is not permitted by this profile.  The behavior of clients
 that encounter such a certificate when processing a certificication
 path is not defined by this profile.

Housley, et. al. Standards Track [Page 33] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 Finally, the semantics of subject alternative names that include
 wildcard characters (e.g., as a placeholder for a set of names) are
 not addressed by this specification.  Applications with specific
 requirements may use such names but shall define the semantics.
    id-ce-subjectAltName OBJECT IDENTIFIER ::=  { id-ce 17 }
    SubjectAltName ::= GeneralNames
    GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName
    GeneralName ::= CHOICE {
         otherName                       [0]     OtherName,
         rfc822Name                      [1]     IA5String,
         dNSName                         [2]     IA5String,
         x400Address                     [3]     ORAddress,
         directoryName                   [4]     Name,
         ediPartyName                    [5]     EDIPartyName,
         uniformResourceIdentifier       [6]     IA5String,
         iPAddress                       [7]     OCTET STRING,
         registeredID                    [8]     OBJECT IDENTIFIER}
    OtherName ::= SEQUENCE {
         type-id    OBJECT IDENTIFIER,
         value      [0] EXPLICIT ANY DEFINED BY type-id }
    EDIPartyName ::= SEQUENCE {
         nameAssigner            [0]     DirectoryString OPTIONAL,
         partyName               [1]     DirectoryString }

4.2.1.8 Issuer Alternative Names

 As with 4.2.1.7, this extension is used to associate Internet style
 identities with the certificate issuer. Issuer alternative names MUST
 be encoded as in 4.2.1.7.
 Where present, this extension SHOULD NOT be marked critical.
    id-ce-issuerAltName OBJECT IDENTIFIER ::=  { id-ce 18 }
    IssuerAltName ::= GeneralNames

4.2.1.9 Subject Directory Attributes

 The subject directory attributes extension is not recommended as an
 essential part of this profile, but it may be used in local
 environments.  This extension MUST be non-critical.

Housley, et. al. Standards Track [Page 34] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 id-ce-subjectDirectoryAttributes OBJECT IDENTIFIER ::=  { id-ce 9 }
 SubjectDirectoryAttributes ::= SEQUENCE SIZE (1..MAX) OF Attribute

4.2.1.10 Basic Constraints

 The basic constraints extension identifies whether the subject of the
 certificate is a CA and how deep a certification path may exist
 through that CA.
 The pathLenConstraint field is meaningful only if cA is set to TRUE.
 In this case, it gives the maximum number of CA certificates that may
 follow this certificate in a certification path. A value of zero
 indicates that only an end-entity certificate may follow in the path.
 Where it appears, the pathLenConstraint field MUST be greater than or
 equal to zero. Where pathLenConstraint does not appear, there is no
 limit to the allowed length of the certification path.
 This extension MUST appear as a critical extension in all CA
 certificates.  This extension SHOULD NOT appear in end entity
 certificates.
 id-ce-basicConstraints OBJECT IDENTIFIER ::=  { id-ce 19 }
 BasicConstraints ::= SEQUENCE {
      cA                      BOOLEAN DEFAULT FALSE,
      pathLenConstraint       INTEGER (0..MAX) OPTIONAL }

4.2.1.11 Name Constraints

 The name constraints extension, which MUST be used only in a CA
 certificate, indicates a name space within which all subject names in
 subsequent certificates in a certification path shall be located.
 Restrictions may apply to the subject distinguished name or subject
 alternative names.  Restrictions apply only when the specified name
 form is present. If no name of the type is in the certificate, the
 certificate is acceptable.
 Restrictions are defined in terms of permitted or excluded name
 subtrees.  Any name matching a restriction in the excludedSubtrees
 field is invalid regardless of information appearing in the
 permittedSubtrees.  This extension MUST be critical.
 Within this profile, the minimum and maximum fields are not used with
 any name forms, thus minimum is always zero, and maximum is always
 absent.

Housley, et. al. Standards Track [Page 35] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 For URIs, the constraint applies to the host part of the name. The
 constraint may specify a host or a domain.  Examples would be
 "foo.bar.com";  and ".xyz.com".  When the the constraint begins with
 a period, it may be expanded with one or more subdomains.  That is,
 the constraint ".xyz.com" is satisfied by both abc.xyz.com and
 abc.def.xyz.com.  However, the constraint ".xyz.com" is not satisfied
 by "xyz.com".  When the constraint does not begin with a period, it
 specifies a host.
 A name constraint for Internat mail addresses may specify a
 particular mailbox, all addresses at a particular host, or all
 mailboxes in a domain.  To indicate a particular mailbox, the
 constraint is the complete mail address.  For example, "root@xyz.com"
 indicates the root mailbox on the host "xyz.com". To indicate all
 Internet mail addresses on a particular host, the constraint is
 specified as the host name.  For example, the constraint "xyz.com" is
 satisfied by any mail address at the host "xyz.com". To specify any
 address within a domain, the constraint is specified with a leading
 period (as with URIs).  For example, ".xyz.com" indicates all the
 Internet mail addresses in the domain "xyz.com", but Internet mail
 addresses on the host "xyz.com".
 DNS name restrictions are expressed as foo.bar.com. Any subdomain
 satisfies the name constraint. For example, www.foo.bar.com would
 satisfy the constraint but bigfoo.bar.com would not.
 Legacy implementations exist where an RFC 822 name is embedded in the
 subject distinguished name in an attribute of type EmailAddress (see
 sec. 4.1.2.6). When rfc822 names are constrained, but the certificate
 does not include a subject alternative name, the rfc822 name
 constraint MUST be applied to the attribute of type EmailAddress in
 the subject distinguished name.  The ASN.1 syntax for EmailAddress
 and the corresponding OID are supplied in Appendix A and B.
 Restrictions of the form directoryName MUST be applied to the subject
 field in the certificate and to the subjectAltName extensions of type
 directoryName. Restrictions of the form x400Address MUST be applied
 to subjectAltName extensions of type x400Address.
 When applying restrictions of the form directoryName, an
 implementation MUST compare DN attributes.  At a minimum,
 implementations MUST perform the DN comparison rules specified in
 Section 4.1.2.4.  CAs issuing certificates with a restriction of the
 form directoryName SHOULD NOT rely on implementation of the full ISO
 DN name comparison algorithm.  This implies name restrictions shall
 be stated identically to the encoding used in the subject field or
 subjectAltName extension.

Housley, et. al. Standards Track [Page 36] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 The syntax of iPAddress MUST be as described in section 4.2.1.7 with
 the following additions specifically for Name Constraints.  For IPv4
 addresses, the ipAddress field of generalName MUST contain eight (8)
 octets, encoded in the style of RFC 1519 (CIDR) to represent an
 address range.[RFC 1519]  For IPv6 addresses, the ipAddress field
 MUST contain 32 octets similarly encoded.  For example, a name
 constraint for "class C" subnet 10.9.8.0 shall be represented as the
 octets 0A 09 08 00 FF FF FF 00, representing the CIDR notation
 10.9.8.0/255.255.255.0.
 The syntax and semantics for name constraints for otherName,
 ediPartyName, and registeredID are not defined by this specification.
    id-ce-nameConstraints OBJECT IDENTIFIER ::=  { id-ce 30 }
    NameConstraints ::= SEQUENCE {
         permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
         excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }
    GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
    GeneralSubtree ::= SEQUENCE {
         base                    GeneralName,
         minimum         [0]     BaseDistance DEFAULT 0,
         maximum         [1]     BaseDistance OPTIONAL }
    BaseDistance ::= INTEGER (0..MAX)

4.2.1.12 Policy Constraints

 The policy constraints extension can be used in certificates issued
 to CAs. The policy constraints extension constrains path validation
 in two ways. It can be used to prohibit policy mapping or require
 that each certificate in a path contain an acceptable policy
 identifier.
 If the inhibitPolicyMapping field is present, the value indicates the
 number of additional certificates that may appear in the path before
 policy mapping is no longer permitted.  For example, a value of one
 indicates that policy mapping may be processed in certificates issued
 by the subject of this certificate, but not in additional
 certificates in the path.
 If the requireExplicitPolicy field is present, subsequent
 certificates shall include an acceptable policy identifier. The value
 of requireExplicitPolicy indicates the number of additional
 certificates that may appear in the path before an explicit policy is
 required.  An acceptable policy identifier is the identifier of a

Housley, et. al. Standards Track [Page 37] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 policy required by the user of the certification path or the
 identifier of a policy which has been declared equivalent through
 policy mapping.
 Conforming CAs MUST NOT issue certificates where policy constraints
 is a null sequence. That is, at least one of the inhibitPolicyMapping
 field or the requireExplicitPolicy field MUST be present. The
 behavior of clients that encounter a null policy constraints field is
 not addressed in this profile.
 This extension may be critical or non-critical.
 id-ce-policyConstraints OBJECT IDENTIFIER ::=  { id-ce 36 }
 PolicyConstraints ::= SEQUENCE {
      requireExplicitPolicy           [0] SkipCerts OPTIONAL,
      inhibitPolicyMapping            [1] SkipCerts OPTIONAL }
 SkipCerts ::= INTEGER (0..MAX)

4.2.1.13 Extended key usage field

 This field indicates one or more purposes for which the certified
 public key may be used, in addition to or in place of the basic
 purposes indicated in the key usage extension field.  This field is
 defined as follows:
 id-ce-extKeyUsage OBJECT IDENTIFIER ::= {id-ce 37}
 ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId
 KeyPurposeId ::= OBJECT IDENTIFIER
 Key purposes may be defined by any organization with a need. Object
 identifiers used to identify key purposes shall be assigned in
 accordance with IANA or ITU-T Rec. X.660 | ISO/IEC/ITU 9834-1.
 This extension may, at the option of the certificate issuer, be
 either critical or non-critical.
 If the extension is flagged critical, then the certificate MUST be
 used only for one of the purposes indicated.
 If the extension is flagged non-critical, then it indicates the
 intended purpose or purposes of the key, and may be used in finding
 the correct key/certificate of an entity that has multiple
 keys/certificates. It is an advisory field and does not imply that
 usage of the key is restricted by the certification authority to the

Housley, et. al. Standards Track [Page 38] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 purpose indicated. Certificate using applications may nevertheless
 require that a particular purpose be indicated in order for the
 certificate to be acceptable to that application.
 If a certificate contains both a critical key usage field and a
 critical extended key usage field, then both fields MUST be processed
 independently and the certificate MUST only be used for a purpose
 consistent with both fields.  If there is no purpose consistent with
 both fields, then the certificate MUST NOT be used for any purpose.
 The following key usage purposes are defined by this profile:
 id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }
 id-kp-serverAuth              OBJECT IDENTIFIER ::=   {id-kp 1}
 -- TLS Web server authentication
 -- Key usage bits that may be consistent: digitalSignature,
 --                         keyEncipherment or keyAgreement
 --
 id-kp-clientAuth              OBJECT IDENTIFIER ::=   {id-kp 2}
 -- TLS Web client authentication
 -- Key usage bits that may be consistent: digitalSignature and/or
 --                            keyAgreement
 --
 id-kp-codeSigning             OBJECT IDENTIFIER ::=   {id-kp 3}
 -- Signing of downloadable executable code
 -- Key usage bits that may be consistent: digitalSignature
 --
 id-kp-emailProtection         OBJECT IDENTIFIER ::=   {id-kp 4}
 -- E-mail protection
 -- Key usage bits that may be consistent: digitalSignature,
 --                         nonRepudiation, and/or (keyEncipherment
 --                         or keyAgreement)
 --
 id-kp-timeStamping    OBJECT IDENTIFIER ::= { id-kp 8 }
 -- Binding the hash of an object to a time from an agreed-upon time
 -- source. Key usage bits that may be consistent: digitalSignature,
 --                         nonRepudiation

4.2.1.14 CRL Distribution Points

 The CRL distribution points extension identifies how CRL information
 is obtained.  The extension SHOULD be non-critical, but this profile
 recommends support for this extension by CAs and applications.
 Further discussion of CRL management is contained in section 5.

Housley, et. al. Standards Track [Page 39] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 If the cRLDistributionPoints extension contains a
 DistributionPointName of type URI, the following semantics MUST be
 assumed: the URI is a pointer to the current CRL for the associated
 reasons and will be issued by the associated cRLIssuer.  The expected
 values for the URI are those defined in 4.2.1.7. Processing rules for
 other values are not defined by this specification.  If the
 distributionPoint omits reasons, the CRL MUST include revocations for
 all reasons. If the distributionPoint omits cRLIssuer, the CRL MUST
 be issued by the CA that issued the certificate.
 id-ce-cRLDistributionPoints OBJECT IDENTIFIER ::=  { id-ce 31 }
 cRLDistributionPoints ::= {
      CRLDistPointsSyntax }
 CRLDistPointsSyntax ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint
 DistributionPoint ::= SEQUENCE {
      distributionPoint       [0]     DistributionPointName OPTIONAL,
      reasons                 [1]     ReasonFlags OPTIONAL,
      cRLIssuer               [2]     GeneralNames OPTIONAL }
 DistributionPointName ::= CHOICE {
      fullName                [0]     GeneralNames,
      nameRelativeToCRLIssuer [1]     RelativeDistinguishedName }
 ReasonFlags ::= BIT STRING {
      unused                  (0),
      keyCompromise           (1),
      cACompromise            (2),
      affiliationChanged      (3),
      superseded              (4),
      cessationOfOperation    (5),
      certificateHold         (6) }

4.2.2 Private Internet Extensions

 This section defines one new extension for use in the Internet Public
 Key Infrastructure.  This extension may be used to direct
 applications to identify an on-line validation service supporting the
 issuing CA.  As the information may be available in multiple forms,
 each extension is a sequence of IA5String values, each of which
 represents a URI.  The URI implicitly specifies the location and
 format of the information and the method for obtaining the
 information.

Housley, et. al. Standards Track [Page 40] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 An object identifier is defined for the private extension.  The
 object identifier associated with the private extension is defined
 under the arc id-pe within the id-pkix name space.  Any future
 extensions defined for the Internet PKI will also be defined under
 the arc id-pe.
    id-pkix  OBJECT IDENTIFIER  ::=
             { iso(1) identified-organization(3) dod(6) internet(1)
                     security(5) mechanisms(5) pkix(7) }
    id-pe  OBJECT IDENTIFIER  ::=  { id-pkix 1 }

4.2.2.1 Authority Information Access

 The authority information access extension indicates how to access CA
 information and services for the issuer of the certificate in which
 the extension appears. Information and services may include on-line
 validation services and CA policy data.  (The location of CRLs is not
 specified in this extension; that information is provided by the
 cRLDistributionPoints extension.)  This extension may be included in
 subject or CA certificates, and it MUST be non-critical.
 id-pe-authorityInfoAccess OBJECT IDENTIFIER ::= { id-pe 1 }
 AuthorityInfoAccessSyntax  ::=
         SEQUENCE SIZE (1..MAX) OF AccessDescription
 AccessDescription  ::=  SEQUENCE {
         accessMethod          OBJECT IDENTIFIER,
         accessLocation        GeneralName  }
 id-ad OBJECT IDENTIFIER ::= { id-pkix 48 }
 id-ad-caIssuers OBJECT IDENTIFIER ::= { id-ad 2 }
 Each entry in the sequence AuthorityInfoAccessSyntax describes the
 format and location of additional information about the CA who issued
 the certificate in which this extension appears.  The type and format
 of the information is specified by the accessMethod field; the
 accessLocation field specifies the location of the information.  The
 retrieval mechanism may be implied by the accessMethod or specified
 by accessLocation.
 This profile defines one OID for accessMethod. The id-ad-caIssuers
 OID is used when the additional information lists CAs that have
 issued certificates superior to the CA that issued the certificate

Housley, et. al. Standards Track [Page 41] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 containing this extension.  The referenced CA Issuers description is
 intended to aid certificate users in the selection of a certification
 path that terminates at a point trusted by the certificate user.
 When id-ad-caIssuers appears as accessInfoType, the accessLocation
 field describes the referenced description server and the access
 protocol to obtain the referenced description.  The accessLocation
 field is defined as a GeneralName, which can take several forms.
 Where the information is available via http, ftp, or ldap,
 accessLocation MUST be a uniformResourceIdentifier.  Where the
 information is available via the directory access protocol (dap),
 accessLocation MUST be a directoryName. When the information is
 available via electronic mail, accessLocation MUST be an rfc822Name.
 The semantics of other name forms of accessLocation (when
 accessMethod is id-ad-caIssuers) are not defined by this
 specification.
 Additional access descriptors may be defined in other PKIX
 specifications.

5 CRL and CRL Extensions Profile

 As described above, one goal of this X.509 v2 CRL profile is to
 foster the creation of an interoperable and reusable Internet PKI.
 To achieve this goal, guidelines for the use of extensions are
 specified, and some assumptions are made about the nature of
 information included in the CRL.
 CRLs may be used in a wide range of applications and environments
 covering a broad spectrum of interoperability goals and an even
 broader spectrum of operational and assurance requirements.  This
 profile establishes a common baseline for generic applications
 requiring broad interoperability.  The profile defines a baseline set
 of information that can be expected in every CRL.  Also, the profile
 defines common locations within the CRL for frequently used
 attributes as well as common representations for these attributes.
 This profile does not define any private Internet CRL extensions or
 CRL entry extensions.
 Environments with additional or special purpose requirements may
 build on this profile or may replace it.
 Conforming CAs are not required to issue CRLs if other revocation or
 certificate status mechanisms are provided.  Conforming CAs that
 issue CRLs MUST issue version 2 CRLs, and CAs MUST include the date
 by which the next CRL will be issued in the nextUpdate field (see

Housley, et. al. Standards Track [Page 42] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 sec. 5.1.2.5), the CRL number extension (see sec. 5.2.3) and the
 authority key identifier extension (see sec. 5.2.1).  Conforming
 applications are required to process version 1 and 2 CRLs.

5.1 CRL Fields

 The X.509 v2 CRL syntax is as follows.  For signature calculation,
 the data that is to be signed is ASN.1 DER encoded.  ASN.1 DER
 encoding is a tag, length, value encoding system for each element.
 CertificateList  ::=  SEQUENCE  {
      tbsCertList          TBSCertList,
      signatureAlgorithm   AlgorithmIdentifier,
      signatureValue       BIT STRING  }
 TBSCertList  ::=  SEQUENCE  {
      version                 Version OPTIONAL,
                                   -- if present, shall be v2
      signature               AlgorithmIdentifier,
      issuer                  Name,
      thisUpdate              Time,
      nextUpdate              Time OPTIONAL,
      revokedCertificates     SEQUENCE OF SEQUENCE  {
           userCertificate         CertificateSerialNumber,
           revocationDate          Time,
           crlEntryExtensions      Extensions OPTIONAL
                                         -- if present, shall be v2
                                }  OPTIONAL,
      crlExtensions           [0]  EXPLICIT Extensions OPTIONAL
                                         -- if present, shall be v2
                                }
  1. - Version, Time, CertificateSerialNumber, and Extensions
  2. - are all defined in the ASN.1 in section 4.1
  1. - AlgorithmIdentifier is defined in section 4.1.1.2
 The following items describe the use of the X.509 v2 CRL in the
 Internet PKI.

5.1.1 CertificateList Fields

 The CertificateList is a SEQUENCE of three required fields. The
 fields are described in detail in the following subsections.

Housley, et. al. Standards Track [Page 43] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

5.1.1.1 tbsCertList

 The first field in the sequence is the tbsCertList.  This field is
 itself a sequence containing the name of the issuer, issue date,
 issue date of the next list, the list of revoked certificates, and
 optional CRL extensions.  Further, each entry on the revoked
 certificate list is defined by a sequence of user certificate serial
 number, revocation date, and optional CRL entry extensions.

5.1.1.2 signatureAlgorithm

 The signatureAlgorithm field contains the algorithm identifier for
 the algorithm used by the CA to sign the CertificateList.  The field
 is of type AlgorithmIdentifier, which is defined in section 4.1.1.2.
 Section 7.2 lists the supported algorithms for this specification.
 Conforming CAs MUST use the algorithm identifiers presented in
 section 7.2 when signing with a supported signature algorithm.
 This field MUST contain the same algorithm identifier as the
 signature field in the sequence tbsCertList (see sec. 5.1.2.2).

5.1.1.3 signatureValue

 The signatureValue field contains a digital signature computed upon
 the ASN.1 DER encoded tbsCertList.  The ASN.1 DER encoded tbsCertList
 is used as the input to the signature function. This signature value
 is then ASN.1 encoded as a BIT STRING and included in the CRL's
 signatureValue field. The details of this process are specified for
 each of the supported algorithms in section 7.2.

5.1.2 Certificate List "To Be Signed"

 The certificate list to be signed, or TBSCertList, is a SEQUENCE of
 required and optional fields.  The required fields identify the CRL
 issuer, the algorithm used to sign the CRL, the date and time the CRL
 was issued, and the date and time by which the CA will issue the next
 CRL.
 Optional fields include lists of revoked certificates and CRL
 extensions.  The revoked certificate list is optional to support the
 case where a CA has not revoked any unexpired certificates that it
 has issued.  The profile requires conforming CAs to use the CRL
 extension cRLNumber in all CRLs issued.

Housley, et. al. Standards Track [Page 44] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

5.1.2.1 Version

 This optional field describes the version of the encoded CRL.  When
 extensions are used, as required by this profile, this field MUST be
 present and MUST specify version 2 (the integer value is 1).

5.1.2.2 Signature

 This field contains the algorithm identifier for the algorithm used
 to sign the CRL.  Section 7.2 lists OIDs for the most popular
 signature algorithms used in the Internet PKI.
 This field MUST contain the same algorithm identifier as the
 signatureAlgorithm field in the sequence CertificateList (see section
 5.1.1.2).

5.1.2.3 Issuer Name

 The issuer name identifies the entity who has signed and issued the
 CRL.  The issuer identity is carried in the issuer name field.
 Alternative name forms may also appear in the issuerAltName extension
 (see sec. 5.2.2).  The issuer name field MUST contain an X.500
 distinguished name (DN).  The issuer name field is defined as the
 X.501 type Name, and MUST follow the encoding rules for the issuer
 name field in the certificate (see sec. 4.1.2.4).

5.1.2.4 This Update

 This field indicates the issue date of this CRL. ThisUpdate may be
 encoded as UTCTime or GeneralizedTime.
 CAs conforming to this profile that issue CRLs MUST encode thisUpdate
 as UTCTime for dates through the year 2049. CAs conforming to this
 profile that issue CRLs MUST encode thisUpdate as GeneralizedTime for
 dates in the year 2050 or later.
 Where encoded as UTCTime, thisUpdate MUST be specified and
 interpreted as defined in section 4.1.2.5.1.  Where encoded as
 GeneralizedTime, thisUpdate MUST be specified and interpreted as
 defined in section 4.1.2.5.2.

5.1.2.5 Next Update

 This field indicates the date by which the next CRL will be issued.
 The next CRL could be issued before the indicated date, but it will
 not be issued any later than the indicated date. CAs SHOULD issue
 CRLs with a nextUpdate time equal to or later than all previous CRLs.
 nextUpdate may be encoded as UTCTime or GeneralizedTime.

Housley, et. al. Standards Track [Page 45] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 This profile requires inclusion of nextUpdate in all CRLs issued by
 conforming CAs. Note that the ASN.1 syntax of TBSCertList describes
 this field as OPTIONAL, which is consistent with the ASN.1 structure
 defined in [X.509]. The behavior of clients processing CRLs which
 omit nextUpdate is not specified by this profile.
 CAs conforming to this profile that issue CRLs MUST encode nextUpdate
 as UTCTime for dates through the year 2049. CAs conforming to this
 profile that issue CRLs MUST encode nextUpdate as GeneralizedTime for
 dates in the year 2050 or later.
 Where encoded as UTCTime, nextUpdate MUST be specified and
 interpreted as defined in section 4.1.2.5.1.  Where encoded as
 GeneralizedTime, nextUpdate MUST be specified and interpreted as
 defined in section 4.1.2.5.2.

5.1.2.6 Revoked Certificates

 Revoked certificates are listed.  The revoked certificates are named
 by their serial numbers.  Certificates revoked by the CA are uniquely
 identified by the certificate serial number.  The date on which the
 revocation occurred is specified.  The time for revocationDate MUST
 be expressed as described in section 5.1.2.4. Additional information
 may be supplied in CRL entry extensions; CRL entry extensions are
 discussed in section 5.3.

5.1.2.7 Extensions

 This field may only appear if the version is 2 (see sec. 5.1.2.1).
 If present, this field is a SEQUENCE of one or more CRL extensions.
 CRL extensions are discussed in section 5.2.

5.2 CRL Extensions

 The extensions defined by ANSI X9 and ISO/IEC/ITU for X.509 v2 CRLs
 [X.509] [X9.55] provide methods for associating additional attributes
 with CRLs.  The X.509 v2 CRL format also allows communities to define
 private extensions to carry information unique to those communities.
 Each extension in a CRL may be designated as critical or non-
 critical.  A CRL validation MUST fail if it encounters a critical
 extension which it does not know how to process.  However, an
 unrecognized non-critical extension may be ignored.  The following
 subsections present those extensions used within Internet CRLs.
 Communities may elect to include extensions in CRLs which are not
 defined in this specification. However, caution should be exercised
 in adopting any critical extensions in CRLs which might be used in a
 general context.

Housley, et. al. Standards Track [Page 46] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 Conforming CAs that issue CRLs are required to include the authority
 key identifier (see sec. 5.2.1) and the CRL number (see sec. 5.2.3)
 extensions in all CRLs issued.

5.2.1 Authority Key Identifier

 The authority key identifier extension provides a means of
 identifying the public key corresponding to the private key used to
 sign a CRL.  The identification can be based on either the key
 identifier (the subject key identifier in the CRL signer's
 certificate) or on the issuer name and serial number. This extension
 is especially useful where an issuer has more than one signing key,
 either due to multiple concurrent key pairs or due to changeover.
 Conforming CAs MUST use the key identifier method, and MUST include
 this extension in all CRLs issued.
 The syntax for this CRL extension is defined in section 4.2.1.1.

5.2.2 Issuer Alternative Name

 The issuer alternative names extension allows additional identities
 to be associated with the issuer of the CRL.  Defined options include
 an rfc822 name (electronic mail address), a DNS name, an IP address,
 and a URI.  Multiple instances of a name and multiple name forms may
 be included.  Whenever such identities are used, the issuer
 alternative name extension MUST be used.
 The issuerAltName extension SHOULD NOT be marked critical.
 The OID and syntax for this CRL extension are defined in section
 4.2.1.8.

5.2.3 CRL Number

 The CRL number is a non-critical CRL extension which conveys a
 monotonically increasing sequence number for each CRL issued by a CA.
 This extension allows users to easily determine when a particular CRL
 supersedes another CRL.  CAs conforming to this profile MUST include
 this extension in all CRLs.
 id-ce-cRLNumber OBJECT IDENTIFIER ::= { id-ce 20 }
 cRLNumber ::= INTEGER (0..MAX)

Housley, et. al. Standards Track [Page 47] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

5.2.4 Delta CRL Indicator

 The delta CRL indicator is a critical CRL extension that identifies a
 delta-CRL.  The use of delta-CRLs can significantly improve
 processing time for applications which store revocation information
 in a format other than the CRL structure.  This allows changes to be
 added to the local database while ignoring unchanged information that
 is already in the local database.
 When a delta-CRL is issued, the CAs MUST also issue a complete CRL.
 The value of BaseCRLNumber identifies the CRL number of the base CRL
 that was used as the starting point in the generation of this delta-
 CRL.  The delta-CRL contains the changes between the base CRL and the
 current CRL issued along with the delta-CRL.  It is the decision of a
 CA as to whether to provide delta-CRLs.  Again, a delta-CRL MUST NOT
 be issued without a corresponding complete CRL.  The value of
 CRLNumber for both the delta-CRL and the corresponding complete CRL
 MUST be identical.
 A CRL user constructing a locally held CRL from delta-CRLs MUST
 consider the constructed CRL incomplete and unusable if the CRLNumber
 of the received delta-CRL is more than one greater than the CRLnumber
 of the delta-CRL last processed.
 id-ce-deltaCRLIndicator OBJECT IDENTIFIER ::= { id-ce 27 }
 deltaCRLIndicator ::= BaseCRLNumber
 BaseCRLNumber ::= CRLNumber

5.2.5 Issuing Distribution Point

 The issuing distribution point is a critical CRL extension that
 identifies the CRL distribution point for a particular CRL, and it
 indicates whether the CRL covers revocation for end entity
 certificates only, CA  certificates only, or a limitied set of reason
 codes.  Although the extension is critical, conforming
 implementations are not required to support this extension.
 The CRL is signed using the CA's private key.  CRL Distribution
 Points do not have their own key pairs.  If the CRL is stored in the
 X.500 Directory, it is stored in the Directory entry corresponding to
 the CRL distribution point, which may be different than the Directory
 entry of the CA.

Housley, et. al. Standards Track [Page 48] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 The reason codes associated with a distribution point shall be
 specified in onlySomeReasons. If onlySomeReasons does not appear, the
 distribution point shall contain revocations for all reason codes.
 CAs may use CRL distribution points to partition the CRL on the basis
 of compromise and routine revocation.  In this case, the revocations
 with reason code keyCompromise (1) and cACompromise (2) appear in one
 distribution point, and the revocations with other reason codes
 appear in another distribution point.
 Where the issuingDistributionPoint extension contains a URL, the
 following semantics MUST be assumed: the object is a pointer to the
 most current CRL issued by this CA.  The URI schemes ftp, http,
 mailto [RFC1738] and ldap [RFC1778] are defined for this purpose.
 The URI MUST be an absolute, not relative, pathname and MUST specify
 the host.
 id-ce-issuingDistributionPoint OBJECT IDENTIFIER ::= { id-ce 28 }
 issuingDistributionPoint ::= SEQUENCE {
      distributionPoint       [0] DistributionPointName OPTIONAL,
      onlyContainsUserCerts   [1] BOOLEAN DEFAULT FALSE,
      onlyContainsCACerts     [2] BOOLEAN DEFAULT FALSE,
      onlySomeReasons         [3] ReasonFlags OPTIONAL,
      indirectCRL             [4] BOOLEAN DEFAULT FALSE }

5.3 CRL Entry Extensions

 The CRL entry extensions already defined by ANSI X9 and ISO/IEC/ITU
 for X.509 v2 CRLs provide methods for associating additional
 attributes with CRL entries [X.509] [X9.55].  The X.509 v2 CRL format
 also allows communities to define private CRL entry extensions to
 carry information unique to those communities.  Each extension in a
 CRL entry may be designated as critical or non-critical.  A CRL
 validation MUST fail if it encounters a critical CRL entry extension
 which it does not know how to process.  However, an unrecognized
 non-critical CRL entry extension may be ignored.  The following
 subsections present recommended extensions used within Internet CRL
 entries and standard locations for information.  Communities may
 elect to use additional CRL entry extensions; however, caution should
 be exercised in adopting any critical extensions in CRL entries which
 might be used in a general context.
 All CRL entry extensions used in this specification are non-critical.
 Support for these extensions is optional for conforming CAs and
 applications.  However, CAs that issue CRLs SHOULD include reason
 codes (see sec. 5.3.1) and invalidity dates (see sec. 5.3.3) whenever
 this information is available.

Housley, et. al. Standards Track [Page 49] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

5.3.1 Reason Code

 The reasonCode is a non-critical CRL entry extension that identifies
 the reason for the certificate revocation. CAs are strongly
 encouraged to include meaningful reason codes in CRL entries;
 however, the reason code CRL entry extension SHOULD be absent instead
 of using the unspecified (0) reasonCode value.
 id-ce-cRLReason OBJECT IDENTIFIER ::= { id-ce 21 }
  1. - reasonCode ::= { CRLReason }
 CRLReason ::= ENUMERATED {
      unspecified             (0),
      keyCompromise           (1),
      cACompromise            (2),
      affiliationChanged      (3),
      superseded              (4),
      cessationOfOperation    (5),
      certificateHold         (6),
      removeFromCRL           (8) }

5.3.2 Hold Instruction Code

 The hold instruction code is a non-critical CRL entry extension that
 provides a registered instruction identifier which indicates the
 action to be taken after encountering a certificate that has been
 placed on hold.
 id-ce-holdInstructionCode OBJECT IDENTIFIER ::= { id-ce 23 }
 holdInstructionCode ::= OBJECT IDENTIFIER
 The following instruction codes have been defined.  Conforming
 applications that process this extension MUST recognize the following
 instruction codes.
 holdInstruction    OBJECT IDENTIFIER ::=
                  { iso(1) member-body(2) us(840) x9-57(10040) 2 }
 id-holdinstruction-none   OBJECT IDENTIFIER ::= {holdInstruction 1}
 id-holdinstruction-callissuer
                           OBJECT IDENTIFIER ::= {holdInstruction 2}
 id-holdinstruction-reject OBJECT IDENTIFIER ::= {holdInstruction 3}
 Conforming applications which encounter an id-holdinstruction-
 callissuer MUST call the certificate issuer or reject the
 certificate.  Conforming applications which encounter an id-

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 holdinstruction-reject MUST reject the certificate. The hold
 instruction id-holdinstruction-none is semantically equivalent to the
 absence of a holdInstructionCode, and its use is strongly deprecated
 for the Internet PKI.

5.3.3 Invalidity Date

 The invalidity date is a non-critical CRL entry extension that
 provides the date on which it is known or suspected that the private
 key was compromised or that the certificate otherwise became invalid.
 This date may be earlier than the revocation date in the CRL entry,
 which is the date at which the CA processed the revocation. When a
 revocation is first posted by a CA in a CRL, the invalidity date may
 precede the date of issue of earlier CRLs, but the revocation date
 SHOULD NOT precede the date of issue of earlier CRLs.  Whenever this
 information is available, CAs are strongly encouraged to share it
 with CRL users.
 The GeneralizedTime values included in this field MUST be expressed
 in Greenwich Mean Time (Zulu), and MUST be specified and interpreted
 as defined in section 4.1.2.5.2.
 id-ce-invalidityDate OBJECT IDENTIFIER ::= { id-ce 24 }
 invalidityDate ::=  GeneralizedTime

5.3.4 Certificate Issuer

 This CRL entry extension identifies the certificate issuer associated
 with an entry in an indirect CRL, i.e. a CRL that has the indirectCRL
 indicator set in its issuing distribution point extension. If this
 extension is not present on the first entry in an indirect CRL, the
 certificate issuer defaults to the CRL issuer. On subsequent entries
 in an indirect CRL, if this extension is not present, the certificate
 issuer for the entry is the same as that for the preceding entry.
 This field is defined as follows:
 id-ce-certificateIssuer   OBJECT IDENTIFIER ::= { id-ce 29 }
 certificateIssuer ::=     GeneralNames
 If used by conforming CAs that issue CRLs, this extension is always
 critical.  If an implementation ignored this extension it could not
 correctly attribute CRL entries to certificates.  This specification
 RECOMMENDS that implementations recognize this extension.

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6 Certification Path Validation

 Certification path validation procedures for the Internet PKI are
 based on section 12.4.3 of [X.509].  Certification path processing
 verifies the binding between the subject distinguished name and/or
 subject alternative name and subject public key.  The binding is
 limited by constraints which are specified in the certificates which
 comprise the path. The basic constraints and policy constraints
 extensions allow the certification path processing logic to automate
 the decision making process.
 This section describes an algorithm for validating certification
 paths.  Conforming implementations of this specification are not
 required to implement this algorithm, but MUST be functionally
 equivalent to the external behavior resulting from this procedure.
 Any algorithm may be used by a particular implementation so long as
 it derives the correct result.
 In section 6.1, the text describes basic path validation. This text
 assumes that all valid paths begin with certificates issued by a
 single "most-trusted CA". The algorithm requires the public key of
 the CA, the CA's name, the validity period of the public key, and any
 constraints upon the set of paths which may be validated using this
 key.
 The "most-trusted CA" is a matter of policy: it could be a root CA in
 a hierarchical PKI; the CA that issued the verifier's own
 certificate(s); or any other CA in a network PKI.  The path
 validation procedure is the same regardless of the choice of "most-
 trusted CA."
 section 6.2 describes extensions to the basic path validation
 algorithm. Two specific cases are discussed: the case where paths may
 begin with one of several trusted CAs; and where compatibility with
 the PEM architecture is required.

6.1 Basic Path Validation

 The text assumes that the trusted public key (and related
 information) is contained in a "self-signed" certificate. This
 simplifies the description of the path processing procedure.  Note
 that the signature on the self-signed certificate does not provide
 any security services.  The trusted public key (and related
 information) may be obtained in other formats; the information is
 trusted because of other procedures used to obtain and protect it.

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 The goal of path validation is to verify the binding between a
 subject distinguished name or subject alternative name and subject
 public key, as represented in the "end entity" certificate, based on
 the public key of the "most-trusted CA".  This requires obtaining a
 sequence of certificates that support that binding.  The procedures
 performed to obtain this sequence is outside the scope of this
 section.
 The following text also assumes that certificates do not use subject
 or unique identifier fields or private critical extensions, as
 recommended within this profile.  However, if these components appear
 in certificates, they MUST be processed.  Finally, policy qualifiers
 are also neglected for the sake of clarity.
 A certification path is a sequence of n certificates where:
  • for all x in {1,(n-1)}, the subject of certificate x is the

issuer of certificate x+1.

  • certificate x=1 is the the self-signed certificate, and
  • certificate x=n is the end entity certificate.
 This section assumes the following inputs are provided to the path
 processing logic:
    (a)  a certification path of length n;
    (b)  a set of initial policy identifiers (each comprising a
    sequence of policy element identifiers), which identifies one or
    more certificate policies, any one of which would be acceptable
    for the purposes of certification path processing, or the special
    value "any-policy";
    (c)  the current date/time (if not available internally to the
    certification path processing module); and
    (d)  the time, T, for which the validity of the path should be
    determined.  (This may be the current date/time, or some point in
    the past.)
 From the inputs, the procedure intializes five state variables:
    (a)  acceptable policy set:  A set of certificate policy
    identifiers comprising the policy or policies recognized by the
    public key user together with policies deemed equivalent through
    policy mapping. The initial value of the acceptable policy set is
    the special value "any-policy".

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    (b)  constrained subtrees:  A set of root names defining a set of
    subtrees within which all subject names in subsequent certificates
    in the certification path shall fall. The initial value is
    "unbounded".
    (c)  excluded subtrees:  A set of root names defining a set of
    subtrees within which no subject name in subsequent certificates
    in the certification path may fall. The initial value is "empty".
    (d)  explicit policy: an integer which indicates if an explicit
    policy identifier is required. The integer indicates the first
    certificate in the path where this requirement is imposed. Once
    set, this variable may be decreased, but may not be increased.
    (That is, if a certificate in the path requires explicit policy
    identifiers, a later certificate can not remove this requirement.)
    The initial value is n+1.
    (e)  policy mapping: an integer which indicates if policy mapping
    is permitted.  The integer indicates the last certificate on which
    policy mapping may be applied.  Once set, this variable may be
    decreased, but may not be increased. (That is, if a certificate in
    the path specifies policy mapping is not permitted, it can not be
    overriden by a later certificate.) The initial value is n+1.
 The actions performed by the path processing software for each
 certificate i=1 through n are described below.  The self-signed
 certificate is certificate i=1, the end entity certificate is i=n.
 The processing is performed sequentially, so that processing
 certificate i affects the state variables for processing certificate
 (i+1). Note that actions (h) through (m) are not applied to the end
 entity certificate (certificate n).
 The path processing actions to be performed are:
    (a)  Verify the basic certificate information, including:
       (1) the certificate was signed using the subject public key
       from certificate i-1 (in the special case i=1, this step may be
       omitted; if not, use the subject public key from the same
       certificate),
       (2) the certificate validity period includes time T,
       (3) the certificate had not been revoked at time T and is not
       currently on hold status that commenced before time T, (this
       may be determined by obtaining the appropriate CRL or status
       information, or by out-of-band mechanisms), and

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       (4) the subject and issuer names chain correctly (that is, the
       issuer of this certificate was the subject of the previous
       certificate.)
    (b)  Verify that the subject name and subjectAltName extension
    (critical or noncritical) is consistent with the constrained
    subtrees state variables.
    (c)  Verify that the subject name and subjectAltName extension
    (critical or noncritical) is consistent with the excluded subtrees
    state variables.
    (d)  Verify that policy information is consistent with the initial
    policy set:
       (1) if the explicit policy state variable is less than or equal
       to i, a policy identifier in the certificate shall be in the
       initial policy set; and
       (2) if the policy mapping variable is less than or equal to i,
       the policy identifier may not be mapped.
    (e)  Verify that policy information is consistent with the
    acceptable policy set:
       (1) if the certificate policies extension is marked critical,
       the intersection of the policies extension and the acceptable
       policy set shall be non-null;
       (2) the acceptable policy set is assigned the resulting
       intersection as its new value.
    (g) Verify that the intersection of the acceptable policy set and
    the initial policy set is non-null.
    (h)  Recognize and process any other critical extension present in
    the certificate.
    (i) Verify that the certificate is a CA certificate (as specified
    in a basicConstraints extension or as verified out-of-band).
    (j)  If permittedSubtrees is present in the certificate, set the
    constrained subtrees state variable to the intersection of its
    previous value and the value indicated in the extension field.
    (k)  If excludedSubtrees is present in the certificate, set the
    excluded subtrees state variable to the union of its previous
    value and the value indicated in the extension field.

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    (l)  If a policy constraints extension is included in the
    certificate, modify the explicit policy and policy mapping state
    variables as follows:
       (1) If requireExplicitPolicy is present and has value r, the
       explicit policy state variable is set to the minimum of its
       current value and the sum of r and i (the current certificate
       in the sequence).
       (2) If inhibitPolicyMapping is present and has value q, the
       policy mapping state variable is set to the minimum of its
       current value and the sum of q and i (the current certificate
       in the sequence).
    (m) If a key usage extension is marked critical, ensure the
    keyCertSign bit is set.
 If any one of the above checks fail, the procedure terminates,
 returning a failure indication and an appropriate reason.  If none of
 the above checks fail on the end-entity certificate, the procedure
 terminates, returning a success indication together with the set of
 all policy qualifier values encountered in the set of certificates.

6.2 Extending Path Validation

 The path validation algorithm presented in 6.1 is based on several
 simplifying assumptions (e.g., a single trusted CA that starts all
 valid paths). This algorithm may be extended for cases where the
 assumptions do not hold.
 This procedure may be extended for multiple trusted CAs by providing
 a set of self-signed certificates to the validation module.  In this
 case, a valid path could begin with any one of the self-signed
 certificates.  Limitations in the trust paths for any particular key
 may be incorporated into the self-signed certificate's extensions. In
 this way, the self-signed certificates permit the path validation
 module to automatically incorporate local security policy and
 requirements.
 It is also possible to specify an extended version of the above
 certification path processing procedure which results in default
 behavior identical to the rules of PEM [RFC 1422].  In this extended
 version, additional inputs to the procedure are a list of one or more
 Policy Certification Authorities (PCAs) names and an indicator of the
 position in the certification path where the PCA is expected.  At the
 nominated PCA position, the CA name is compared against this list.
 If a recognized PCA name is found, then a constraint of
 SubordinateToCA is implicitly assumed for the remainder of the

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 certification path and processing continues.  If no valid PCA name is
 found, and if the certification path cannot be validated on the basis
 of identified policies, then the certification path is considered
 invalid.

7 Algorithm Support

 This section describes cryptographic algorithms which may be used
 with this profile.  The section describes one-way hash functions and
 digital signature algorithms which may be used to sign certificates
 and CRLs, and identifies OIDs for public keys contained in a
 certificate.
 Conforming CAs and applications are not required to support the
 algorithms or algorithm identifiers described in this section.
 However, conforming CAs and applications that use the algorithms
 identified here MUST support them as specified.

7.1 One-way Hash Functions

 This section identifies one-way hash functions for use in the
 Internet PKI.  One-way hash functions are also called message digest
 algorithms. SHA-1 is the preferred one-way hash function for the
 Internet PKI.  However, PEM uses MD2 for certificates [RFC 1422] [RFC
 1423] and MD5 is used in other legacy applications.  For this reason,
 MD2 and MD5 are included in this profile.

7.1.1 MD2 One-way Hash Function

 MD2 was developed by Ron Rivest for RSA Data Security. RSA Data
 Security has not placed the MD2 algorithm in the public domain.
 Rather, RSA Data Security has granted license to use MD2 for non-
 commercial Internet Privacy-Enhanced Mail.  For this reason, MD2 may
 continue to be used with PEM certificates, but SHA-1 is preferred.
 MD2 produces a 128-bit "hash" of the input.  MD2 is fully described
 in RFC 1319 [RFC 1319].
 At the Selected Areas in Cryptography '95 conference in May 1995,
 Rogier and Chauvaud presented an attack on MD2 that can nearly find
 collisions [RC95].  Collisions occur when one can find two different
 messages that generate the same message digest.  A checksum operation
 in MD2 is the only remaining obstacle to the success of the attack.
 For this reason, the use of MD2 for new applications is discouraged.
 It is still reasonable to use MD2 to verify existing signatures, as
 the ability to find collisions in MD2 does not enable an attacker to
 find new messages having a previously computed hash value.

Housley, et. al. Standards Track [Page 57] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

7.1.2 MD5 One-way Hash Function

 MD5 was developed by Ron Rivest for RSA Data Security. RSA Data
 Security has placed the MD5 algorithm in the public domain.  MD5
 produces a 128-bit "hash" of the input.  MD5 is fully described in
 RFC 1321 [RFC 1321].
 Den Boer and Bosselaers [DB94] have found pseudo-collisions for MD5,
 but there are no other known cryptanalytic results.  The use of MD5
 for new applications is discouraged.  It is still reasonable to use
 MD5 to verify existing signatures.

7.1.3 SHA-1 One-way Hash Function

 SHA-1 was developed by the U.S. Government.  SHA-1 produces a 160-bit
 "hash" of the input. SHA-1 is fully described in FIPS 180-1 [FIPS
 180-1].
 SHA-1 is the one-way hash function of choice for use with both the
 RSA and DSA signature algorithms (see sec. 7.2).

7.2 Signature Algorithms

 Certificates and CRLs described by this standard may be signed with
 any public key signature algorithm.  The certificate or CRL indicates
 the algorithm through an algorithm identifier which appears in the
 signatureAlgorithm field in a Certificate or CertificateList.  This
 algorithm identifier is an OID and has optionally associated
 parameters.  This section identifies algorithm identifiers and
 parameters that shall be used in the signatureAlgorithm field in a
 Certificate or CertificateList.
 RSA and DSA are the most popular signature algorithms used in the
 Internet.  Signature algorithms are always used in conjunction with a
 one-way hash function identified in section 7.1.
 The signature algorithm and one-way hash function used to sign a
 certificate or CRL is indicated by use of an algorithm identifier.
 An algorithm identifier is an OID, and may include associated
 parameters.  This section identifies OIDS for RSA and DSA.  The
 contents of the parameters component for each algorithm vary; details
 are provided for each algorithm.
 The data to be signed (e.g., the one-way hash function output value)
 is formatted for the signature algorithm to be used.  Then, a private
 key operation (e.g., RSA encryption) is performed to generate the

Housley, et. al. Standards Track [Page 58] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 signature value.  This signature value is then ASN.1 encoded as a BIT
 STRING and included in the Certificate or CertificateList in the
 signature field.

7.2.1 RSA Signature Algorithm

 A patent statement regarding the RSA algorithm can be found at the
 end of this profile.
 The RSA algorithm is named for its inventors: Rivest, Shamir, and
 Adleman.  This profile includes three signature algorithms based on
 the RSA asymmetric encryption algorithm. The signature algorithms
 combine RSA with either the MD2, MD5, or the SHA-1 one-way hash
 functions.
 The signature algorithm with MD2 and the RSA encryption algorithm is
 defined in PKCS #1 [RFC 2313].  As defined in RFC 2313, the ASN.1 OID
 used to identify this signature algorithm is:
      md2WithRSAEncryption OBJECT IDENTIFIER  ::=  {
          iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
          pkcs-1(1) 2  }
 The signature algorithm with MD5 and the RSA encryption algorithm is
 defined in PKCS #1 [RFC 2313].  As defined in RFC 2313, the ASN.1 OID
 used to identify this signature algorithm is:
      md5WithRSAEncryption OBJECT IDENTIFIER  ::=  {
          iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
          pkcs-1(1) 4  }
 The signature algorithm with SHA-1 and the RSA encryption algorithm
 is implemented using the padding and encoding conventions described
 in PKCS #1 [RFC 2313]. The message digest is computed using the SHA-1
 hash algorithm.  The ASN.1 object identifier used to identify this
 signature algorithm is:
      sha-1WithRSAEncryption OBJECT IDENTIFIER  ::=  {
          iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
          pkcs-1(1) 5  }
 When any of these three OIDs appears within the ASN.1 type
 AlgorithmIdentifier, the parameters component of that type shall be
 the ASN.1 type NULL.
 The RSA signature generation process and the encoding of the result
 is described in detail in RFC 2313.

Housley, et. al. Standards Track [Page 59] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

7.2.2 DSA Signature Algorithm

 A patent statement regarding the DSA can be found at the end of this
 profile.
 The Digital Signature Algorithm (DSA) is also called the Digital
 Signature Standard (DSS).  DSA was developed by the U.S. Government,
 and DSA is used in conjunction with the the SHA-1 one-way hash
 function.  DSA is fully described in FIPS 186 [FIPS 186].  The ASN.1
 OIDs used to identify this signature algorithm are:
         id-dsa-with-sha1 ID  ::=  {
                 iso(1) member-body(2) us(840) x9-57 (10040)
                 x9cm(4) 3 }
 Where the id-dsa-with-sha1 algorithm identifier appears as the
 algorithm field in an AlgorithmIdentifier, the encoding shall omit
 the parameters field.  That is, the AlgorithmIdentifier shall be a
 SEQUENCE of one component - the OBJECT IDENTIFIER id-dsa-with-sha1.
 The DSA parameters in the subjectPublicKeyInfo field of the
 certificate of the issuer shall apply to the verification of the
 signature.
 When signing, the DSA algorithm generates two values.  These values
 are commonly referred to as r and s.  To easily transfer these two
 values as one signature, they shall be ASN.1 encoded using the
 following ASN.1 structure:
         Dss-Sig-Value  ::=  SEQUENCE  {
                 r       INTEGER,
                 s       INTEGER  }

7.3 Subject Public Key Algorithms

 Certificates described by this profile may convey a public key for
 any public key algorithm. The certificate indicates the algorithm
 through an algorithm identifier.  This algorithm identifier is an OID
 and optionally associated parameters.
 This section identifies preferred OIDs and parameters for the RSA,
 DSA, and Diffie-Hellman algorithms.  Conforming CAs shall use the
 identified OIDs when issuing certificates containing public keys for
 these algorithms. Conforming applications supporting any of these
 algorithms shall, at a minimum, recognize the OID identified in this
 section.

Housley, et. al. Standards Track [Page 60] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

7.3.1 RSA Keys

 The OID rsaEncryption identifies RSA public keys.
      pkcs-1 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
                     rsadsi(113549) pkcs(1) 1 }
      rsaEncryption OBJECT IDENTIFIER ::=  { pkcs-1 1}
 The rsaEncryption OID is intended to be used in the algorithm field
 of a value of type AlgorithmIdentifier. The parameters field shall
 have ASN.1 type NULL for this algorithm identifier.
 The RSA public key shall be encoded using the ASN.1 type
 RSAPublicKey:
    RSAPublicKey ::= SEQUENCE {
       modulus            INTEGER, -- n
       publicExponent     INTEGER  -- e -- }
 where modulus is the modulus n, and publicExponent is the public
 exponent e.  The DER encoded RSAPublicKey is the value of the BIT
 STRING subjectPublicKey.
 This OID is used in public key certificates for both RSA signature
 keys and RSA encryption keys. The intended application for the key
 may be indicated in the key usage field (see sec. 4.2.1.3).  The use
 of a single key for both signature and encryption purposes is not
 recommended, but is not forbidden.
 If the keyUsage extension is present in an end entity certificate
 which conveys an RSA public key, any combination of the following
 values may be present:  digitalSignature; nonRepudiation;
 keyEncipherment; and dataEncipherment.  If the keyUsage extension is
 present in a CA certificate which conveys an RSA public key, any
 combination of the following values may be present:
 digitalSignature; nonRepudiation; keyEncipherment; dataEncipherment;
 keyCertSign; and cRLSign.  However, this specification RECOMMENDS
 that if keyCertSign or cRLSign is present, both keyEncipherment and
 dataEncipherment should not be present.

7.3.2 Diffie-Hellman Key Exchange Key

 The Diffie-Hellman OID supported by this profile is defined by ANSI
 X9.42 [X9.42].
      dhpublicnumber OBJECT IDENTIFIER ::= { iso(1) member-body(2)
                us(840) ansi-x942(10046) number-type(2) 1 }

Housley, et. al. Standards Track [Page 61] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 The dhpublicnumber OID is intended to be used in the algorithm field
 of a value of type AlgorithmIdentifier. The parameters field of that
 type, which has the algorithm-specific syntax ANY DEFINED BY
 algorithm, have the ASN.1 type DomainParameters for this algorithm.
      DomainParameters ::= SEQUENCE {
            p       INTEGER, -- odd prime, p=jq +1
            g       INTEGER, -- generator, g
            q       INTEGER, -- factor of p-1
            j       INTEGER OPTIONAL, -- subgroup factor
            validationParms  ValidationParms OPTIONAL }
      ValidationParms ::= SEQUENCE {
            seed             BIT STRING,
            pgenCounter      INTEGER }
 The fields of type DomainParameters have the following meanings:
    p identifies the prime p defining the Galois field;
    g specifies the generator of the multiplicative subgroup of order
    g;
    q specifies the prime factor of p-1;
    j optionally specifies the value that satisfies the equation
    p=jq+1 to support the optional verification of group parameters;
    seed optionally specifies the bit string parameter used as the
    seed for the system parameter generation process; and
    pgenCounter optionally specifies the integer value output as part
    of the of the system parameter prime generation process.
 If either of the parameter generation components (pgencounter or
 seed) is provided, the other shall be present as well.
 The Diffie-Hellman public key shall be ASN.1 encoded as an INTEGER;
 this encoding shall be used as the contents (i.e., the value) of the
 subjectPublicKey component (a BIT STRING) of the subjectPublicKeyInfo
 data element.
    DHPublicKey ::= INTEGER -- public key, y = g^x mod p

Housley, et. al. Standards Track [Page 62] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 If the keyUsage extension is present in a certificate which conveys a
 DH public key, the following values may be present:  keyAgreement;
 encipherOnly; and decipherOnly.  At most one of encipherOnly and
 decipherOnly shall be asserted in keyUsage extension.

7.3.3 DSA Signature Keys

 The Digital Signature Algorithm (DSA) is also known as the Digital
 Signature Standard (DSS). The DSA OID supported by this profile is
      id-dsa ID ::= { iso(1) member-body(2) us(840) x9-57(10040)
                x9cm(4) 1 }
 The id-dsa algorithm syntax includes optional parameters.  These
 parameters are commonly referred to as p, q, and g.  When omitted,
 the parameters component shall be omitted entirely. That is, the
 AlgorithmIdentifier shall be a SEQUENCE of one component - the OBJECT
 IDENTIFIER id-dsa.
 If the DSA algorithm parameters are present in the
 subjectPublicKeyInfo AlgorithmIdentifier, the parameters are included
 using the following ASN.1 structure:
      Dss-Parms  ::=  SEQUENCE  {
          p             INTEGER,
          q             INTEGER,
          g             INTEGER  }
 If the DSA algorithm parameters are absent from the
 subjectPublicKeyInfo AlgorithmIdentifier and the CA signed the
 subject certificate using DSA, then the certificate issuer's DSA
 parameters apply to the subject's DSA key.  If the DSA algorithm
 parameters are absent from the subjectPublicKeyInfo
 AlgorithmIdentifier and the CA signed the subject certificate using a
 signature algorithm other than DSA, then the subject's DSA parameters
 are distributed by other means.  If the subjectPublicKeyInfo
 AlgorithmIdentifier field omits the parameters component and the CA
 signed the subject with a signature algorithm other than DSA, then
 clients shall reject the certificate.
 When signing, DSA algorithm generates two values.  These values are
 commonly referred to as r and s.  To easily transfer these two values
 as one signature, they are ASN.1 encoded using the following ASN.1
 structure:

Housley, et. al. Standards Track [Page 63] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

      Dss-Sig-Value  ::=  SEQUENCE  {
          r             INTEGER,
          s             INTEGER  }
 The encoded signature is conveyed as the value of the BIT STRING
 signature in a Certificate or CertificateList.
 The DSA public key shall be ASN.1 DER encoded as an INTEGER; this
 encoding shall be used as the contents (i.e., the value) of the
 subjectPublicKey component (a BIT STRING) of the SubjectPublicKeyInfo
 data element.
      DSAPublicKey ::= INTEGER -- public key, Y
 If the keyUsage extension is present in an end entity certificate
 which conveys a DSA public key, any combination of the following
 values may be present:  digitalSignature; and nonRepudiation.
 If the keyUsage extension is present in an CA certificate which
 conveys a DSA public key, any combination of the following values may
 be present:  digitalSignature; nonRepudiation; keyCertSign; and
 cRLSign.

8 References

 [FIPS 180-1]  Federal Information Processing Standards Publication
               (FIPS PUB) 180-1, Secure Hash Standard, 17 April 1995.
               [Supersedes FIPS PUB 180 dated 11 May 1993.]
 [FIPS 186]    Federal Information Processing Standards Publication
               (FIPS PUB) 186, Digital Signature Standard, 18 May
               1994.
 [RC95]        Rogier, N. and Chauvaud, P., "The compression function
               of MD2 is not collision free," Presented at Selected
               Areas in Cryptography '95, May 1995.
 [RFC 791]     Postel, J., "Internet Protocol", STD 5, RFC 791,
               September 1981.
 [RFC 822]     Crocker, D., "Standard for the format of ARPA Internet
               text messages", STD 11, RFC 822, August 1982.
 [RFC 1034]    Mockapetris, P., "Domain names - concepts and
               facilities", STD 13, RFC 1034, November 1987.
 [RFC 1319]    Kaliski, B., "The MD2 Message-Digest Algorithm," RFC
               1319, April 1992.

Housley, et. al. Standards Track [Page 64] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 [RFC 1321]    Rivest, R., "The MD5 Message-Digest Algorithm," RFC
               1321, April 1992.
 [RFC 1422]    Kent, S.,  "Privacy Enhancement for Internet Electronic
               Mail: Part II: Certificate-Based Key Management," RFC
               1422, February 1993.
 [RFC 1423]    Balenson, D., "Privacy Enhancement for Internet
               Electronic Mail: Part III: Algorithms, Modes, and
               Identifiers," RFC 1423, February 1993.
 [RFC 1519]    Fuller, V., Li, T., Yu, J. and K. Varadhan. "Classless
               Inter-Domain Routing (CIDR): an Address Assignment and
               Aggregation Strategy", RFC 1519, September 1993.
 [RFC 1738]    Berners-Lee, T., Masinter L., and M. McCahill.
               "Uniform Resource Locators (URL)", RFC 1738, December
               1994.
 [RFC 1778]    Howes, T., Kille S., Yeong, W. and C. Robbins. "The
               String Representation of Standard Attribute Syntaxes,"
               RFC 1778, March 1995.
 [RFC 1883]    Deering, S. and R. Hinden. "Internet Protocol, Version
               6 (IPv6) Specification", RFC 1883, December 1995.
 [RFC 2119]    Bradner, S., "Key words for use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC 2247]    Kille, S., Wahl, M., Grimstad, A., Huber, R. and S.
               Sataluri. "Using Domains in LDAP/X.500 Distinguished
               Names", RFC 2247, January 1998.
 [RFC 2277]    Alvestrand, H., "IETF Policy on Character Sets and
               Languages", RFC 2277, January 1998.
 [RFC 2279]    Yergeau, F., "UTF-8, a transformation format of ISO
               10646", RFC 2279, January 1998.
 [RFC 2313]    Kaliski, B., "PKCS #1: RSA Encryption Version 1.5", RFC
               2313, March 1998.
 [SDN.701]     SDN.701, "Message Security Protocol 4.0", Revision A
               1997-02-06.
 [X.208]       CCITT Recommendation X.208: Specification of Abstract
               Syntax Notation One (ASN.1), 1988.

Housley, et. al. Standards Track [Page 65] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 [X.501]       ITU-T Recommendation X.501: Information Technology -
               Open Systems Interconnection - The Directory: Models,
               1993.
 [X.509]       ITU-T Recommendation X.509 (1997 E): Information
               Technology - Open Systems Interconnection - The
               Directory: Authentication Framework, June 1997.
 [X.520]       ITU-T Recommendation X.520: Information Technology -
               Open Systems Interconnection - The Directory: Selected
               Attribute Types, 1993.
 [X9.42]       ANSI X9.42-199x, Public Key Cryptography for The
               Financial Services Industry: Agreement of Symmetric
               Algorithm Keys Using Diffie-Hellman (Working Draft),
               December 1997.
 [X9.55]       ANSI X9.55-1995, Public Key Cryptography For The
               Financial Services Industry: Extensions To Public Key
               Certificates And Certificate Revocation Lists, 8
               December, 1995.
 [X9.57]        ANSI X9.57-199x, Public Key Cryptography For The
               Financial Services Industry: Certificate Management
               (Working Draft), 21 June, 1996.

9 Intellectual Property Rights

 The IETF has been notified of intellectual property rights claimed in
 regard to some or all of the specification contained in this
 document.  For more information consult the online list of claimed
 rights.
 The IETF takes no position regarding the validity or scope of any
 intellectual property or other rights that might be claimed to
 pertain to the implementation or use of the technology described in
 this document or the extent to which any license under such rights
 might or might not be available; neither does it represent that it
 has made any effort to identify any such rights. Information on the
 IETF's procedures with respect to rights in standards-track and
 standards-related documentation can be found in BCP-11. Copies of
 claims of rights made available for publication and any assurances of
 licenses to be made available, or the result of an attempt made to

Housley, et. al. Standards Track [Page 66] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 obtain a general license or permission for the use of such
 proprietary rights by implementors or users of this specification can
 be obtained from the IETF Secretariat.

10 Security Considerations

 The majority of this specification is devoted to the format and
 content of certificates and CRLs.  Since certificates and CRLs are
 digitally signed, no additional integrity service is necessary.
 Neither certificates nor CRLs need be kept secret, and unrestricted
 and anonymous access to certificates and CRLs has no security
 implications.
 However, security factors outside the scope of this specification
 will affect the assurance provided to certificate users.  This
 section highlights critical issues that should be considered by
 implementors, administrators, and users.
 The procedures performed by CAs and RAs to validate the binding of
 the subject's identity of their public key greatly affect the
 assurance that should be placed in the certificate.  Relying parties
 may wish to review the CA's certificate practice statement.  This may
 be particularly important when issuing certificates to other CAs.
 The use of a single key pair for both signature and other purposes is
 strongly discouraged. Use of separate key pairs for signature and key
 management provides several benefits to the users. The ramifications
 associated with loss or disclosure of a signature key are different
 from loss or disclosure of a key management key. Using separate key
 pairs permits a balanced and flexible response.  Similarly, different
 validity periods or key lengths for each key pair may be appropriate
 in some application environments. Unfortunately, some legacy
 applications (e.g., SSL) use a single key pair for signature and key
 management.
 The protection afforded private keys is a critical factor in
 maintaining security.  On a small scale, failure of users to protect
 their private keys will permit an attacker to masquerade as them, or
 decrypt their personal information. On a larger scale, compromise of
 a CA's private signing key may have a catastrophic effect.  If an
 attacker obtains the private key unnoticed, the attacker may issue
 bogus certificates and CRLs.  Existence of bogus certificates and
 CRLs will undermine confidence in the system. If the compromise is
 detected, all certificates issued to the CA shall be revoked,
 preventing services between its users and users of other CAs.
 Rebuilding after such a compromise will be problematic, so CAs are
 advised to implement a combination of strong technical measures
 (e.g., tamper-resistant cryptographic modules) and appropriate

Housley, et. al. Standards Track [Page 67] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 management procedures (e.g., separation of duties) to avoid such an
 incident.
 Loss of a CA's private signing key may also be problematic.  The CA
 would not be able to produce CRLs or perform normal key rollover.
 CAs are advised to maintain secure backup for signing keys.  The
 security of the key backup procedures is a critical factor in
 avoiding key compromise.
 The availability and freshness of revocation information will affect
 the degree of assurance that should be placed in a certificate.
 While certificates expire naturally, events may occur during its
 natural lifetime which negate the binding between the subject and
 public key.  If revocation information is untimely or unavailable,
 the assurance associated with the binding is clearly reduced.
 Similarly, implementations of the Path Validation mechanism described
 in section 6 that omit revocation checking provide less assurance
 than those that support it.
 The path validation algorithm depends on the certain knowledge of the
 public keys (and other information) about one or more trusted CAs.
 The decision to trust a CA is an important decision as it ultimately
 determines the trust afforded a certificate. The authenticated
 distribution of trusted CA public keys (usually in the form of a
 "self-signed" certificate) is a security critical out of band process
 that is beyond the scope of this specification.
 In addition, where a key compromise or CA failure occurs for a
 trusted CA, the user will need to modify the information provided to
 the path validation routine.  Selection of too many trusted CAs will
 make the trusted CA information difficult to maintain.  On the other
 hand, selection of only one trusted CA may limit users to a closed
 community of users until a global PKI emerges.
 The quality of implementations that process certificates may also
 affect the degree of assurance provided.  The path validation
 algorithm described in section 6 relies upon the integrity of the
 trusted CA information, and especially the integrity of the public
 keys associated with the trusted CAs.  By substituting public keys
 for which an attacker has the private key, an attacker could trick
 the user into accepting false certificates.
 The binding between a key and certificate subject cannot be stronger
 than the cryptographic module implementation and algorithms used to
 generate the signature.  Short key lengths or weak hash algorithms
 will limit the utility of a certificate.  CAs are encouraged to note
 advances in cryptology so they can employ strong cryptographic
 techniques.  In addition, CAs should decline to issue certificates to

Housley, et. al. Standards Track [Page 68] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 CAs or end entities that generate weak signatures.
 Inconsistent application of name comparison rules may result in
 acceptance of invalid X.509 certification paths, or rejection of
 valid ones.  The X.500 series of specifications defines rules for
 comparing distinguished names require comparison of strings without
 regard to case, character set, multi-character white space substring,
 or leading and trailing white space.  This specification relaxes
 these requirements, requiring support for binary comparison at a
 minimum.
 CAs shall encode the distinguished name in the subject field of a CA
 certificate identically to the distinguished name in the issuer field
 in certificates issued by the latter CA.  If CAs use different
 encodings, implementations of this specification may fail to
 recognize name chains for paths that include this certificate.  As a
 consequence, valid paths could be rejected.
 In addition, name constraints for distinguished names shall be stated
 identically to the encoding used in the subject field or
 subjectAltName extension.  If not, (1) name constraints stated as
 excludedSubTrees will not match and invalid paths will be accepted
 and (2) name constraints expressed as permittedSubtrees will not
 match and valid paths will be rejected.  To avoid acceptance of
 invalid paths, CAs should state name constraints for distinguished
 names as permittedSubtrees where ever possible.

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Appendix A. Psuedo-ASN.1 Structures and OIDs

 This section describes data objects used by conforming PKI components
 in an "ASN.1-like" syntax.  This syntax is a hybrid of the 1988 and
 1993 ASN.1 syntaxes.  The 1988 ASN.1 syntax is augmented with 1993
 UNIVERSAL Types UniversalString, BMPString and UTF8String.
 The ASN.1 syntax does not permit the inclusion of type statements in
 the ASN.1 module, and the 1993 ASN.1 standard does not permit use of
 the new UNIVERSAL types in modules using the 1988 syntax.  As a
 result, this module does not conform to either version of the ASN.1
 standard.
 This appendix may be converted into 1988 ASN.1 by replacing the
 defintions for the UNIVERSAL Types with the 1988 catch-all "ANY".

A.1 Explicitly Tagged Module, 1988 Syntax

PKIX1Explicit88 {iso(1) identified-organization(3) dod(6) internet(1)

security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-explicit-88(1)}

DEFINITIONS EXPLICIT TAGS ::=

BEGIN

– EXPORTS ALL –

– IMPORTS NONE –

– UNIVERSAL Types defined in '93 and '98 ASN.1 – but required by this specification

UniversalString ::= [UNIVERSAL 28] IMPLICIT OCTET STRING

  1. - UniversalString is defined in ASN.1:1993

BMPString ::= [UNIVERSAL 30] IMPLICIT OCTET STRING

  1. - BMPString is the subtype of UniversalString and models
  2. - the Basic Multilingual Plane of ISO/IEC/ITU 10646-1

UTF8String ::= [UNIVERSAL 12] IMPLICIT OCTET STRING

  1. - The content of this type conforms to RFC 2279.

– – PKIX specific OIDs

id-pkix OBJECT IDENTIFIER ::=

       { iso(1) identified-organization(3) dod(6) internet(1)

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                  security(5) mechanisms(5) pkix(7) }

– PKIX arcs

id-pe OBJECT IDENTIFIER ::= { id-pkix 1 }

  1. - arc for private certificate extensions

id-qt OBJECT IDENTIFIER ::= { id-pkix 2 }

  1. - arc for policy qualifier types

id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }

  1. - arc for extended key purpose OIDS

id-ad OBJECT IDENTIFIER ::= { id-pkix 48 }

  1. - arc for access descriptors

– policyQualifierIds for Internet policy qualifiers

id-qt-cps OBJECT IDENTIFIER ::= { id-qt 1 }

  1. - OID for CPS qualifier

id-qt-unotice OBJECT IDENTIFIER ::= { id-qt 2 }

  1. - OID for user notice qualifier

– access descriptor definitions

id-ad-ocsp OBJECT IDENTIFIER ::= { id-ad 1 } id-ad-caIssuers OBJECT IDENTIFIER ::= { id-ad 2 }

– attribute data types –

Attribute ::= SEQUENCE {

      type            AttributeType,
      values  SET OF AttributeValue
              -- at least one value is required -- }

AttributeType ::= OBJECT IDENTIFIER

AttributeValue ::= ANY

AttributeTypeAndValue ::= SEQUENCE {

      type    AttributeType,
      value   AttributeValue }

– suggested naming attributes: Definition of the following – information object set may be augmented to meet local – requirements. Note that deleting members of the set may – prevent interoperability with conforming implementations. – presented in pairs: the AttributeType followed by the – type definition for the corresponding AttributeValue

–Arc for standard naming attributes id-at OBJECT IDENTIFIER ::= {joint-iso-ccitt(2) ds(5) 4}

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– Attributes of type NameDirectoryString id-at-name AttributeType ::= {id-at 41} id-at-surname AttributeType ::= {id-at 4} id-at-givenName AttributeType ::= {id-at 42} id-at-initials AttributeType ::= {id-at 43} id-at-generationQualifier AttributeType ::= {id-at 44}

X520name ::= CHOICE {

    teletexString         TeletexString (SIZE (1..ub-name)),
    printableString       PrintableString (SIZE (1..ub-name)),
    universalString       UniversalString (SIZE (1..ub-name)),
    utf8String            UTF8String (SIZE (1..ub-name)),
    bmpString             BMPString (SIZE(1..ub-name))   }

id-at-commonName AttributeType ::= {id-at 3}

X520CommonName ::= CHOICE {

    teletexString         TeletexString (SIZE (1..ub-common-name)),
    printableString       PrintableString (SIZE (1..ub-common-name)),
    universalString       UniversalString (SIZE (1..ub-common-name)),
    utf8String            UTF8String (SIZE (1..ub-common-name)),
    bmpString             BMPString (SIZE(1..ub-common-name))   }

id-at-localityName AttributeType ::= {id-at 7}

X520LocalityName ::= CHOICE {

    teletexString       TeletexString (SIZE (1..ub-locality-name)),
    printableString     PrintableString (SIZE (1..ub-locality-name)),
    universalString     UniversalString (SIZE (1..ub-locality-name)),
    utf8String          UTF8String (SIZE (1..ub-locality-name)),
    bmpString           BMPString (SIZE(1..ub-locality-name))   }

id-at-stateOrProvinceName AttributeType ::= {id-at 8}

X520StateOrProvinceName ::= CHOICE {

    teletexString       TeletexString (SIZE (1..ub-state-name)),
    printableString     PrintableString (SIZE (1..ub-state-name)),
    universalString     UniversalString (SIZE (1..ub-state-name)),
    utf8String          UTF8String (SIZE (1..ub-state-name)),
    bmpString           BMPString (SIZE(1..ub-state-name))   }

Housley, et. al. Standards Track [Page 72] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

id-at-organizationName AttributeType ::= {id-at 10}

X520OrganizationName ::= CHOICE {

teletexString     TeletexString (SIZE (1..ub-organization-name)),
printableString   PrintableString (SIZE (1..ub-organization-name)),
universalString   UniversalString (SIZE (1..ub-organization-name)),
utf8String        UTF8String (SIZE (1..ub-organization-name)),
bmpString         BMPString (SIZE(1..ub-organization-name))   }

id-at-organizationalUnitName AttributeType ::= {id-at 11}

X520OrganizationalUnitName ::= CHOICE { teletexString TeletexString (SIZE (1..ub-organizational-unit-name)), printableString PrintableString

                    (SIZE (1..ub-organizational-unit-name)),

universalString UniversalString

                    (SIZE (1..ub-organizational-unit-name)),

utf8String UTF8String (SIZE (1..ub-organizational-unit-name)), bmpString BMPString (SIZE(1..ub-organizational-unit-name)) }

id-at-title AttributeType ::= {id-at 12}

X520Title ::= CHOICE {

    teletexString         TeletexString (SIZE (1..ub-title)),
    printableString       PrintableString (SIZE (1..ub-title)),
    universalString       UniversalString (SIZE (1..ub-title)),
    utf8String            UTF8String (SIZE (1..ub-title)),
    bmpString             BMPString (SIZE(1..ub-title))   }

id-at-dnQualifier AttributeType ::= {id-at 46} X520dnQualifier ::= PrintableString

id-at-countryName AttributeType ::= {id-at 6} X520countryName ::= PrintableString (SIZE (2)) – IS 3166 codes

– Legacy attributes

pkcs-9 OBJECT IDENTIFIER ::=

     { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 9 }

emailAddress AttributeType ::= { pkcs-9 1 }

Housley, et. al. Standards Track [Page 73] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

Pkcs9email ::= IA5String (SIZE (1..ub-emailaddress-length))

– naming data types –

Name ::= CHOICE { – only one possibility for now –

                               rdnSequence  RDNSequence }

RDNSequence ::= SEQUENCE OF RelativeDistinguishedName

DistinguishedName ::= RDNSequence

RelativeDistinguishedName ::=

                  SET SIZE (1 .. MAX) OF AttributeTypeAndValue

– Directory string type –

DirectoryString ::= CHOICE {

    teletexString             TeletexString (SIZE (1..MAX)),
    printableString           PrintableString (SIZE (1..MAX)),
    universalString           UniversalString (SIZE (1..MAX)),
    utf8String              UTF8String (SIZE (1..MAX)),
    bmpString               BMPString (SIZE(1..MAX))   }

– certificate and CRL specific structures begin here

Certificate ::= SEQUENCE {

   tbsCertificate       TBSCertificate,
   signatureAlgorithm   AlgorithmIdentifier,
   signature            BIT STRING  }

TBSCertificate ::= SEQUENCE {

   version         [0]  Version DEFAULT v1,
   serialNumber         CertificateSerialNumber,
   signature            AlgorithmIdentifier,
   issuer               Name,
   validity             Validity,
   subject              Name,
   subjectPublicKeyInfo SubjectPublicKeyInfo,
   issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
                        -- If present, version shall be v2 or v3
   subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
                        -- If present, version shall be v2 or v3
   extensions      [3]  Extensions OPTIONAL
                        -- If present, version shall be v3 --  }

Version ::= INTEGER { v1(0), v2(1), v3(2) }

CertificateSerialNumber ::= INTEGER

Housley, et. al. Standards Track [Page 74] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

Validity ::= SEQUENCE {

   notBefore      Time,
   notAfter       Time }

Time ::= CHOICE {

   utcTime        UTCTime,
   generalTime    GeneralizedTime }

UniqueIdentifier ::= BIT STRING

SubjectPublicKeyInfo ::= SEQUENCE {

   algorithm            AlgorithmIdentifier,
   subjectPublicKey     BIT STRING  }

Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension

Extension ::= SEQUENCE {

   extnID      OBJECT IDENTIFIER,
   critical    BOOLEAN DEFAULT FALSE,
   extnValue   OCTET STRING  }

– CRL structures

CertificateList ::= SEQUENCE {

   tbsCertList          TBSCertList,
   signatureAlgorithm   AlgorithmIdentifier,
   signature            BIT STRING  }

TBSCertList ::= SEQUENCE {

   version                 Version OPTIONAL,
                                -- if present, shall be v2
   signature               AlgorithmIdentifier,
   issuer                  Name,
   thisUpdate              Time,
   nextUpdate              Time OPTIONAL,
   revokedCertificates     SEQUENCE OF SEQUENCE  {
        userCertificate         CertificateSerialNumber,
        revocationDate          Time,
        crlEntryExtensions      Extensions OPTIONAL
                                       -- if present, shall be v2
                             }  OPTIONAL,
   crlExtensions           [0] Extensions OPTIONAL
                                       -- if present, shall be v2 -- }

– Version, Time, CertificateSerialNumber, and Extensions were – defined earlier for use in the certificate structure

AlgorithmIdentifier ::= SEQUENCE {

Housley, et. al. Standards Track [Page 75] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

   algorithm               OBJECT IDENTIFIER,
   parameters              ANY DEFINED BY algorithm OPTIONAL  }
                              -- contains a value of the type
                              -- registered for use with the
                              -- algorithm object identifier value

– Algorithm OIDs and parameter structures

pkcs-1 OBJECT IDENTIFIER ::= {

   iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }

rsaEncryption OBJECT IDENTIFIER ::= { pkcs-1 1 }

md2WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 2 }

md5WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 4 }

sha1WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 5 }

id-dsa-with-sha1 OBJECT IDENTIFIER ::= {

   iso(1) member-body(2) us(840) x9-57 (10040) x9algorithm(4) 3 }

Dss-Sig-Value ::= SEQUENCE {

   r       INTEGER,
   s       INTEGER  }

dhpublicnumber OBJECT IDENTIFIER ::= {

   iso(1) member-body(2) us(840) ansi-x942(10046) number-type(2) 1 }

DomainParameters ::= SEQUENCE {

   p       INTEGER, -- odd prime, p=jq +1
   g       INTEGER, -- generator, g
   q       INTEGER, -- factor of p-1
   j       INTEGER OPTIONAL, -- subgroup factor, j>= 2
   validationParms  ValidationParms OPTIONAL }

ValidationParms ::= SEQUENCE {

   seed             BIT STRING,
   pgenCounter      INTEGER }

id-dsa OBJECT IDENTIFIER ::= {

   iso(1) member-body(2) us(840) x9-57(10040) x9algorithm(4) 1 }

Dss-Parms ::= SEQUENCE {

   p             INTEGER,
   q             INTEGER,
   g             INTEGER  }

Housley, et. al. Standards Track [Page 76] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

– x400 address syntax starts here – OR Names

ORAddress ::= SEQUENCE {

 built-in-standard-attributes BuiltInStandardAttributes,
 built-in-domain-defined-attributes
                      BuiltInDomainDefinedAttributes OPTIONAL,
 -- see also teletex-domain-defined-attributes
 extension-attributes ExtensionAttributes OPTIONAL }

– The OR-address is semantically absent from the OR-name if the – built-in-standard-attribute sequence is empty and the – built-in-domain-defined-attributes and extension-attributes are – both omitted.

– Built-in Standard Attributes

BuiltInStandardAttributes ::= SEQUENCE {

 country-name CountryName OPTIONAL,
 administration-domain-name AdministrationDomainName OPTIONAL,
 network-address      [0] NetworkAddress OPTIONAL,
 -- see also extended-network-address
 terminal-identifier  [1] TerminalIdentifier OPTIONAL,
 private-domain-name  [2] PrivateDomainName OPTIONAL,
 organization-name    [3] OrganizationName OPTIONAL,
 -- see also teletex-organization-name
 numeric-user-identifier      [4] NumericUserIdentifier OPTIONAL,
 personal-name        [5] PersonalName OPTIONAL,
 -- see also teletex-personal-name
 organizational-unit-names    [6] OrganizationalUnitNames OPTIONAL
 -- see also teletex-organizational-unit-names -- }

CountryName ::= [APPLICATION 1] CHOICE {

 x121-dcc-code NumericString
              (SIZE (ub-country-name-numeric-length)),
 iso-3166-alpha2-code PrintableString
              (SIZE (ub-country-name-alpha-length)) }

AdministrationDomainName ::= [APPLICATION 2] CHOICE {

 numeric NumericString (SIZE (0..ub-domain-name-length)),
 printable PrintableString (SIZE (0..ub-domain-name-length)) }

NetworkAddress ::= X121Address – see also extended-network-address

X121Address ::= NumericString (SIZE (1..ub-x121-address-length))

TerminalIdentifier ::= PrintableString (SIZE (1..ub-terminal-id-length))

PrivateDomainName ::= CHOICE {

Housley, et. al. Standards Track [Page 77] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 numeric NumericString (SIZE (1..ub-domain-name-length)),
 printable PrintableString (SIZE (1..ub-domain-name-length)) }

OrganizationName ::= PrintableString

                          (SIZE (1..ub-organization-name-length))

– see also teletex-organization-name

NumericUserIdentifier ::= NumericString

                          (SIZE (1..ub-numeric-user-id-length))

PersonalName ::= SET {

 surname [0] PrintableString (SIZE (1..ub-surname-length)),
 given-name [1] PrintableString
                      (SIZE (1..ub-given-name-length)) OPTIONAL,
 initials [2] PrintableString (SIZE (1..ub-initials-length)) OPTIONAL,
 generation-qualifier [3] PrintableString
              (SIZE (1..ub-generation-qualifier-length)) OPTIONAL }

– see also teletex-personal-name

OrganizationalUnitNames ::= SEQUENCE SIZE (1..ub-organizational-units)

                                      OF OrganizationalUnitName

– see also teletex-organizational-unit-names

OrganizationalUnitName ::= PrintableString (SIZE

                      (1..ub-organizational-unit-name-length))

– Built-in Domain-defined Attributes

BuiltInDomainDefinedAttributes ::= SEQUENCE SIZE

                              (1..ub-domain-defined-attributes) OF
                              BuiltInDomainDefinedAttribute

BuiltInDomainDefinedAttribute ::= SEQUENCE {

 type PrintableString (SIZE
                      (1..ub-domain-defined-attribute-type-length)),
 value PrintableString (SIZE
                      (1..ub-domain-defined-attribute-value-length))}

– Extension Attributes

ExtensionAttributes ::= SET SIZE (1..ub-extension-attributes) OF

                      ExtensionAttribute

ExtensionAttribute ::= SEQUENCE {

 extension-attribute-type [0] INTEGER (0..ub-extension-attributes),
 extension-attribute-value [1]
                      ANY DEFINED BY extension-attribute-type }

Housley, et. al. Standards Track [Page 78] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

– Extension types and attribute values –

common-name INTEGER ::= 1

CommonName ::= PrintableString (SIZE (1..ub-common-name-length))

teletex-common-name INTEGER ::= 2

TeletexCommonName ::= TeletexString (SIZE (1..ub-common-name-length))

teletex-organization-name INTEGER ::= 3

TeletexOrganizationName ::=

              TeletexString (SIZE (1..ub-organization-name-length))

teletex-personal-name INTEGER ::= 4

TeletexPersonalName ::= SET {

 surname [0] TeletexString (SIZE (1..ub-surname-length)),
 given-name [1] TeletexString
              (SIZE (1..ub-given-name-length)) OPTIONAL,
 initials [2] TeletexString (SIZE (1..ub-initials-length)) OPTIONAL,
 generation-qualifier [3] TeletexString (SIZE
              (1..ub-generation-qualifier-length)) OPTIONAL }

teletex-organizational-unit-names INTEGER ::= 5

TeletexOrganizationalUnitNames ::= SEQUENCE SIZE

      (1..ub-organizational-units) OF TeletexOrganizationalUnitName

TeletexOrganizationalUnitName ::= TeletexString

                      (SIZE (1..ub-organizational-unit-name-length))

pds-name INTEGER ::= 7

PDSName ::= PrintableString (SIZE (1..ub-pds-name-length))

physical-delivery-country-name INTEGER ::= 8

PhysicalDeliveryCountryName ::= CHOICE {

 x121-dcc-code NumericString (SIZE (ub-country-name-numeric-length)),
 iso-3166-alpha2-code PrintableString
                      (SIZE (ub-country-name-alpha-length)) }

postal-code INTEGER ::= 9

PostalCode ::= CHOICE {

Housley, et. al. Standards Track [Page 79] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 numeric-code NumericString (SIZE (1..ub-postal-code-length)),
 printable-code PrintableString (SIZE (1..ub-postal-code-length)) }

physical-delivery-office-name INTEGER ::= 10

PhysicalDeliveryOfficeName ::= PDSParameter

physical-delivery-office-number INTEGER ::= 11

PhysicalDeliveryOfficeNumber ::= PDSParameter

extension-OR-address-components INTEGER ::= 12

ExtensionORAddressComponents ::= PDSParameter

physical-delivery-personal-name INTEGER ::= 13

PhysicalDeliveryPersonalName ::= PDSParameter

physical-delivery-organization-name INTEGER ::= 14

PhysicalDeliveryOrganizationName ::= PDSParameter

extension-physical-delivery-address-components INTEGER ::= 15

ExtensionPhysicalDeliveryAddressComponents ::= PDSParameter

unformatted-postal-address INTEGER ::= 16

UnformattedPostalAddress ::= SET {

 printable-address SEQUENCE SIZE (1..ub-pds-physical-address-lines) OF
         PrintableString (SIZE (1..ub-pds-parameter-length)) OPTIONAL,
 teletex-string TeletexString
       (SIZE (1..ub-unformatted-address-length)) OPTIONAL }

street-address INTEGER ::= 17

StreetAddress ::= PDSParameter

post-office-box-address INTEGER ::= 18

PostOfficeBoxAddress ::= PDSParameter

poste-restante-address INTEGER ::= 19

PosteRestanteAddress ::= PDSParameter

unique-postal-name INTEGER ::= 20

Housley, et. al. Standards Track [Page 80] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

UniquePostalName ::= PDSParameter

local-postal-attributes INTEGER ::= 21

LocalPostalAttributes ::= PDSParameter

PDSParameter ::= SET {

 printable-string PrintableString
              (SIZE(1..ub-pds-parameter-length)) OPTIONAL,
 teletex-string TeletexString
              (SIZE(1..ub-pds-parameter-length)) OPTIONAL }

extended-network-address INTEGER ::= 22

ExtendedNetworkAddress ::= CHOICE {

 e163-4-address SEQUENCE {
      number [0] NumericString (SIZE (1..ub-e163-4-number-length)),
      sub-address [1] NumericString
              (SIZE (1..ub-e163-4-sub-address-length)) OPTIONAL },
 psap-address [0] PresentationAddress }

PresentationAddress ::= SEQUENCE {

      pSelector       [0] EXPLICIT OCTET STRING OPTIONAL,
      sSelector       [1] EXPLICIT OCTET STRING OPTIONAL,
      tSelector       [2] EXPLICIT OCTET STRING OPTIONAL,
      nAddresses      [3] EXPLICIT SET SIZE (1..MAX) OF OCTET STRING }

terminal-type INTEGER ::= 23

TerminalType ::= INTEGER {

 telex (3),
 teletex (4),
 g3-facsimile (5),
 g4-facsimile (6),
 ia5-terminal (7),
 videotex (8) } (0..ub-integer-options)

– Extension Domain-defined Attributes

teletex-domain-defined-attributes INTEGER ::= 6

TeletexDomainDefinedAttributes ::= SEQUENCE SIZE

 (1..ub-domain-defined-attributes) OF TeletexDomainDefinedAttribute

TeletexDomainDefinedAttribute ::= SEQUENCE {

      type TeletexString
             (SIZE (1..ub-domain-defined-attribute-type-length)),
      value TeletexString

Housley, et. al. Standards Track [Page 81] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

             (SIZE (1..ub-domain-defined-attribute-value-length)) }

– specifications of Upper Bounds shall be regarded as mandatory – from Annex B of ITU-T X.411 Reference Definition of MTS Parameter – Upper Bounds

– Upper Bounds ub-name INTEGER ::= 32768 ub-common-name INTEGER ::= 64 ub-locality-name INTEGER ::= 128 ub-state-name INTEGER ::= 128 ub-organization-name INTEGER ::= 64 ub-organizational-unit-name INTEGER ::= 64 ub-title INTEGER ::= 64 ub-match INTEGER ::= 128

ub-emailaddress-length INTEGER ::= 128

ub-common-name-length INTEGER ::= 64 ub-country-name-alpha-length INTEGER ::= 2 ub-country-name-numeric-length INTEGER ::= 3 ub-domain-defined-attributes INTEGER ::= 4 ub-domain-defined-attribute-type-length INTEGER ::= 8 ub-domain-defined-attribute-value-length INTEGER ::= 128 ub-domain-name-length INTEGER ::= 16 ub-extension-attributes INTEGER ::= 256 ub-e163-4-number-length INTEGER ::= 15 ub-e163-4-sub-address-length INTEGER ::= 40 ub-generation-qualifier-length INTEGER ::= 3 ub-given-name-length INTEGER ::= 16 ub-initials-length INTEGER ::= 5 ub-integer-options INTEGER ::= 256 ub-numeric-user-id-length INTEGER ::= 32 ub-organization-name-length INTEGER ::= 64 ub-organizational-unit-name-length INTEGER ::= 32 ub-organizational-units INTEGER ::= 4 ub-pds-name-length INTEGER ::= 16 ub-pds-parameter-length INTEGER ::= 30 ub-pds-physical-address-lines INTEGER ::= 6 ub-postal-code-length INTEGER ::= 16 ub-surname-length INTEGER ::= 40 ub-terminal-id-length INTEGER ::= 24 ub-unformatted-address-length INTEGER ::= 180 ub-x121-address-length INTEGER ::= 16

– Note - upper bounds on string types, such as TeletexString, are – measured in characters. Excepting PrintableString or IA5String, a – significantly greater number of octets will be required to hold

Housley, et. al. Standards Track [Page 82] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

– such a value. As a minimum, 16 octets, or twice the specified upper – bound, whichever is the larger, should be allowed for TeletexString. – For UTF8String or UniversalString at least four times the upper – bound should be allowed.

END

Housley, et. al. Standards Track [Page 83] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

A.2 Implicitly Tagged Module, 1988 Syntax

PKIX1Implicit88 {iso(1) identified-organization(3) dod(6) internet(1)

security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-implicit-88(2)}

DEFINITIONS IMPLICIT TAGS ::=

BEGIN

– EXPORTS ALL –

IMPORTS

      id-pkix, id-pe, id-qt, id-kp, id-qt-unotice, id-qt-cps,
          id-ad, id-ad-ocsp, id-ad-caIssuers,
          -- delete following line if "new" types are supported --
          BMPString, UniversalString, UTF8String, -- end "new" types
              ORAddress, Name, RelativeDistinguishedName,
              CertificateSerialNumber,
              CertificateList, AlgorithmIdentifier, ub-name,
              Attribute, DirectoryString
              FROM PKIX1Explicit88 {iso(1) identified-organization(3)
              dod(6) internet(1) security(5) mechanisms(5) pkix(7)
              id-mod(0) id-pkix1-explicit(1)};

– ISO arc for standard certificate and CRL extensions

id-ce OBJECT IDENTIFIER ::= {joint-iso-ccitt(2) ds(5) 29}

– authority key identifier OID and syntax

id-ce-authorityKeyIdentifier OBJECT IDENTIFIER ::= { id-ce 35 }

AuthorityKeyIdentifier ::= SEQUENCE {

    keyIdentifier             [0] KeyIdentifier            OPTIONAL,
    authorityCertIssuer       [1] GeneralNames             OPTIONAL,
    authorityCertSerialNumber [2] CertificateSerialNumber  OPTIONAL }
  -- authorityCertIssuer and authorityCertSerialNumber shall both
  -- be present or both be absent

KeyIdentifier ::= OCTET STRING

– subject key identifier OID and syntax

id-ce-subjectKeyIdentifier OBJECT IDENTIFIER ::= { id-ce 14 }

SubjectKeyIdentifier ::= KeyIdentifier

Housley, et. al. Standards Track [Page 84] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

– key usage extension OID and syntax

id-ce-keyUsage OBJECT IDENTIFIER ::= { id-ce 15 }

KeyUsage ::= BIT STRING {

   digitalSignature        (0),
   nonRepudiation          (1),
   keyEncipherment         (2),
   dataEncipherment        (3),
   keyAgreement            (4),
   keyCertSign             (5),
   cRLSign                 (6),
   encipherOnly            (7),
   decipherOnly            (8) }

– private key usage period extension OID and syntax

id-ce-privateKeyUsagePeriod OBJECT IDENTIFIER ::= { id-ce 16 }

PrivateKeyUsagePeriod ::= SEQUENCE {

   notBefore       [0]     GeneralizedTime OPTIONAL,
   notAfter        [1]     GeneralizedTime OPTIONAL }
   -- either notBefore or notAfter shall be present

– certificate policies extension OID and syntax

id-ce-certificatePolicies OBJECT IDENTIFIER ::= { id-ce 32 }

CertificatePolicies ::= SEQUENCE SIZE (1..MAX) OF PolicyInformation

PolicyInformation ::= SEQUENCE {

   policyIdentifier   CertPolicyId,
   policyQualifiers   SEQUENCE SIZE (1..MAX) OF
           PolicyQualifierInfo OPTIONAL }

CertPolicyId ::= OBJECT IDENTIFIER

PolicyQualifierInfo ::= SEQUENCE {

     policyQualifierId  PolicyQualifierId,
     qualifier        ANY DEFINED BY policyQualifierId }

– Implementations that recognize additional policy qualifiers shall – augment the following definition for PolicyQualifierId

PolicyQualifierId ::=

  OBJECT IDENTIFIER ( id-qt-cps | id-qt-unotice )

– CPS pointer qualifier

Housley, et. al. Standards Track [Page 85] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

CPSuri ::= IA5String

– user notice qualifier

UserNotice ::= SEQUENCE {

   noticeRef        NoticeReference OPTIONAL,
   explicitText     DisplayText OPTIONAL}

NoticeReference ::= SEQUENCE {

   organization     DisplayText,
   noticeNumbers    SEQUENCE OF INTEGER }

DisplayText ::= CHOICE {

   visibleString    VisibleString  (SIZE (1..200)),
   bmpString        BMPString      (SIZE (1..200)),
   utf8String       UTF8String     (SIZE (1..200)) }

– policy mapping extension OID and syntax

id-ce-policyMappings OBJECT IDENTIFIER ::= { id-ce 33 }

PolicyMappings ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {

   issuerDomainPolicy      CertPolicyId,
   subjectDomainPolicy     CertPolicyId }

– subject alternative name extension OID and syntax

id-ce-subjectAltName OBJECT IDENTIFIER ::= { id-ce 17 }

SubjectAltName ::= GeneralNames

GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName

GeneralName ::= CHOICE {

   otherName                       [0]     AnotherName,
   rfc822Name                      [1]     IA5String,
   dNSName                         [2]     IA5String,
   x400Address                     [3]     ORAddress,
   directoryName                   [4]     Name,
   ediPartyName                    [5]     EDIPartyName,
   uniformResourceIdentifier       [6]     IA5String,
   iPAddress                       [7]     OCTET STRING,
   registeredID                    [8]     OBJECT IDENTIFIER }

– AnotherName replaces OTHER-NAME ::= TYPE-IDENTIFIER, as – TYPE-IDENTIFIER is not supported in the '88 ASN.1 syntax

AnotherName ::= SEQUENCE {

Housley, et. al. Standards Track [Page 86] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

   type-id    OBJECT IDENTIFIER,
   value      [0] EXPLICIT ANY DEFINED BY type-id }

EDIPartyName ::= SEQUENCE {

   nameAssigner            [0]     DirectoryString OPTIONAL,
   partyName               [1]     DirectoryString }

– issuer alternative name extension OID and syntax

id-ce-issuerAltName OBJECT IDENTIFIER ::= { id-ce 18 }

IssuerAltName ::= GeneralNames

id-ce-subjectDirectoryAttributes OBJECT IDENTIFIER ::= { id-ce 9 }

SubjectDirectoryAttributes ::= SEQUENCE SIZE (1..MAX) OF Attribute

– basic constraints extension OID and syntax

id-ce-basicConstraints OBJECT IDENTIFIER ::= { id-ce 19 }

BasicConstraints ::= SEQUENCE {

   cA                      BOOLEAN DEFAULT FALSE,
   pathLenConstraint       INTEGER (0..MAX) OPTIONAL }

– name constraints extension OID and syntax

id-ce-nameConstraints OBJECT IDENTIFIER ::= { id-ce 30 }

NameConstraints ::= SEQUENCE {

   permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
   excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }

GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree

GeneralSubtree ::= SEQUENCE {

   base                    GeneralName,
   minimum         [0]     BaseDistance DEFAULT 0,
   maximum         [1]     BaseDistance OPTIONAL }

BaseDistance ::= INTEGER (0..MAX)

– policy constraints extension OID and syntax

id-ce-policyConstraints OBJECT IDENTIFIER ::= { id-ce 36 }

PolicyConstraints ::= SEQUENCE {

   requireExplicitPolicy           [0] SkipCerts OPTIONAL,

Housley, et. al. Standards Track [Page 87] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

   inhibitPolicyMapping            [1] SkipCerts OPTIONAL }

SkipCerts ::= INTEGER (0..MAX)

– CRL distribution points extension OID and syntax

id-ce-cRLDistributionPoints OBJECT IDENTIFIER ::= {id-ce 31}

CRLDistPointsSyntax ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint

DistributionPoint ::= SEQUENCE {

   distributionPoint       [0]     DistributionPointName OPTIONAL,
   reasons                 [1]     ReasonFlags OPTIONAL,
   cRLIssuer               [2]     GeneralNames OPTIONAL }

DistributionPointName ::= CHOICE {

   fullName                [0]     GeneralNames,
   nameRelativeToCRLIssuer [1]     RelativeDistinguishedName }

ReasonFlags ::= BIT STRING {

   unused                  (0),
   keyCompromise           (1),
   cACompromise            (2),
   affiliationChanged      (3),
   superseded              (4),
   cessationOfOperation    (5),
   certificateHold         (6) }

– extended key usage extension OID and syntax

id-ce-extKeyUsage OBJECT IDENTIFIER ::= {id-ce 37}

ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId

KeyPurposeId ::= OBJECT IDENTIFIER

– extended key purpose OIDs id-kp-serverAuth OBJECT IDENTIFIER ::= { id-kp 1 } id-kp-clientAuth OBJECT IDENTIFIER ::= { id-kp 2 } id-kp-codeSigning OBJECT IDENTIFIER ::= { id-kp 3 } id-kp-emailProtection OBJECT IDENTIFIER ::= { id-kp 4 } id-kp-ipsecEndSystem OBJECT IDENTIFIER ::= { id-kp 5 } id-kp-ipsecTunnel OBJECT IDENTIFIER ::= { id-kp 6 } id-kp-ipsecUser OBJECT IDENTIFIER ::= { id-kp 7 } id-kp-timeStamping OBJECT IDENTIFIER ::= { id-kp 8 }

– authority info access

Housley, et. al. Standards Track [Page 88] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

id-pe-authorityInfoAccess OBJECT IDENTIFIER ::= { id-pe 1 }

AuthorityInfoAccessSyntax ::=

      SEQUENCE SIZE (1..MAX) OF AccessDescription

AccessDescription ::= SEQUENCE {

      accessMethod          OBJECT IDENTIFIER,
      accessLocation        GeneralName  }

– CRL number extension OID and syntax

id-ce-cRLNumber OBJECT IDENTIFIER ::= { id-ce 20 }

CRLNumber ::= INTEGER (0..MAX)

– issuing distribution point extension OID and syntax

id-ce-issuingDistributionPoint OBJECT IDENTIFIER ::= { id-ce 28 }

IssuingDistributionPoint ::= SEQUENCE {

   distributionPoint       [0] DistributionPointName OPTIONAL,
   onlyContainsUserCerts   [1] BOOLEAN DEFAULT FALSE,
   onlyContainsCACerts     [2] BOOLEAN DEFAULT FALSE,
   onlySomeReasons         [3] ReasonFlags OPTIONAL,
   indirectCRL             [4] BOOLEAN DEFAULT FALSE }

id-ce-deltaCRLIndicator OBJECT IDENTIFIER ::= { id-ce 27 }

– deltaCRLIndicator ::= BaseCRLNumber

BaseCRLNumber ::= CRLNumber

– CRL reasons extension OID and syntax

id-ce-cRLReasons OBJECT IDENTIFIER ::= { id-ce 21 }

CRLReason ::= ENUMERATED {

   unspecified             (0),
   keyCompromise           (1),
   cACompromise            (2),
   affiliationChanged      (3),
   superseded              (4),
   cessationOfOperation    (5),
   certificateHold         (6),
   removeFromCRL           (8) }

– certificate issuer CRL entry extension OID and syntax

Housley, et. al. Standards Track [Page 89] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

id-ce-certificateIssuer OBJECT IDENTIFIER ::= { id-ce 29 }

CertificateIssuer ::= GeneralNames

– hold instruction extension OID and syntax

id-ce-holdInstructionCode OBJECT IDENTIFIER ::= { id-ce 23 }

HoldInstructionCode ::= OBJECT IDENTIFIER

– ANSI x9 holdinstructions

– ANSI x9 arc holdinstruction arc holdInstruction OBJECT IDENTIFIER ::=

        {joint-iso-itu-t(2) member-body(2) us(840) x9cm(10040) 2}

– ANSI X9 holdinstructions referenced by this standard id-holdinstruction-none OBJECT IDENTIFIER ::=

              {holdInstruction 1} -- deprecated

id-holdinstruction-callissuer OBJECT IDENTIFIER ::=

              {holdInstruction 2}

id-holdinstruction-reject OBJECT IDENTIFIER ::=

              {holdInstruction 3}

– invalidity date CRL entry extension OID and syntax

id-ce-invalidityDate OBJECT IDENTIFIER ::= { id-ce 24 }

InvalidityDate ::= GeneralizedTime

END

Housley, et. al. Standards Track [Page 90] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

Appendix B. 1993 ASN.1 Structures and OIDs

B.1 Explicitly Tagged Module, 1993 Syntax

PKIX1Explicit93 {iso(1) identified-organization(3) dod(6) internet(1)

 security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-explicit-93(3)}

DEFINITIONS EXPLICIT TAGS ::=

BEGIN

– EXPORTS ALL –

IMPORTS

      authorityKeyIdentifier, subjectKeyIdentifier, keyUsage,
         extendedKeyUsage, privateKeyUsagePeriod, certificatePolicies,
         policyMappings, subjectAltName, issuerAltName,
         basicConstraints, nameConstraints, policyConstraints,
         cRLDistributionPoints, subjectDirectoryAttributes,
         cRLNumber, reasonCode, instructionCode, invalidityDate,
         issuingDistributionPoint, certificateIssuer,
         deltaCRLIndicator, authorityInfoAccess, id-ce
         FROM PKIX1Implicit93 {iso(1) identified-organization(3)
         dod(6) internet(1) security(5) mechanisms(5) pkix(7)
         id-mod(0) id-pkix1-implicit-93(4)} ;

  1. - Locally defined OIDs –

id-pkix OBJECT IDENTIFIER ::=

       { iso(1) identified-organization(3) dod(6) internet(1)
                  security(5) mechanisms(5) pkix(7) }

– PKIX arcs – arc for private certificate extensions id-pe OBJECT IDENTIFIER ::= { id-pkix 1 } – arc for policy qualifier types id-qt OBJECT IDENTIFIER ::= { id-pkix 2 } – arc for extended key purpose OIDS id-kp OBJECT IDENTIFIER ::= { id-pkix 3 } – arc for access descriptors id-ad OBJECT IDENTIFIER ::= { id-pkix 48 }

– policyQualifierIds for Internet policy qualifiers id-qt-cps OBJECT IDENTIFIER ::= { id-qt 1 }

  1. - OID for CPS qualifier

Housley, et. al. Standards Track [Page 91] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

id-qt-unotice OBJECT IDENTIFIER ::= { id-qt 2 }

  1. - OID for user notice qualifier

– based on excerpts from AuthenticationFramework – {joint-iso-ccitt ds(5) modules(1) authenticationFramework(7) 2}

  1. - Public Key Certificate –

Certificate ::= SIGNED { SEQUENCE {

 version                 [0]   Version DEFAULT v1,
 serialNumber                  CertificateSerialNumber,
 signature                     AlgorithmIdentifier,
 issuer                        Name,
 validity                      Validity,
 subject                       Name,
 subjectPublicKeyInfo          SubjectPublicKeyInfo,
 issuerUniqueIdentifier  [1]   IMPLICIT UniqueIdentifier OPTIONAL,
                            ---if present, version shall be v2 or v3--
 subjectUniqueIdentifier [2]   IMPLICIT UniqueIdentifier OPTIONAL,
                            ---if present, version shall be v2 or v3--
 extensions              [3]   Extensions OPTIONAL
                            --if present, version shall be v3--}  }

UniqueIdentifier ::= BIT STRING

Version ::= INTEGER { v1(0), v2(1), v3(2) }

CertificateSerialNumber ::= INTEGER

Validity ::= SEQUENCE {

 notBefore            Time,
 notAfter             Time }

Time ::= CHOICE {

      utcTime         UTCTime,
      generalTime             GeneralizedTime }

SubjectPublicKeyInfo ::= SEQUENCE{

 algorithm            AlgorithmIdentifier,
 subjectPublicKey     BIT STRING}

Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension

Extension ::= SEQUENCE {

 extnId            EXTENSION.&id ({ExtensionSet}),
 critical          BOOLEAN DEFAULT FALSE,
 extnValue         OCTET STRING }
              -- contains a DER encoding of a value of type

Housley, et. al. Standards Track [Page 92] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

  1. - &ExtnType for the
  2. - extension object identified by extnId –

– The following information object set is defined to constrain the – set of legal certificate extensions.

ExtensionSet EXTENSION ::= { authorityKeyIdentifier |

                                      subjectKeyIdentifier |
                                      keyUsage |
                                      extendedKeyUsage |
                                      privateKeyUsagePeriod |
                                      certificatePolicies |
                                      policyMappings |
                                      subjectAltName |
                                      issuerAltName |
                                      basicConstraints |
                                      nameConstraints |
                                      policyConstraints |
                                      cRLDistributionPoints |
                                      subjectDirectoryAttributes |
                                      authorityInfoAccess }

EXTENSION ::= CLASS {

 &id          OBJECT IDENTIFIER UNIQUE,
 &ExtnType }

WITH SYNTAX {

 SYNTAX               &ExtnType
 IDENTIFIED BY        &id }
  1. - Certificate Revocation List –

CertificateList ::= SIGNED { SEQUENCE {

 version                Version  OPTIONAL, -- if present, shall be v2
 signature              AlgorithmIdentifier,
 issuer                 Name,
 thisUpdate             Time,
 nextUpdate             Time OPTIONAL,
 revokedCertificates    SEQUENCE OF SEQUENCE {
 userCertificate        CertificateSerialNumber,
 revocationDate         Time,
 crlEntryExtensions     EntryExtensions OPTIONAL } OPTIONAL,
 crlExtensions          [0]   CRLExtensions OPTIONAL }}

CRLExtensions ::= SEQUENCE SIZE (1..MAX) OF CRLExtension

CRLExtension ::= SEQUENCE {

 extnId            EXTENSION.&id ({CRLExtensionSet}),
 critical          BOOLEAN DEFAULT FALSE,

Housley, et. al. Standards Track [Page 93] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

 extnValue         OCTET STRING }
              -- contains a DER encoding of a value of type
              -- &ExtnType for the
              -- extension object identified by extnId --

– The following information object set is defined to constrain the – set of legal CRL extensions.

CRLExtensionSet EXTENSION ::= { authorityKeyIdentifier |

                                      issuerAltName |
                                      cRLNumber |
                                      deltaCRLIndicator |
                                      issuingDistributionPoint }

– EXTENSION defined above for certificates

EntryExtensions ::= SEQUENCE SIZE (1..MAX) OF EntryExtension

EntryExtension ::= SEQUENCE {

 extnId            EXTENSION.&id ({EntryExtensionSet}),
 critical          BOOLEAN DEFAULT FALSE,
 extnValue         OCTET STRING }
              -- contains a DER encoding of a value of type
              -- &ExtnType for the
              -- extension object identified by extnId --

– The following information object set is defined to constrain the – set of legal CRL entry extensions.

EntryExtensionSet EXTENSION ::= { reasonCode |

                                              instructionCode |
                                              invalidityDate |
                                              certificateIssuer }
  1. - information object classes used in the defintion –
    1. - of certificates and CRLs –

– Parameterized Type SIGNED –

SIGNED { ToBeSigned } ::= SEQUENCE {
   toBeSigned  ToBeSigned,
   algorithm   AlgorithmIdentifier,
   signature   BIT STRING
}

– Definition of AlgorithmIdentifier – ISO definition was: –

Housley, et. al. Standards Track [Page 94] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

– AlgorithmIdentifier ::= SEQUENCE { – algorithm ALGORITHM.&id({SupportedAlgorithms}), – parameters ALGORITHM.&Type({SupportedAlgorithms} – { @algorithm}) OPTIONAL } – Definition of ALGORITHM – ALGORITHM ::= TYPE-IDENTIFIER

– The following PKIX definition replaces the X.509 definition –

AlgorithmIdentifier ::= SEQUENCE {

 algorithm            ALGORITHM-ID.&id({SupportedAlgorithms}),
 parameters           ALGORITHM-ID.&Type({SupportedAlgorithms}
                                         { @algorithm}) OPTIONAL }

– Definition of ALGORITHM-ID

ALGORITHM-ID ::= CLASS {

   &id    OBJECT IDENTIFIER UNIQUE,
   &Type  OPTIONAL
}
   WITH SYNTAX { OID &id [PARMS &Type] }

– The definition of SupportedAlgorithms may be modified as this – document does not specify a mandatory algorithm set. In addition, – the set is specified as extensible, since additional algorithms – may be supported

SupportedAlgorithms ALGORITHM-ID ::= { …, – extensible

                                          rsaPublicKey |
                                          rsaSHA-1  |
                                          rsaMD5 |
                                          rsaMD2 |
                                          dssPublicKey |
                                          dsaSHA-1 |
                                          dhPublicKey }

– OIDs and parameter structures for ALGORITHM-IDs used – in this specification

rsaPublicKey ALGORITHM-ID ::= { OID rsaEncryption PARMS NULL }

rsaSHA-1 ALGORITHM-ID ::= { OID sha1WithRSAEncryption PARMS NULL }

rsaMD5 ALGORITHM-ID ::= { OID md5WithRSAEncryption PARMS NULL }

rsaMD2 ALGORITHM-ID ::= { OID md2WithRSAEncryption PARMS NULL }

Housley, et. al. Standards Track [Page 95] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

dssPublicKey ALGORITHM-ID ::= { OID id-dsa PARMS Dss-Parms }

dsaSHA-1 ALGORITHM-ID ::= { OID id-dsa-with-sha1 }

dhPublicKey ALGORITHM-ID ::= {OID dhpublicnumber PARMS DomainParameters}

– algorithm identifiers and parameter structures

pkcs-1 OBJECT IDENTIFIER ::= {

   iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }

rsaEncryption OBJECT IDENTIFIER ::= { pkcs-1 1 }

md2WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 2 }

md5WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 4 }

sha1WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 5 }

id-dsa-with-sha1 OBJECT IDENTIFIER ::= {

   iso(1) member-body(2) us(840) x9-57 (10040) x9algorithm(4) 3 }

Dss-Sig-Value ::= SEQUENCE {

   r       INTEGER,
   s       INTEGER  }

dhpublicnumber OBJECT IDENTIFIER ::= {

   iso(1) member-body(2) us(840) ansi-x942(10046) number-type(2) 1 }

DomainParameters ::= SEQUENCE {

   p       INTEGER, -- odd prime, p=jq +1
   g       INTEGER, -- generator, g
   q       INTEGER, -- factor of p-1
   j       INTEGER OPTIONAL, -- subgroup factor, j>= 2
   validationParms  ValidationParms OPTIONAL }

ValidationParms ::= SEQUENCE {

   seed             BIT STRING,
   pgenCounter      INTEGER }

id-dsa OBJECT IDENTIFIER ::= {

   iso(1) member-body(2) us(840) x9-57(10040) x9algorithm(4) 1 }

Dss-Parms ::= SEQUENCE {

   p             INTEGER,
   q             INTEGER,
   g             INTEGER  }

Housley, et. al. Standards Track [Page 96] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

  1. - The ASN.1 in this section supports the Name type
  2. - and the directoryAttribute extension

– attribute data types –

Attribute ::= SEQUENCE {

      type            ATTRIBUTE.&id ({SupportedAttributes}),
      values  SET SIZE (1 .. MAX) OF ATTRIBUTE.&Type
                      ({SupportedAttributes}{@type})}

AttributeTypeAndValue ::= SEQUENCE {

      type            ATTRIBUTE.&id ({SupportedAttributes}),
      value   ATTRIBUTE.&Type ({SupportedAttributes}{@type})}

– naming data types –

Name ::= CHOICE { – only one possibility for now –

                                      rdnSequence  RDNSequence }

RDNSequence ::= SEQUENCE OF RelativeDistinguishedName

RelativeDistinguishedName ::=

              SET SIZE (1 .. MAX) OF AttributeTypeAndValue

ID ::= OBJECT IDENTIFIER

– ATTRIBUTE information object class specification – Note: This has been greatly simplified for PKIX !!

ATTRIBUTE ::= CLASS {

      &Type,
      &id                     OBJECT IDENTIFIER UNIQUE }

WITH SYNTAX {

      WITH SYNTAX &Type ID &id }

– suggested naming attributes – Definition of the following information object set may be – augmented to meet local requirements. Note that deleting – members of the set may prevent interoperability with – conforming implementations.

SupportedAttributes ATTRIBUTE ::= {

              name | commonName | surname | givenName | initials |
              generationQualifier | dnQualifier | countryName |
              localityName | stateOrProvinceName | organizationName |
                      organizationalUnitName | title | pkcs9email }

name ATTRIBUTE ::= {

Housley, et. al. Standards Track [Page 97] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

      WITH SYNTAX                     DirectoryString { ub-name }
      ID                              id-at-name }

commonName ATTRIBUTE ::= {

      WITH SYNTAX                     DirectoryString {ub-common-name}
      ID                              id-at-commonName }

surname ATTRIBUTE ::= {

      WITH SYNTAX                     DirectoryString {ub-name}
      ID                              id-at-surname }

givenName ATTRIBUTE ::= {

      WITH SYNTAX                     DirectoryString {ub-name}
      ID                              id-at-givenName }

initials ATTRIBUTE ::= {

      WITH SYNTAX                     DirectoryString {ub-name}
      ID                              id-at-initials }

generationQualifier ATTRIBUTE ::= {

      WITH SYNTAX                     DirectoryString {ub-name}
      ID                              id-at-generationQualifier}

dnQualifier ATTRIBUTE ::= {

      WITH SYNTAX                     PrintableString
      ID                              id-at-dnQualifier }

countryName ATTRIBUTE ::= {

      WITH SYNTAX                     PrintableString (SIZE (2))
                                              -- IS 3166 codes only
      ID                              id-at-countryName }

localityName ATTRIBUTE ::= {

      WITH SYNTAX             DirectoryString {ub-locality-name}
      ID                      id-at-localityName }

stateOrProvinceName ATTRIBUTE ::= {

      WITH SYNTAX             DirectoryString {ub-state-name}
      ID                      id-at-stateOrProvinceName }

organizationName ATTRIBUTE ::= {

      WITH SYNTAX             DirectoryString {ub-organization-name}
      ID                      id-at-organizationName }

organizationalUnitName ATTRIBUTE ::= {

      WITH SYNTAX  DirectoryString {ub-organizational-unit-name}
      ID                      id-at-organizationalUnitName }

Housley, et. al. Standards Track [Page 98] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

title ATTRIBUTE ::= {

      WITH SYNTAX             DirectoryString {ub-title}
      ID                      id-at-title }

– Legacy attributes

pkcs9email ATTRIBUTE ::= {

      WITH SYNTAX                     PHGString,
      ID                              emailAddress }

PHGString ::= IA5String (SIZE(1..ub-emailaddress-length))

pkcs-9 OBJECT IDENTIFIER ::=

     { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 9 }

emailAddress OBJECT IDENTIFIER ::= { pkcs-9 1 }

  1. - object identifiers for Name type and directory attribute support

– Object identifier assignments –

id-at OBJECT IDENTIFIER ::= {joint-iso-ccitt(2) ds(5) 4}

– Attributes –

id-at-commonName OBJECT IDENTIFIER ::= {id-at 3} id-at-surname OBJECT IDENTIFIER ::= {id-at 4} id-at-countryName OBJECT IDENTIFIER ::= {id-at 6} id-at-localityName OBJECT IDENTIFIER ::= {id-at 7} id-at-stateOrProvinceName OBJECT IDENTIFIER ::= {id-at 8} id-at-organizationName OBJECT IDENTIFIER ::= {id-at 10} id-at-organizationalUnitName OBJECT IDENTIFIER ::= {id-at 11} id-at-title OBJECT IDENTIFIER ::= {id-at 12} id-at-name OBJECT IDENTIFIER ::= {id-at 41} id-at-givenName OBJECT IDENTIFIER ::= {id-at 42} id-at-initials OBJECT IDENTIFIER ::= {id-at 43} id-at-generationQualifier OBJECT IDENTIFIER ::= {id-at 44} id-at-dnQualifier OBJECT IDENTIFIER ::= {id-at 46}

– Directory string type, used extensively in Name types –

DirectoryString { INTEGER:maxSize } ::= CHOICE {

      teletexString           TeletexString (SIZE (1..maxSize)),
      printableString         PrintableString (SIZE (1..maxSize)),
      universalString         UniversalString (SIZE (1..maxSize)),
      bmpString               BMPString (SIZE(1..maxSize)),
      utf8String              UTF8String (SIZE(1..maxSize))
                          }

Housley, et. al. Standards Track [Page 99] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

  1. - End of ASN.1 for Name type and directory attribute support –
  1. - The ASN.1 in this section supports X.400 style names –
  2. - for implementations that use the x400Address component –
  3. - of GeneralName. –

ORAddress ::= SEQUENCE {

 built-in-standard-attributes BuiltInStandardAttributes,
 built-in-domain-defined-attributes
                      BuiltInDomainDefinedAttributes OPTIONAL,
 -- see also teletex-domain-defined-attributes
 extension-attributes ExtensionAttributes OPTIONAL }

– The OR-address is semantically absent from the OR-name if the – built-in-standard-attribute sequence is empty and the – built-in-domain-defined-attributes and extension-attributes are – both omitted.

– Built-in Standard Attributes

BuiltInStandardAttributes ::= SEQUENCE {

 country-name CountryName OPTIONAL,
 administration-domain-name AdministrationDomainName OPTIONAL,
 network-address      [0] NetworkAddress OPTIONAL,
 -- see also extended-network-address
 terminal-identifier  [1] TerminalIdentifier OPTIONAL,
 private-domain-name  [2] PrivateDomainName OPTIONAL,
 organization-name    [3] OrganizationName OPTIONAL,
 -- see also teletex-organization-name
 numeric-user-identifier      [4] NumericUserIdentifier OPTIONAL,
 personal-name        [5] PersonalName OPTIONAL,
 -- see also teletex-personal-name
 organizational-unit-names    [6] OrganizationalUnitNames OPTIONAL
 -- see also teletex-organizational-unit-names -- }

CountryName ::= [APPLICATION 1] CHOICE {

 x121-dcc-code NumericString
              (SIZE (ub-country-name-numeric-length)),
 iso-3166-alpha2-code PrintableString
              (SIZE (ub-country-name-alpha-length)) }

AdministrationDomainName ::= [APPLICATION 2] CHOICE {

 numeric NumericString (SIZE (0..ub-domain-name-length)),
 printable PrintableString (SIZE (0..ub-domain-name-length)) }

NetworkAddress ::= X121Address – see also extended-network-address

Housley, et. al. Standards Track [Page 100] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

X121Address ::= NumericString (SIZE (1..ub-x121-address-length))

TerminalIdentifier ::= PrintableString (SIZE (1..ub-terminal-id-length))

PrivateDomainName ::= CHOICE {

 numeric NumericString (SIZE (1..ub-domain-name-length)),
 printable PrintableString (SIZE (1..ub-domain-name-length)) }

OrganizationName ::= PrintableString

                         (SIZE (1..ub-organization-name-length))

– see also teletex-organization-name

NumericUserIdentifier ::= NumericString

                           (SIZE (1..ub-numeric-user-id-length))

PersonalName ::= SET {

 surname    [0] PrintableString (SIZE (1..ub-surname-length)),
 given-name [1] PrintableString
                      (SIZE (1..ub-given-name-length)) OPTIONAL,
 initials   [2] PrintableString
                      (SIZE (1..ub-initials-length)) OPTIONAL,
 generation-qualifier [3] PrintableString
              (SIZE (1..ub-generation-qualifier-length)) OPTIONAL}

– see also teletex-personal-name

OrganizationalUnitNames ::= SEQUENCE SIZE (1..ub-organizational-units)

                                      OF OrganizationalUnitName

– see also teletex-organizational-unit-names

OrganizationalUnitName ::= PrintableString (SIZE

                      (1..ub-organizational-unit-name-length))

– Built-in Domain-defined Attributes BuiltInDomainDefinedAttributes ::= SEQUENCE SIZE

                              (1..ub-domain-defined-attributes) OF
                              BuiltInDomainDefinedAttribute

BuiltInDomainDefinedAttribute ::= SEQUENCE {

 type PrintableString (SIZE
              (1..ub-domain-defined-attribute-type-length)),
 value PrintableString (SIZE
              (1..ub-domain-defined-attribute-value-length)) }

– Extension Attributes

ExtensionAttributes ::= SET SIZE (1..ub-extension-attributes)

                                      OF ExtensionAttribute

ExtensionAttribute ::= SEQUENCE {

Housley, et. al. Standards Track [Page 101] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

      extension-attribute-type [0] EXTENSION-ATTRIBUTE.&id
                                      ({ExtensionAttributeTable}),
      extension-attribute-value [1] EXTENSION-ATTRIBUTE.&Type
           ({ExtensionAttributeTable} {@extension-attribute-type}) }

EXTENSION-ATTRIBUTE ::= CLASS {

      &id     INTEGER (0..ub-extension-attributes) UNIQUE,
      &Type }

WITH SYNTAX {&Type IDENTIFIED BY &id}

ExtensionAttributeTable EXTENSION-ATTRIBUTE ::= {

      common-name |
      teletex-common-name |
      teletex-organization-name |
      teletex-personal-name |
      teletex-organizational-unit-names |
      teletex-domain-defined-attributes |
      pds-name |
      physical-delivery-country-name |
      postal-code |
      physical-delivery-office-name |
      physical-delivery-office-number |
      extension-OR-address-components |
      physical-delivery-personal-name |
      physical-delivery-organization-name |
      extension-physical-delivery-address-components |
      unformatted-postal-address |
      street-address |
      post-office-box-address |
      poste-restante-address |
      unique-postal-name |
      local-postal-attributes |
      extended-network-address |
      terminal-type }

– Extension Standard Attributes

common-name EXTENSION-ATTRIBUTE ::= {CommonName IDENTIFIED BY 1}

CommonName ::= PrintableString (SIZE (1..ub-common-name-length))

teletex-common-name EXTENSION-ATTRIBUTE ::=

              {TeletexCommonName IDENTIFIED BY 2}

TeletexCommonName ::= TeletexString (SIZE (1..ub-common-name-length))

teletex-organization-name EXTENSION-ATTRIBUTE ::=

              {TeletexOrganizationName IDENTIFIED BY 3}

Housley, et. al. Standards Track [Page 102] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

TeletexOrganizationName ::=

              TeletexString (SIZE (1..ub-organization-name-length))

teletex-personal-name EXTENSION-ATTRIBUTE ::=

              {TeletexPersonalName IDENTIFIED BY 4}

TeletexPersonalName ::= SET {

 surname [0] TeletexString (SIZE (1..ub-surname-length)),
 given-name [1] TeletexString
              (SIZE (1..ub-given-name-length)) OPTIONAL,
 initials [2] TeletexString (SIZE (1..ub-initials-length)) OPTIONAL,
 generation-qualifier [3] TeletexString (SIZE
              (1..ub-generation-qualifier-length)) OPTIONAL }

teletex-organizational-unit-names EXTENSION-ATTRIBUTE ::=

 {TeletexOrganizationalUnitNames IDENTIFIED BY 5}

TeletexOrganizationalUnitNames ::= SEQUENCE SIZE

      (1..ub-organizational-units) OF TeletexOrganizationalUnitName

TeletexOrganizationalUnitName ::= TeletexString

                      (SIZE (1..ub-organizational-unit-name-length))

pds-name EXTENSION-ATTRIBUTE ::= {PDSName IDENTIFIED BY 7}

PDSName ::= PrintableString (SIZE (1..ub-pds-name-length))

physical-delivery-country-name EXTENSION-ATTRIBUTE ::=

 {PhysicalDeliveryCountryName IDENTIFIED BY 8}

PhysicalDeliveryCountryName ::= CHOICE {

 x121-dcc-code NumericString (SIZE (ub-country-name-numeric-length)),
 iso-3166-alpha2-code PrintableString
                      (SIZE (ub-country-name-alpha-length)) }

postal-code EXTENSION-ATTRIBUTE ::= {PostalCode IDENTIFIED BY 9}

PostalCode ::= CHOICE {

 numeric-code NumericString (SIZE (1..ub-postal-code-length)),
 printable-code PrintableString (SIZE (1..ub-postal-code-length)) }

physical-delivery-office-name EXTENSION-ATTRIBUTE ::=

                      {PhysicalDeliveryOfficeName IDENTIFIED BY 10}

PhysicalDeliveryOfficeName ::= PDSParameter

physical-delivery-office-number EXTENSION-ATTRIBUTE ::=

 {PhysicalDeliveryOfficeNumber IDENTIFIED BY 11}

Housley, et. al. Standards Track [Page 103] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

PhysicalDeliveryOfficeNumber ::= PDSParameter

extension-OR-address-components EXTENSION-ATTRIBUTE ::=

 {ExtensionORAddressComponents IDENTIFIED BY 12}

ExtensionORAddressComponents ::= PDSParameter

physical-delivery-personal-name EXTENSION-ATTRIBUTE ::=

 {PhysicalDeliveryPersonalName IDENTIFIED BY 13}

PhysicalDeliveryPersonalName ::= PDSParameter

physical-delivery-organization-name EXTENSION-ATTRIBUTE ::=

 {PhysicalDeliveryOrganizationName IDENTIFIED BY 14}

PhysicalDeliveryOrganizationName ::= PDSParameter

extension-physical-delivery-address-components EXTENSION-ATTRIBUTE ::=

 {ExtensionPhysicalDeliveryAddressComponents IDENTIFIED BY 15}

ExtensionPhysicalDeliveryAddressComponents ::= PDSParameter

unformatted-postal-address EXTENSION-ATTRIBUTE ::=

                      {UnformattedPostalAddress IDENTIFIED BY 16}

UnformattedPostalAddress ::= SET {

 printable-address SEQUENCE SIZE (1..ub-pds-physical-address-lines) OF
         PrintableString (SIZE (1..ub-pds-parameter-length)) OPTIONAL,
 teletex-string TeletexString (SIZE
                       (1..ub-unformatted-address-length)) OPTIONAL }

street-address EXTENSION-ATTRIBUTE ::=

              {StreetAddress IDENTIFIED BY 17}

StreetAddress ::= PDSParameter

post-office-box-address EXTENSION-ATTRIBUTE ::=

              {PostOfficeBoxAddress IDENTIFIED BY 18}

PostOfficeBoxAddress ::= PDSParameter

poste-restante-address EXTENSION-ATTRIBUTE ::=

              {PosteRestanteAddress IDENTIFIED BY 19}

PosteRestanteAddress ::= PDSParameter

unique-postal-name EXTENSION-ATTRIBUTE ::=

              {UniquePostalName IDENTIFIED BY 20}

Housley, et. al. Standards Track [Page 104] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

UniquePostalName ::= PDSParameter

local-postal-attributes EXTENSION-ATTRIBUTE ::=

              {LocalPostalAttributes IDENTIFIED BY 21}

LocalPostalAttributes ::= PDSParameter

PDSParameter ::= SET {

 printable-string PrintableString
          (SIZE(1..ub-pds-parameter-length)) OPTIONAL,
 teletex-string TeletexString
          (SIZE(1..ub-pds-parameter-length)) OPTIONAL }

extended-network-address EXTENSION-ATTRIBUTE ::=

              {ExtendedNetworkAddress IDENTIFIED BY 22}

ExtendedNetworkAddress ::= CHOICE {

      e163-4-address SEQUENCE {
              number [0] NumericString
                 (SIZE (1..ub-e163-4-number-length)),
              sub-address [1] NumericString
                 (SIZE (1..ub-e163-4-sub-address-length)) OPTIONAL},
      psap-address [0] PresentationAddress }

PresentationAddress ::= SEQUENCE {

      pSelector       [0] EXPLICIT OCTET STRING OPTIONAL,
      sSelector       [1] EXPLICIT OCTET STRING OPTIONAL,
      tSelector       [2] EXPLICIT OCTET STRING OPTIONAL,
      nAddresses      [3] EXPLICIT SET SIZE (1..MAX) OF OCTET STRING}

terminal-type EXTENSION-ATTRIBUTE ::= {TerminalType IDENTIFIED BY 23}

TerminalType ::= INTEGER {

 telex (3),
 teletex (4),
 g3-facsimile (5),
 g4-facsimile (6),
 ia5-terminal (7),
 videotex (8) } (0..ub-integer-options)

– Extension Domain-defined Attributes

teletex-domain-defined-attributes EXTENSION-ATTRIBUTE ::=

 {TeletexDomainDefinedAttributes IDENTIFIED BY 6}

TeletexDomainDefinedAttributes ::= SEQUENCE SIZE

 (1..ub-domain-defined-attributes) OF TeletexDomainDefinedAttribute

Housley, et. al. Standards Track [Page 105] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

TeletexDomainDefinedAttribute ::= SEQUENCE {

  type TeletexString
       (SIZE (1..ub-domain-defined-attribute-type-length)),
  value TeletexString
       (SIZE (1..ub-domain-defined-attribute-value-length)) }

– specifications of Upper Bounds – shall be regarded as mandatory – from Annex B of ITU-T X.411 – Reference Definition of MTS Parameter Upper Bounds

– Upper Bounds ub-name INTEGER ::= 32768 ub-common-name INTEGER ::= 64 ub-locality-name INTEGER ::= 128 ub-state-name INTEGER ::= 128 ub-organization-name INTEGER ::= 64 ub-organizational-unit-name INTEGER ::= 64 ub-title INTEGER ::= 64 ub-match INTEGER ::= 128

ub-emailaddress-length INTEGER ::= 128

ub-common-name-length INTEGER ::= 64 ub-country-name-alpha-length INTEGER ::= 2 ub-country-name-numeric-length INTEGER ::= 3 ub-domain-defined-attributes INTEGER ::= 4 ub-domain-defined-attribute-type-length INTEGER ::= 8 ub-domain-defined-attribute-value-length INTEGER ::= 128 ub-domain-name-length INTEGER ::= 16 ub-extension-attributes INTEGER ::= 256 ub-e163-4-number-length INTEGER ::= 15 ub-e163-4-sub-address-length INTEGER ::= 40 ub-generation-qualifier-length INTEGER ::= 3 ub-given-name-length INTEGER ::= 16 ub-initials-length INTEGER ::= 5 ub-integer-options INTEGER ::= 256 ub-numeric-user-id-length INTEGER ::= 32 ub-organization-name-length INTEGER ::= 64 ub-organizational-unit-name-length INTEGER ::= 32 ub-organizational-units INTEGER ::= 4 ub-pds-name-length INTEGER ::= 16 ub-pds-parameter-length INTEGER ::= 30 ub-pds-physical-address-lines INTEGER ::= 6 ub-postal-code-length INTEGER ::= 16 ub-surname-length INTEGER ::= 40 ub-terminal-id-length INTEGER ::= 24 ub-unformatted-address-length INTEGER ::= 180

Housley, et. al. Standards Track [Page 106] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

ub-x121-address-length INTEGER ::= 16

– Note - upper bounds on TeletexString are measured in characters. – A significantly greater number of octets will be required to hold – such a value. As a minimum, 16 octets, or twice the specified upper – bound, whichever is the larger, should be allowed.

END

Housley, et. al. Standards Track [Page 107] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

B.2 Implicitly Tagged Module, 1993 Syntax

PKIX1Implicit93 {iso(1) identified-organization(3) dod(6) internet(1)

 security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-implicit-93(4)}

DEFINITIONS IMPLICIT TAGS::=

BEGIN

–EXPORTS ALL –

IMPORTS

      id-pe, id-qt, id-kp, id-ad, id-qt-unotice,
              ORAddress, Name, RelativeDistinguishedName,
              CertificateSerialNumber, CertificateList,
              AlgorithmIdentifier, ub-name, DirectoryString,
              Attribute, EXTENSION
              FROM PKIX1Explicit93 {iso(1) identified-organization(3)
              dod(6) internet(1) security(5) mechanisms(5) pkix(7)
              id-mod(0) id-pkix1-explicit-93(3)};

– Key and policy information extensions –

authorityKeyIdentifier EXTENSION ::= {

      SYNTAX          AuthorityKeyIdentifier
      IDENTIFIED BY   id-ce-authorityKeyIdentifier }

AuthorityKeyIdentifier ::= SEQUENCE {

  keyIdentifier               [0] KeyIdentifier            OPTIONAL,
  authorityCertIssuer         [1] GeneralNames             OPTIONAL,
  authorityCertSerialNumber   [2] CertificateSerialNumber  OPTIONAL }
      ( WITH COMPONENTS       {..., authorityCertIssuer PRESENT,
                              authorityCertSerialNumber PRESENT} |
       WITH COMPONENTS        {..., authorityCertIssuer ABSENT,
                              authorityCertSerialNumber ABSENT} )

KeyIdentifier ::= OCTET STRING

subjectKeyIdentifier EXTENSION ::= {

      SYNTAX          SubjectKeyIdentifier
      IDENTIFIED BY   id-ce-subjectKeyIdentifier }

SubjectKeyIdentifier ::= KeyIdentifier

keyUsage EXTENSION ::= {

      SYNTAX  KeyUsage
      IDENTIFIED BY id-ce-keyUsage }

Housley, et. al. Standards Track [Page 108] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

KeyUsage ::= BIT STRING {

      digitalSignature     (0),
      nonRepudiation       (1),
      keyEncipherment      (2),
      dataEncipherment     (3),
      keyAgreement         (4),
      keyCertSign          (5),
      cRLSign              (6),
    encipherOnly         (7),
    decipherOnly         (8) }

extendedKeyUsage EXTENSION ::= {

      SYNTAX SEQUENCE SIZE (1..MAX) OF KeyPurposeId
      IDENTIFIED BY id-ce-extKeyUsage }

KeyPurposeId ::= OBJECT IDENTIFIER

– PKIX-defined extended key purpose OIDs id-kp-serverAuth OBJECT IDENTIFIER ::= { id-kp 1 } id-kp-clientAuth OBJECT IDENTIFIER ::= { id-kp 2 } id-kp-codeSigning OBJECT IDENTIFIER ::= { id-kp 3 } id-kp-emailProtection OBJECT IDENTIFIER ::= { id-kp 4 } id-kp-ipsecEndSystem OBJECT IDENTIFIER ::= { id-kp 5 } id-kp-ipsecTunnel OBJECT IDENTIFIER ::= { id-kp 6 } id-kp-ipsecUser OBJECT IDENTIFIER ::= { id-kp 7 } id-kp-timeStamping OBJECT IDENTIFIER ::= { id-kp 8 }

privateKeyUsagePeriod EXTENSION ::= {

      SYNTAX  PrivateKeyUsagePeriod
      IDENTIFIED BY { id-ce-privateKeyUsagePeriod } }

PrivateKeyUsagePeriod ::= SEQUENCE {

      notBefore       [0]     GeneralizedTime OPTIONAL,
      notAfter        [1]     GeneralizedTime OPTIONAL }
      ( WITH COMPONENTS       {..., notBefore PRESENT} |
      WITH COMPONENTS         {..., notAfter PRESENT} )

certificatePolicies EXTENSION ::= {

      SYNTAX  CertificatePoliciesSyntax
      IDENTIFIED BY id-ce-certificatePolicies }

CertificatePoliciesSyntax ::=

              SEQUENCE SIZE (1..MAX) OF PolicyInformation

PolicyInformation ::= SEQUENCE {

      policyIdentifier   CertPolicyId,
      policyQualifiers   SEQUENCE SIZE (1..MAX) OF
              PolicyQualifierInfo OPTIONAL }

Housley, et. al. Standards Track [Page 109] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

CertPolicyId ::= OBJECT IDENTIFIER

PolicyQualifierInfo ::= SEQUENCE {

      policyQualifierId       CERT-POLICY-QUALIFIER.&id
                                  ({SupportedPolicyQualifiers}),
      qualifier               CERT-POLICY-QUALIFIER.&Qualifier
                                  ({SupportedPolicyQualifiers}
                                  {@policyQualifierId})OPTIONAL }

SupportedPolicyQualifiers CERT-POLICY-QUALIFIER ::= { noticeToUser |

                                                    pointerToCPS }

CERT-POLICY-QUALIFIER ::= CLASS {

      &id             OBJECT IDENTIFIER UNIQUE,
      &Qualifier      OPTIONAL }

WITH SYNTAX {

      POLICY-QUALIFIER-ID     &id
      [QUALIFIER-TYPE &Qualifier] }

policyMappings EXTENSION ::= {

      SYNTAX  PolicyMappingsSyntax
      IDENTIFIED BY id-ce-policyMappings }

PolicyMappingsSyntax ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {

      issuerDomainPolicy           CertPolicyId,
      subjectDomainPolicy          CertPolicyId }

– Certificate subject and certificate issuer attributes extensions –

subjectAltName EXTENSION ::= {

      SYNTAX  GeneralNames
      IDENTIFIED BY id-ce-subjectAltName }

GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName

GeneralName ::= CHOICE {

      otherName                   [0] INSTANCE OF OTHER-NAME,
      rfc822Name                  [1] IA5String,
      dNSName                     [2] IA5String,
      x400Address                 [3] ORAddress,
      directoryName               [4] Name,
      ediPartyName                [5] EDIPartyName,
      uniformResourceIdentifier   [6] IA5String,
      iPAddress                   [7] OCTET STRING,
      registeredID                [8] OBJECT IDENTIFIER }

OTHER-NAME ::= TYPE-IDENTIFIER

Housley, et. al. Standards Track [Page 110] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

EDIPartyName ::= SEQUENCE {

      nameAssigner        [0] DirectoryString {ub-name} OPTIONAL,
      partyName           [1] DirectoryString {ub-name} }

issuerAltName EXTENSION ::= {

      SYNTAX  GeneralNames
      IDENTIFIED BY id-ce-issuerAltName }

subjectDirectoryAttributes EXTENSION ::= {

      SYNTAX  AttributesSyntax
      IDENTIFIED BY id-ce-subjectDirectoryAttributes }

AttributesSyntax ::= SEQUENCE SIZE (1..MAX) OF Attribute

– Certification path constraints extensions –

basicConstraints EXTENSION ::= {

      SYNTAX  BasicConstraintsSyntax
      IDENTIFIED BY id-ce-basicConstraints }

BasicConstraintsSyntax ::= SEQUENCE {

      cA                      BOOLEAN DEFAULT FALSE,
      pathLenConstraint       INTEGER (0..MAX) OPTIONAL }

nameConstraints EXTENSION ::= {

      SYNTAX  NameConstraintsSyntax
      IDENTIFIED BY id-ce-nameConstraints }

NameConstraintsSyntax ::= SEQUENCE {

      permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
      excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }

GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree

GeneralSubtree ::= SEQUENCE {

      base                    GeneralName,
      minimum         [0]     BaseDistance DEFAULT 0,
      maximum         [1]     BaseDistance OPTIONAL }

BaseDistance ::= INTEGER (0..MAX)

policyConstraints EXTENSION ::= {

      SYNTAX  PolicyConstraintsSyntax
      IDENTIFIED BY id-ce-policyConstraints }

PolicyConstraintsSyntax ::= SEQUENCE {

      requireExplicitPolicy   [0] SkipCerts OPTIONAL,
      inhibitPolicyMapping    [1] SkipCerts OPTIONAL }

Housley, et. al. Standards Track [Page 111] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

SkipCerts ::= INTEGER (0..MAX)

– Basic CRL extensions –

cRLNumber EXTENSION ::= {

      SYNTAX  CRLNumber
      IDENTIFIED BY id-ce-cRLNumber }

CRLNumber ::= INTEGER (0..MAX)

reasonCode EXTENSION ::= {

      SYNTAX  CRLReason
      IDENTIFIED BY id-ce-reasonCode }

CRLReason ::= ENUMERATED {

      unspecified             (0),
      keyCompromise           (1),
      cACompromise            (2),
      affiliationChanged      (3),
      superseded              (4),
      cessationOfOperation    (5),
      certificateHold         (6),
      removeFromCRL           (8) }

instructionCode EXTENSION ::= {

      SYNTAX  HoldInstruction
      IDENTIFIED BY id-ce-instructionCode }

HoldInstruction ::= OBJECT IDENTIFIER

– holdinstructions described in this specification, from ANSI x9

– ANSI x9 arc holdinstruction arc holdInstruction OBJECT IDENTIFIER ::= {

   joint-iso-ccitt(2) member-body(2) us(840) x9cm(10040) 2}

– ANSI X9 holdinstructions referenced by this standard id-holdinstruction-none OBJECT IDENTIFIER ::= {holdInstruction 1} id-holdinstruction-callissuer OBJECT IDENTIFIER ::= {holdInstruction 2} id-holdinstruction-reject OBJECT IDENTIFIER ::= {holdInstruction 3}

invalidityDate EXTENSION ::= {

      SYNTAX  GeneralizedTime
      IDENTIFIED BY id-ce-invalidityDate }

– CRL distribution points and delta-CRL extensions –

cRLDistributionPoints EXTENSION ::= {

Housley, et. al. Standards Track [Page 112] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

      SYNTAX  CRLDistPointsSyntax
      IDENTIFIED BY id-ce-cRLDistributionPoints }

CRLDistPointsSyntax ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint

DistributionPoint ::= SEQUENCE {

      distributionPoint       [0]     DistributionPointName OPTIONAL,
      reasons         [1]     ReasonFlags OPTIONAL,
      cRLIssuer               [2]     GeneralNames OPTIONAL }

DistributionPointName ::= CHOICE {

      fullName                [0]     GeneralNames,
      nameRelativeToCRLIssuer [1]     RelativeDistinguishedName }

ReasonFlags ::= BIT STRING {

      unused                  (0),
      keyCompromise           (1),
      caCompromise            (2),
      affiliationChanged      (3),
      superseded              (4),
      cessationOfOperation    (5),
      certificateHold         (6) }

issuingDistributionPoint EXTENSION ::= {

      SYNTAX  IssuingDistPointSyntax
      IDENTIFIED BY id-ce-issuingDistributionPoint }

IssuingDistPointSyntax ::= SEQUENCE {

      distributionPoint       [0] DistributionPointName OPTIONAL,
      onlyContainsUserCerts   [1] BOOLEAN DEFAULT FALSE,
      onlyContainsCACerts     [2] BOOLEAN DEFAULT FALSE,
      onlySomeReasons         [3] ReasonFlags OPTIONAL,
      indirectCRL             [4] BOOLEAN DEFAULT FALSE }

certificateIssuer EXTENSION ::= {

      SYNTAX          GeneralNames
      IDENTIFIED BY id-ce-certificateIssuer }

deltaCRLIndicator EXTENSION ::= {

      SYNTAX          BaseCRLNumber
      IDENTIFIED BY id-ce-deltaCRLIndicator }

BaseCRLNumber ::= CRLNumber

– Object identifier assignments for ISO certificate extensions – id-ce OBJECT IDENTIFIER ::= {joint-iso-ccitt(2) ds(5) 29}

id-ce-subjectDirectoryAttributes OBJECT IDENTIFIER ::= {id-ce 9}

Housley, et. al. Standards Track [Page 113] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

id-ce-subjectKeyIdentifier OBJECT IDENTIFIER ::= {id-ce 14} id-ce-keyUsage OBJECT IDENTIFIER ::= {id-ce 15} id-ce-privateKeyUsagePeriod OBJECT IDENTIFIER ::= {id-ce 16} id-ce-subjectAltName OBJECT IDENTIFIER ::= {id-ce 17} id-ce-issuerAltName OBJECT IDENTIFIER ::= {id-ce 18} id-ce-basicConstraints OBJECT IDENTIFIER ::= {id-ce 19} id-ce-cRLNumber OBJECT IDENTIFIER ::= {id-ce 20} id-ce-reasonCode OBJECT IDENTIFIER ::= {id-ce 21} id-ce-instructionCode OBJECT IDENTIFIER ::= {id-ce 23} id-ce-invalidityDate OBJECT IDENTIFIER ::= {id-ce 24} id-ce-deltaCRLIndicator OBJECT IDENTIFIER ::= {id-ce 27} id-ce-issuingDistributionPoint OBJECT IDENTIFIER ::= {id-ce 28} id-ce-certificateIssuer OBJECT IDENTIFIER ::= {id-ce 29} id-ce-nameConstraints OBJECT IDENTIFIER ::= {id-ce 30} id-ce-cRLDistributionPoints OBJECT IDENTIFIER ::= {id-ce 31} id-ce-certificatePolicies OBJECT IDENTIFIER ::= {id-ce 32} id-ce-policyMappings OBJECT IDENTIFIER ::= {id-ce 33} id-ce-policyConstraints OBJECT IDENTIFIER ::= {id-ce 36} id-ce-authorityKeyIdentifier OBJECT IDENTIFIER ::= {id-ce 35} id-ce-extKeyUsage OBJECT IDENTIFIER ::= {id-ce 37}

– PKIX 1 extensions

authorityInfoAccess EXTENSION ::= {

      SYNTAX  AuthorityInfoAccessSyntax
      IDENTIFIED BY id-pe-authorityInfoAccess }

AuthorityInfoAccessSyntax ::=

      SEQUENCE SIZE (1..MAX) OF AccessDescription

AccessDescription ::= SEQUENCE {

      accessMethod          OBJECT IDENTIFIER,
      accessLocation        GeneralName  }

id-pe-authorityInfoAccess OBJECT IDENTIFIER ::= { id-pe 1 }

id-ad-ocsp OBJECT IDENTIFIER ::= { id-ad 1 } id-ad-caIssuers OBJECT IDENTIFIER ::= { id-ad 2 }

– PKIX policy qualifier definitions

noticeToUser CERT-POLICY-QUALIFIER ::= {

   POLICY-QUALIFIER-ID    id-qt-cps QUALIFIER-TYPE       CPSuri}

pointerToCPS CERT-POLICY-QUALIFIER ::= {

   POLICY-QUALIFIER-ID    id-qt-unotice QUALIFIER-TYPE   UserNotice}

id-qt-cps OBJECT IDENTIFIER ::= { id-qt 1 }

Housley, et. al. Standards Track [Page 114] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

id-qt-unotice OBJECT IDENTIFIER ::= { id-qt 2 }

CPSuri ::= IA5String

UserNotice ::= SEQUENCE {

   noticeRef        NoticeReference OPTIONAL,
   explicitText     DisplayText OPTIONAL}

NoticeReference ::= SEQUENCE {

   organization     DisplayText,
   noticeNumbers    SEQUENCE OF INTEGER }

DisplayText ::= CHOICE {

   visibleString    VisibleString  (SIZE (1..200)),
   bmpString        BMPString      (SIZE (1..200)),
   utf8String       UTF8String     (SIZE (1..200)) }

END

Housley, et. al. Standards Track [Page 115] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

Appendix C. ASN.1 Notes

 The construct "SEQUENCE SIZE (1..MAX) OF" appears in several ASN.1
 constructs. A valid ASN.1 sequence will have zero or more entries.
 The SIZE (1..MAX) construct constrains the sequence to have at least
 one entry. MAX indicates the upper bound is unspecified.
 Implementations are free to choose an upper bound that suits their
 environment.
 The construct "positiveInt ::= INTEGER (0..MAX)" defines positiveInt
 as a subtype of INTEGER containing integers greater than or equal to
 zero.  The upper bound is unspecified. Implementations are free to
 select an upper bound that suits their environment.
 The character string type PrintableString supports a very basic Latin
 character set:  the lower case letters 'a' through 'z', upper case
 letters 'A' through 'Z', the digits '0' through '9', eleven special
 characters ' " ( ) + , - . / : ? and space.
 The character string type TeletexString is a superset of
 PrintableString.  TeletexString supports a fairly standard (ascii-
 like) Latin character set, Latin characters with non-spacing accents
 and Japanese characters.
 The character string type UniversalString supports any of the
 characters allowed by ISO 10646-1. ISO 10646 is the Universal
 multiple-octet coded Character Set (UCS).  ISO 10646-1 specifes the
 architecture and the "basic multilingual plane" - a large standard
 character set which includes all major world character standards.
 The character string type UTF8String will be introduced in the 1998
 version of ASN.1.  UTF8String is a universal type and has been
 assigned tag number 12.  The content of UTF8String was defined by RFC
 2044 and updated in RFC 2279, "UTF-8, a transformation Format of ISP
 10646."  ISO is expected to formally add UTF8String to the list of
 choices for DirectoryString in 1998 as well.
 In anticipation of these changes, and in conformance with IETF Best
 Practices codified in RFC 2277, IETF Policy on Character Sets and
 Languages, this document includes UTF8String as a choice in
 DirectoryString and the CPS qualifier extensions.

Housley, et. al. Standards Track [Page 116] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

Appendix D. Examples

 This section contains four examples: three certificates and a CRL.
 The first two certificates and the CRL comprise a minimal
 certification path.
 Section D.1 contains an annotated hex dump of a "self-signed"
 certificate issued by a CA whose distinguished name is
 cn=us,o=gov,ou=nist.  The certificate contains a DSA public key with
 parameters, and is signed by the corresponding DSA private key.
 Section D.2 contains an annotated hex dump of an end-entity
 certificate.  The end entity certificate contains a DSA public key,
 and is signed by the private key corresponding to the "self-signed"
 certificate in section D.1.
 Section D.3 contains a dump of an end entity certificate which
 contains an RSA public key and is signed with RSA and MD5.  This
 certificate is not part of the minimal certification path.
 Section D.4 contains an annotated hex dump of a CRL.  The CRL is
 issued by the CA whose distinguished name is cn=us,o=gov,ou=nist and
 the list of revoked certificates includes the end entity certificate
 presented in D.2.

D.1 Certificate

 This section contains an annotated hex dump of a 699 byte version 3
 certificate.  The certificate contains the following information:
 (a) the serial number is 17 (11 hex);
 (b) the certificate is signed with DSA and the SHA-1 hash algorithm;
 (c) the issuer's distinguished name is OU=nist; O=gov; C=US
 (d) and the subject's distinguished name is OU=nist; O=gov; C=US
 (e) the certificate was issued on June 30, 1997 and will expire on
 December 31, 1997;
 (f) the certificate contains a 1024 bit DSA public key with
 parameters;
 (g) the certificate contains a subject key identifier extension; and
 (h) the certificate is a CA certificate (as indicated through the
 basic constraints extension.)

0000 30 82 02 b7 695: SEQUENCE 0004 30 82 02 77 631: . SEQUENCE tbscertificate 0008 a0 03 3: . . [0] 0010 02 01 1: . . . INTEGER 2

                   : 02

0013 02 01 1: . . INTEGER 17

                   : 11

Housley, et. al. Standards Track [Page 117] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

0016 30 09 9: . . SEQUENCE 0018 06 07 7: . . . OID 1.2.840.10040.4.3: dsa-with-sha

                   : 2a 86 48 ce 38 04 03

0027 30 2a 42: . . SEQUENCE 0029 31 0b 11: . . . SET 0031 30 09 9: . . . . SEQUENCE 0033 06 03 3: . . . . . OID 2.5.4.6: C

                   : 55 04 06

0038 13 02 2: . . . . . PrintableString 'US'

                   : 55 53

0042 31 0c 12: . . . SET 0044 30 0a 10: . . . . SEQUENCE 0046 06 03 3: . . . . . OID 2.5.4.10: O

                   : 55 04 0a

0051 13 03 3: . . . . . PrintableString 'gov'

                   : 67 6f 76

0056 31 0d 13: . . . SET 0058 30 0b 11: . . . . SEQUENCE 0060 06 03 3: . . . . . OID 2.5.4.11: OU

                   : 55 04 0b

0065 13 04 4: . . . . . PrintableString 'nist'

                   : 6e 69 73 74

0071 30 1e 30: . . SEQUENCE 0073 17 0d 13: . . . UTCTime '970630000000Z'

                   : 39 37 30 36 33 30 30 30 30 30 30 30 5a

0088 17 0d 13: . . . UTCTime '971231000000Z'

                   : 39 37 31 32 33 31 30 30 30 30 30 30 5a

0103 30 2a 42: . . SEQUENCE 0105 31 0b 11: . . . SET 0107 30 09 9: . . . . SEQUENCE 0109 06 03 3: . . . . . OID 2.5.4.6: C

                   : 55 04 06

0114 13 02 2: . . . . . PrintableString 'US'

                   : 55 53

0118 31 0c 12: . . . SET 0120 30 0a 10: . . . . SEQUENCE 0122 06 03 3: . . . . . OID 2.5.4.10: O

                   : 55 04 0a

0127 13 03 3: . . . . . PrintableString 'gov'

                   : 67 6f 76

0132 31 0d 13: . . . SET 0134 30 0b 11: . . . . SEQUENCE 0136 06 03 3: . . . . . OID 2.5.4.11: OU

                   : 55 04 0b

0141 13 04 4: . . . . . PrintableString 'nist'

                   : 6e 69 73 74

0147 30 82 01 b4 436: . . SEQUENCE 0151 30 82 01 29 297: . . . SEQUENCE

Housley, et. al. Standards Track [Page 118] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

0155 06 07 7: . . . . OID 1.2.840.10040.4.1: dsa

                   : 2a 86 48 ce 38 04 01

0164 30 82 01 1c 284: . . . . SEQUENCE 0168 02 81 80 128: . . . . . INTEGER

                   : d4 38 02 c5 35 7b d5 0b a1 7e 5d 72 59 63 55 d3
                   : 45 56 ea e2 25 1a 6b c5 a4 ab aa 0b d4 62 b4 d2
                   : 21 b1 95 a2 c6 01 c9 c3 fa 01 6f 79 86 83 3d 03
                   : 61 e1 f1 92 ac bc 03 4e 89 a3 c9 53 4a f7 e2 a6
                   : 48 cf 42 1e 21 b1 5c 2b 3a 7f ba be 6b 5a f7 0a
                   : 26 d8 8e 1b eb ec bf 1e 5a 3f 45 c0 bd 31 23 be
                   : 69 71 a7 c2 90 fe a5 d6 80 b5 24 dc 44 9c eb 4d
                   : f9 da f0 c8 e8 a2 4c 99 07 5c 8e 35 2b 7d 57 8d

0299 02 14 20: . . . . . INTEGER

                   : a7 83 9b f3 bd 2c 20 07 fc 4c e7 e8 9f f3 39 83
                   : 51 0d dc dd

0321 02 81 80 128: . . . . . INTEGER

                   : 0e 3b 46 31 8a 0a 58 86 40 84 e3 a1 22 0d 88 ca
                   : 90 88 57 64 9f 01 21 e0 15 05 94 24 82 e2 10 90
                   : d9 e1 4e 10 5c e7 54 6b d4 0c 2b 1b 59 0a a0 b5
                   : a1 7d b5 07 e3 65 7c ea 90 d8 8e 30 42 e4 85 bb
                   : ac fa 4e 76 4b 78 0e df 6c e5 a6 e1 bd 59 77 7d
                   : a6 97 59 c5 29 a7 b3 3f 95 3e 9d f1 59 2d f7 42
                   : 87 62 3f f1 b8 6f c7 3d 4b b8 8d 74 c4 ca 44 90
                   : cf 67 db de 14 60 97 4a d1 f7 6d 9e 09 94 c4 0d

0452 03 81 84 132: . . . BIT STRING (0 unused bits)

                   : 02 81 80 aa 98 ea 13 94 a2 db f1 5b 7f 98 2f 78
                   : e7 d8 e3 b9 71 86 f6 80 2f 40 39 c3 da 3b 4b 13
                   : 46 26 ee 0d 56 c5 a3 3a 39 b7 7d 33 c2 6b 5c 77
                   : 92 f2 55 65 90 39 cd 1a 3c 86 e1 32 eb 25 bc 91
                   : c4 ff 80 4f 36 61 bd cc e2 61 04 e0 7e 60 13 ca
                   : c0 9c dd e0 ea 41 de 33 c1 f1 44 a9 bc 71 de cf
                   : 59 d4 6e da 44 99 3c 21 64 e4 78 54 9d d0 7b ba
                   : 4e f5 18 4d 5e 39 30 bf e0 d1 f6 f4 83 25 4f 14
                   : aa 71 e1

0587 a3 32 50: . . [3] 0589 30 30 48: . . . SEQUENCE 0591 30 0f 9: . . . . SEQUENCE 0593 06 03 3: . . . . . OID 2.5.29.19: basicConstraints

                   : 55 1d 13

0598 01 01 1: . . . . . TRUE

                   : ff

0601 04 05 5: . . . . . OCTET STRING

                   : 30 03 01 01 ff

0608 30 1d 29: . SEQUENCE 0610 06 03 3: . . . . . OID 2.5.29.14: subjectKeyIdentifier

                   : 55 1d 0e

0615 04 16 22: . . . . . OCTET STRING

                   : 04 14 e7 26 c5 54 cd 5b a3 6f 35 68 95 aa d5 ff

Housley, et. al. Standards Track [Page 119] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

                   : 1c 21 e4 22 75 d6

0639 30 09 9: . SEQUENCE 0641 06 07 7: . . OID 1.2.840.10040.4.3: dsa-with-sha

                   : 2a 86 48 ce 38 04 03

0650 03 2f 47: . BIT STRING (0 unused bits)

                   : 30 2c 02 14 a0 66 c1 76 33 99 13 51 8d 93 64 2f
                   : ca 13 73 de 79 1a 7d 33 02 14 5d 90 f6 ce 92 4a
                   : bf 29 11 24 80 28 a6 5a 8e 73 b6 76 02 68

D.2 Certificate

 This section contains an annotated hex dump of a 730 byte version 3
 certificate.  The certificate contains the following information:
 (a) the serial number is 18 (12 hex);
 (b) the certificate is signed with DSA and the SHA-1 hash algorithm;
 (c) the issuer's distinguished name is OU=nist; O=gov; C=US
 (d) and the subject's distinguished name is CN=Tim Polk; OU=nist;
 O=gov; C=US
 (e) the certificate was valid from July 30, 1997 through December 1,
 1997;
 (f) the certificate contains a 1024 bit DSA public key;
 (g) the certificate is an end entity certificate, as the basic
 constraints extension is not present;
 (h) the certificate contains an authority key identifier extension;
 and
 (i) the certificate includes one alternative name - an RFC 822
 address.

0000 30 82 02 d6 726: SEQUENCE 0004 30 82 02 96 662: . SEQUENCE 0008 a0 03 3: . . [0] 0010 02 01 1: . . . INTEGER 2

                   : 02

0013 02 01 1: . . INTEGER 18

                   : 12

0016 30 09 9: . . SEQUENCE 0018 06 07 7: . . . OID 1.2.840.10040.4.3: dsa-with-sha

                   : 2a 86 48 ce 38 04 03

0027 30 2a 42: . . SEQUENCE 0029 31 0b 11: . . . SET 0031 30 09 9: . . . . SEQUENCE 0033 06 03 3: . . . . . OID 2.5.4.6: C

                   : 55 04 06

0038 13 02 2: . . . . . PrintableString 'US'

                   : 55 53

0042 31 0c 12: . . . SET 0044 30 0a 10: . . . . SEQUENCE 0046 06 03 3: . . . . . OID 2.5.4.10: O

Housley, et. al. Standards Track [Page 120] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

                   : 55 04 0a

0051 13 03 3: . . . . . PrintableString 'gov'

                   : 67 6f 76

0056 31 0d 13: . . . SET 0058 30 0b 11: . . . . SEQUENCE 0060 06 03 3: . . . . . OID 2.5.4.11: OU

                   : 55 04 0b

0065 13 04 4: . . . . . PrintableString 'nist'

                   : 6e 69 73 74

0071 30 1e 30: . . SEQUENCE 0073 17 0d 13: . . . UTCTime '970730000000Z'

                   : 39 37 30 37 33 30 30 30 30 30 30 30 5a

0088 17 0d 13: . . . UTCTime '971201000000Z'

                   : 39 37 31 32 30 31 30 30 30 30 30 30 5a

0103 30 3d 61: . . SEQUENCE 0105 31 0b 11: . . . SET 0107 30 09 9: . . . . SEQUENCE 0109 06 03 3: . . . . . OID 2.5.4.6: C

                   : 55 04 06

0114 13 02 2: . . . . . PrintableString 'US'

                   : 55 53

0118 31 0c 12: . . . SET 0120 30 0a 10: . . . . SEQUENCE 0122 06 03 3: . . . . . OID 2.5.4.10: O

                   : 55 04 0a

0127 13 03 3: . . . . . PrintableString 'gov'

                   : 67 6f 76

0132 31 0d 13: . . . SET 0134 30 0b 11: . . . . SEQUENCE 0136 06 03 3: . . . . . OID 2.5.4.11: OU

                   : 55 04 0b

0141 13 04 4: . . . . . PrintableString 'nist'

                   : 6e 69 73 74

0147 31 11 17: . . . SET 0149 30 0f 15: . . . . SEQUENCE 0151 06 03 3: . . . . . OID 2.5.4.3: CN

                   : 55 04 03

0156 13 08 8: . . . . . PrintableString 'Tim Polk'

                   : 54 69 6d 20 50 6f 6c 6b

0166 30 82 01 b4 436: . . SEQUENCE 0170 30 82 01 29 297: . . . SEQUENCE 0174 06 07 7: . . . . OID 1.2.840.10040.4.1: dsa

                   : 2a 86 48 ce 38 04 01

0183 30 82 01 1c 284: . . . . SEQUENCE 0187 02 81 80 128: . . . . . INTEGER

                   : d4 38 02 c5 35 7b d5 0b a1 7e 5d 72 59 63 55 d3
                   : 45 56 ea e2 25 1a 6b c5 a4 ab aa 0b d4 62 b4 d2
                   : 21 b1 95 a2 c6 01 c9 c3 fa 01 6f 79 86 83 3d 03

Housley, et. al. Standards Track [Page 121] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

                   : 61 e1 f1 92 ac bc 03 4e 89 a3 c9 53 4a f7 e2 a6
                   : 48 cf 42 1e 21 b1 5c 2b 3a 7f ba be 6b 5a f7 0a
                   : 26 d8 8e 1b eb ec bf 1e 5a 3f 45 c0 bd 31 23 be
                   : 69 71 a7 c2 90 fe a5 d6 80 b5 24 dc 44 9c eb 4d
                   : f9 da f0 c8 e8 a2 4c 99 07 5c 8e 35 2b 7d 57 8d

0318 02 14 20: . . . . . INTEGER

                   : a7 83 9b f3 bd 2c 20 07 fc 4c e7 e8 9f f3 39 83
                   : 51 0d dc dd

0340 02 81 80 128: . . . . . INTEGER

                   : 0e 3b 46 31 8a 0a 58 86 40 84 e3 a1 22 0d 88 ca
                   : 90 88 57 64 9f 01 21 e0 15 05 94 24 82 e2 10 90
                   : d9 e1 4e 10 5c e7 54 6b d4 0c 2b 1b 59 0a a0 b5
                   : a1 7d b5 07 e3 65 7c ea 90 d8 8e 30 42 e4 85 bb
                   : ac fa 4e 76 4b 78 0e df 6c e5 a6 e1 bd 59 77 7d
                   : a6 97 59 c5 29 a7 b3 3f 95 3e 9d f1 59 2d f7 42
                   : 87 62 3f f1 b8 6f c7 3d 4b b8 8d 74 c4 ca 44 90
                   : cf 67 db de 14 60 97 4a d1 f7 6d 9e 09 94 c4 0d

0471 03 81 84 132: . . . BIT STRING (0 unused bits)

                   : 02 81 80 a8 63 b1 60 70 94 7e 0b 86 08 93 0c 0d
                   : 08 12 4a 58 a9 af 9a 09 38 54 3b 46 82 fb 85 0d
                   : 18 8b 2a 77 f7 58 e8 f0 1d d2 18 df fe e7 e9 35
                   : c8 a6 1a db 8d 3d 3d f8 73 14 a9 0b 39 c7 95 f6
                   : 52 7d 2d 13 8c ae 03 29 3c 4e 8c b0 26 18 b6 d8
                   : 11 1f d4 12 0c 13 ce 3f f1 c7 05 4e df e1 fc 44
                   : fd 25 34 19 4a 81 0d dd 98 42 ac d3 b6 91 0c 7f
                   : 16 72 a3 a0 8a d7 01 7f fb 9c 93 e8 99 92 c8 42
                   : 47 c6 43

0606 a3 3e 62: . . [3] 0608 30 3c 60: . . . SEQUENCE 0610 30 19 25: . . . . SEQUENCE 0612 06 03 3: . . . . . OID 2.5.29.17: subjectAltName

                   : 55 1d 11

0617 04 12 18: . . . . . OCTET STRING

                   : 30 10 81 0e 77 70 6f 6c 6b 40 6e 69 73 74 2e 67
                   : 6f 76

0637 30 1f 31: . . . . SEQUENCE 0639 06 03 3: . . . . . OID 2.5.29.35: subjectAltName

                   : 55 1d 23

0644 04 18 24: . . . . . OCTET STRING

                   : 30 16 80 14 e7 26 c5 54 cd 5b a3 6f 35 68 95 aa
                   : d5 ff 1c 21 e4 22 75 d6

0670 30 09 9: . SEQUENCE 0672 06 07 7: . . OID 1.2.840.10040.4.3: dsa-with-sha

                   : 2a 86 48 ce 38 04 03

0681 03 2f 47: . BIT STRING (0 unused bits)

                   : 30 2c 02 14 3c 02 e0 ab d9 5d 05 77 75 15 71 58
                   : 92 29 48 c4 1c 54 df fc 02 14 5b da 53 98 7f c5
                   : 33 df c6 09 b2 7a e3 6f 97 70 1e 14 ed 94

Housley, et. al. Standards Track [Page 122] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

D.3 End-Entity Certificate Using RSA

 This section contains an annotated hex dump of a 675 byte version 3
 certificate.  The certificate contains the following information:
 (a) the serial number is 256;
 (b) the certificate is signed with RSA and the MD2 hash algorithm;
 (c) the issuer's distinguished name is OU=Dept. Arquitectura de
 Computadors; O=Universitat Politecnica de Catalunya; C=ES
 (d) and the subject's distinguished name is CN=Francisco Jordan;
 OU=Dept. Arquitectura de Computadors; O=Universitat Politecnica de
 Catalunya; C=ES
 (e) the certificate was issued on May 21, 1996 and expired on May 21,
 1997;
 (f) the certificate contains a 768 bit RSA public key;
 (g) the certificate is an end entity certificate (not a CA
 certificate);
 (h) the certificate includes an alternative subject name and an
 alternative issuer name - bothe are URLs;
 (i) the certificate include an authority key identifier and
 certificate policies extensions; and
 (j) the certificate includes a critical key usage extension
 specifying the public is intended for generation of digital
 signatures.

0000 30 80 : SEQUENCE (size undefined) 0002 30 82 02 40 576: . SEQUENCE 0006 a0 03 3: . . [0] 0008 02 01 1: . . . INTEGER 2

                   : 02

0011 02 02 2: . . INTEGER 256

                   : 01 00

0015 30 0d 13: . . SEQUENCE 0017 06 09 9: . . . OID 1.2.840.113549.1.1.2:

                                     MD2WithRSAEncryption
                   : 2a 86 48 86 f7 0d 01 01 02

0028 05 00 0: . . . NULL 0030 30 68 88: . . SEQUENCE 0032 31 0b 11: . . . SET 0034 30 09 9: . . . . SEQUENCE 0036 06 03 3: . . . . . OID 2.5.4.6: C

                   : 55 04 06

0041 13 02 2: . . . . . PrintableString 'ES'

                   : 45 53

0045 31 2d 45: . . . SET 0047 30 2b 43: . . . . SEQUENCE 0049 06 03 3: . . . . . OID 2.5.4.10: O

                   : 55 04 0a

0054 13 24 36: . . . . . PrintableString

Housley, et. al. Standards Track [Page 123] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

                   'Universitat Politecnica de Catalunya'
                   : 55 6e 69 76 65 72 73 69 74 61 74 20 50 6f 6c 69
                   : 74 65 63 6e 69 63 61 20 64 65 20 43 61 74 61 6c
                   : 75 6e 79 61

0092 31 2a 42: . . . SET 0094 30 28 40: . . . . SEQUENCE 0096 06 03 3: . . . . . OID 2.5.4.11: OU

                   : 55 04 0b

0101 13 21 33: . . . . . PrintableString

                   'OU=Dept. Arquitectura de Computadors'
                   : 44 65 70 74 2e 20 41 72 71 75 69 74 65 63 74 75
                   : 72 61 20 64 65 20 43 6f 6d 70 75 74 61 64 6f 72
                   : 73

0136 30 1e 30: . . SEQUENCE 0138 17 0d 13: . . . UTCTime '960521095826Z'

                   : 39 36 30 37 32 32 31 37 33 38 30 32 5a

0153 17 0d 13: . . . UTCTime '979521095826Z'

                   : 39 37 30 37 32 32 31 37 33 38 30 32 5a

0168 30 81 83 112: . . SEQUENCE 0171 31 0b 11: . . . SET 0173 30 09 9: . . . . SEQUENCE 0175 06 03 3: . . . . . OID 2.5.4.6: C

                   : 55 04 06

0180 13 02 2: . . . . . PrintableString 'ES'

                   : 45 53

0184 31 2d 12: . . . SET 0186 30 2b 16: . . . . SEQUENCE 0188 06 03 3: . . . . . OID 2.5.4.10: O

                   : 55 04 0a

0193 13 24 36: . . . . . PrintableString

                   'Universitat Politecnica de Catalunya'
                   : 55 6e 69 76 65 72 73 69 74 61 74 20 50 6f 6c 69
                   : 74 65 63 6e 69 63 61 20 64 65 20 43 61 74 61 6c
                   : 75 6e 79 61

0231 31 2a 42: . . . SET 0233 30 28 40: . . . . SEQUENCE 0235 06 03 3: . . . . . OID 2.5.4.11: OU

                   : 55 04 0b

0240 13 21 33: . . . . . PrintableString

                   'Dept. Arquitectura de Computadors'
                   : 44 65 70 74 2e 20 41 72 71 75 69 74 65 63 74 75
                   : 72 61 20 64 65 20 43 6f 6d 70 75 74 61 64 6f 72
                   : 73

0275 31 19 22: . . . SET 0277 30 17 20: . . . . SEQUENCE 0279 06 03 3: . . . . . OID 2.5.4.3: CN

                   : 55 04 03

0284 13 10 16: . . . . . PrintableString 'Francisco Jordan'

Housley, et. al. Standards Track [Page 124] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

                   : 46 72 61 6e 63 69 73 63 6f 20 4a 6f 72 64 61 6e

0302 30 7c 2: . . SEQUENCE 0304 30 0d 13: . . . SEQUENCE 0306 06 09 9: . . . . OID 1.2.840.113549.1.1.1: RSAEncryption

                   : 2a 86 48 86 f7 0d 01 01 01

0317 05 00 0: . . . . NULL 0319 03 6b 107: . . . BIT STRING

                   : 00   (0 unused bits)
                   : 30 68 02 61 00 be aa 8b 77 54 a3 af ca 77 9f 2f
                   : b0 cf 43 88 ff a6 6d 79 55 5b 61 8c 68 ec 48 1e
                   : 8a 86 38 a4 fe 19 b8 62 17 1d 9d 0f 47 2c ff 63
                   : 8f 29 91 04 d1 52 bc 7f 67 b6 b2 8f 74 55 c1 33
                   : 21 6c 8f ab 01 95 24 c8 b2 73 93 9d 22 61 50 a9
                   : 35 fb 9d 57 50 32 ef 56 52 50 93 ab b1 88 94 78
                   : 56 15 c6 1c 8b 02 03 01 00 01

0428 a3 81 97 151: . . [3] 0431 30 3c 60: . . . SEQUENCE 0433 30 1f 31: . . . . SEQUENCE 0435 06 03 3: . . . . . OID 2.5.29.35: authorityKeyIdentifier

                   : 55 1d 23

0440 04 14 22: . . . . . OCTET STRING

                   : 30 12 80 10 0e 6b 3a bf 04 ea 04 c3 0e 6b 3a bf
                   : 04 ea 04 c3

0464 30 19 25: . . . . SEQUENCE 0466 06 03 3: . . . . . OID 2.5.29.15: keyUsage

                   : 55 1d 0f

0471 01 01 1: . . . . . TRUE 0474 04 04 4: . . . . . OCTET STRING

                   : 03 02 07 80

0480 30 19 25: . . . . SEQUENCE 0482 06 03 3: . . . . . OID 2.5.29.32: certificatePolicies

                   : 55 1d 20

0487 04 21 33: . . . . . OCTET STRING

                   : 30 1f 30 1d 06 04 2a 84 80 00 30 15 30 07 06 05
                   : 2a 84 80 00 01 30 0a 06 05 2a 84 80 00 02 02 01
                   : 0a

0522 30 1c 28: . . . . SEQUENCE 0524 06 03 3: . . . . . OID 2.5.29.17: subjectAltName

                   : 55 1d 11

0529 04 15 21: . . . . . OCTET STRING

                   : 30 13 86 11 68 74 74 70 3a 2f 2f 61 63 2e 75 70
                   : 63 2e 65 73 2f

0552 30 19 25: . . . . SEQUENCE 0554 06 03 3: . . . . . OID 2.5.29.18: issuerAltName

                   : 55 1d 12

0559 04 12 18: . . . . . OCTET STRING

                   : 30 14 86 12 68 74 74 70 3a 2f 2f 77 77 77 2e 75
                   : 70 63 2e 65

Housley, et. al. Standards Track [Page 125] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

0579 30 80 : . SEQUENCE (indefinite length) 0581 06 07 7: . . OID 0583 05 00 0: . . NULL 0585 00 00 0: . . end of contents marker 0587 03 81 81 47: . BIT STRING

                   : 00      (0 unused bits)
                   : 5c 01 bd b5 41 88 87 7a 0e d3 0e 6b 3a bf 04 ea
                   : 04 cb 5f 61 72 3c a3 bd 78 f5 66 17 fe 37 3a ab
                   : eb 67 bf b7 da a8 38 f6 33 15 71 75 2f b9 8c 91
                   : a0 e4 87 ba 4b 43 a0 22 8f d3 a9 86 43 89 e6 50
                   : 5c 01 bd b5 41 88 87 7a 0e d3 0e 6b 3a bf 04 ea
                   : 04 cb 5f 61 72 3c a3 bd 78 f5 66 17 fe 37 3a ab
                   : eb 67 bf b7 da a8 38 f6 33 15 71 75 2f b9 8c 91
                   : a0 e4 87 ba 4b 43 a0 22 8f d3 a9 86 43 89 e6 50

0637 00 00 0: . . end of contents marker

D.4 Certificate Revocation List

 This section contains an annotated hex dump of a version 2 CRL with
 one extension (cRLNumber). The CRL was issued by OU=nist;O=gov;C=us
 on July 7, 1996; the next scheduled issuance was August 7, 1996.  The
 CRL includes one revoked certificates: serial number 18 (12 hex).
 The CRL itself is number 18, and it was signed with DSA and SHA-1.

0000 30 81 ba 186: SEQUENCE 0003 30 7c 124: . SEQUENCE 0005 02 01 1: . . INTEGER 1

                   : 01

0008 30 09 9: . . SEQUENCE 0010 06 07 7: . . . OID 1.2.840.10040.4.3: dsa-with-sha

                   : 2a 86 48 ce 38 04 03

0019 30 2a 42: . . SEQUENCE 0021 31 0b 11: . . . SET 0023 30 09 9: . . . . SEQUENCE 0025 06 03 3: . . . . . OID 2.5.4.6: C

                   : 55 04 06

0030 13 02 2: . . . . . PrintableString 'US'

                   : 55 53

0034 31 0c 12: . . . SET 0036 30 0a 10: . . . . SEQUENCE 0038 06 03 3: . . . . . OID 2.5.4.10: O

                   : 55 04 0a

0043 13 03 3: . . . . . PrintableString 'gov'

                   : 67 6f 76

0048 31 0d 13: . . . SET 0050 30 0b 11: . . . . SEQUENCE 0052 06 03 3: . . . . . OID 2.5.4.11: OU

                   : 55 04 0b

Housley, et. al. Standards Track [Page 126] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

0057 13 04 4: . . . . . PrintableString 'nist'

                   : 6e 69 73 74

0063 17 0d 13: . . UTCTime '970801000000Z'

                   : 39 37 30 38 30 31 30 30 30 30 30 30 5a

0078 17 0d 13: . . UTCTime '970808000000Z'

                   : 39 37 30 38 30 38 30 30 30 30 30 30 5a

0093 30 22 34: . . SEQUENCE 0095 30 20 32: . . . SEQUENCE 0097 02 01 1: . . . . INTEGER 18

                   : 12

0100 17 0d 13: . . . . UTCTime '970731000000Z'

                   : 39 37 30 37 33 31 30 30 30 30 30 30 5a

0115 30 0c 12: . . . . SEQUENCE 0117 30 0a 10: . . . . . SEQUENCE 0119 06 03 3: . . . . . . OID 2.5.29.21: reasonCode

                   : 55 1d 15

0124 04 03 3: . . . . . . OCTET STRING

                   : 0a 01 01

0129 30 09 9: . SEQUENCE 0131 06 07 7: . . OID 1.2.840.10040.4.3: dsa-with-sha

                   : 2a 86 48 ce 38 04 03

0140 03 2f 47: . BIT STRING (0 unused bits)

                   : 30 2c 02 14 9e d8 6b c1 7d c2 c4 02 f5 17 84 f9
                   : 9f 46 7a ca cf b7 05 8a 02 14 9e 43 39 85 dc ea
                   : 14 13 72 93 54 5d 44 44 e5 05 fe 73 9a b2

Housley, et. al. Standards Track [Page 127] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

Appendix E. Authors' Addresses

 Russell Housley
 SPYRUS
 381 Elden Street
 Suite 1120
 Herndon, VA 20170
 USA
 EMail: housley@spyrus.com
 Warwick Ford
 VeriSign, Inc.
 One Alewife Center
 Cambridge, MA 02140
 USA
 EMail: wford@verisign.com
 Tim Polk
 NIST
 Building 820, Room 426
 Gaithersburg, MD 20899
 USA
 EMail: wpolk@nist.gov
 David Solo
 Citicorp
 666 Fifth Ave, 3rd Floor
 New York, NY 10103
 USA
 EMail: david.solo@citicorp.com

Housley, et. al. Standards Track [Page 128] RFC 2459 Internet X.509 Public Key Infrastructure January 1999

Appendix F. Full Copyright Statement

 Copyright (C) The Internet Society (1999).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Housley, et. al. Standards Track [Page 129]

/data/webs/external/dokuwiki/data/pages/rfc/rfc2459.txt · Last modified: 1999/03/31 16:54 (external edit)