GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc4398

Network Working Group S. Josefsson Request for Comments: 4398 March 2006 Obsoletes: 2538 Category: Standards Track

        Storing Certificates in the Domain Name System (DNS)

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 (2006).

Abstract

 Cryptographic public keys are frequently published, and their
 authenticity is demonstrated by certificates.  A CERT resource record
 (RR) is defined so that such certificates and related certificate
 revocation lists can be stored in the Domain Name System (DNS).
 This document obsoletes RFC 2538.

Josefsson Standards Track [Page 1] RFC 4398 Storing Certificates in the DNS February 2006

Table of Contents

 1. Introduction ....................................................3
 2. The CERT Resource Record ........................................3
    2.1. Certificate Type Values ....................................4
    2.2. Text Representation of CERT RRs ............................6
    2.3. X.509 OIDs .................................................6
 3. Appropriate Owner Names for CERT RRs ............................7
    3.1. Content-Based X.509 CERT RR Names ..........................8
    3.2. Purpose-Based X.509 CERT RR Names ..........................9
    3.3. Content-Based OpenPGP CERT RR Names ........................9
    3.4. Purpose-Based OpenPGP CERT RR Names .......................10
    3.5. Owner Names for IPKIX, ISPKI, IPGP, and IACPKIX ...........10
 4. Performance Considerations .....................................11
 5. Contributors ...................................................11
 6. Acknowledgements ...............................................11
 7. Security Considerations ........................................12
 8. IANA Considerations ............................................12
 9. Changes since RFC 2538 .........................................13
 10. References ....................................................14
    10.1. Normative References .....................................14
    10.2. Informative References ...................................15
 Appendix A.  Copying Conditions ...................................16

Josefsson Standards Track [Page 2] RFC 4398 Storing Certificates in the DNS February 2006

1. Introduction

 Public keys are frequently published in the form of a certificate,
 and their authenticity is commonly demonstrated by certificates and
 related certificate revocation lists (CRLs).  A certificate is a
 binding, through a cryptographic digital signature, of a public key,
 a validity interval and/or conditions, and identity, authorization,
 or other information.  A certificate revocation list is a list of
 certificates that are revoked, and of incidental information, all
 signed by the signer (issuer) of the revoked certificates.  Examples
 are X.509 certificates/CRLs in the X.500 directory system or OpenPGP
 certificates/revocations used by OpenPGP software.
 Section 2 specifies a CERT resource record (RR) for the storage of
 certificates in the Domain Name System [1] [2].
 Section 3 discusses appropriate owner names for CERT RRs.
 Sections 4, 7, and 8 cover performance, security, and IANA
 considerations, respectively.
 Section 9 explains the changes in this document compared to RFC 2538.
 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 [3].

2. The CERT Resource Record

 The CERT resource record (RR) has the structure given below.  Its RR
 type code is 37.
                     1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             type              |             key tag           |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |   algorithm   |                                               /
 +---------------+            certificate or CRL                 /
 /                                                               /
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
 The type field is the certificate type as defined in Section 2.1
 below.
 The key tag field is the 16-bit value computed for the key embedded
 in the certificate, using the RRSIG Key Tag algorithm described in
 Appendix B of [12].  This field is used as an efficiency measure to

Josefsson Standards Track [Page 3] RFC 4398 Storing Certificates in the DNS February 2006

 pick which CERT RRs may be applicable to a particular key.  The key
 tag can be calculated for the key in question, and then only CERT RRs
 with the same key tag need to be examined.  Note that two different
 keys can have the same key tag.  However, the key MUST be transformed
 to the format it would have as the public key portion of a DNSKEY RR
 before the key tag is computed.  This is only possible if the key is
 applicable to an algorithm and complies to limits (such as key size)
 defined for DNS security.  If it is not, the algorithm field MUST be
 zero and the tag field is meaningless and SHOULD be zero.
 The algorithm field has the same meaning as the algorithm field in
 DNSKEY and RRSIG RRs [12], except that a zero algorithm field
 indicates that the algorithm is unknown to a secure DNS, which may
 simply be the result of the algorithm not having been standardized
 for DNSSEC [11].

2.1. Certificate Type Values

 The following values are defined or reserved:
       Value  Mnemonic  Certificate Type
       -----  --------  ----------------
           0            Reserved
           1  PKIX      X.509 as per PKIX
           2  SPKI      SPKI certificate
           3  PGP       OpenPGP packet
           4  IPKIX     The URL of an X.509 data object
           5  ISPKI     The URL of an SPKI certificate
           6  IPGP      The fingerprint and URL of an OpenPGP packet
           7  ACPKIX    Attribute Certificate
           8  IACPKIX   The URL of an Attribute Certificate
       9-252            Available for IANA assignment
         253  URI       URI private
         254  OID       OID private
         255            Reserved
   256-65279            Available for IANA assignment
 65280-65534            Experimental
       65535            Reserved
 These values represent the initial content of the IANA registry; see
 Section 8.
 The PKIX type is reserved to indicate an X.509 certificate conforming
 to the profile defined by the IETF PKIX working group [8].  The
 certificate section will start with a one-octet unsigned OID length
 and then an X.500 OID indicating the nature of the remainder of the

Josefsson Standards Track [Page 4] RFC 4398 Storing Certificates in the DNS February 2006

 certificate section (see Section 2.3, below).  (NOTE: X.509
 certificates do not include their X.500 directory-type-designating
 OID as a prefix.)
 The SPKI and ISPKI types are reserved to indicate the SPKI
 certificate format [15], for use when the SPKI documents are moved
 from experimental status.  The format for these two CERT RR types
 will need to be specified later.
 The PGP type indicates an OpenPGP packet as described in [5] and its
 extensions and successors.  This is used to transfer public key
 material and revocation signatures.  The data is binary and MUST NOT
 be encoded into an ASCII armor.  An implementation SHOULD process
 transferable public keys as described in Section 10.1 of [5], but it
 MAY handle additional OpenPGP packets.
 The ACPKIX type indicates an Attribute Certificate format [9].
 The IPKIX and IACPKIX types indicate a URL that will serve the
 content that would have been in the "certificate, CRL, or URL" field
 of the corresponding type (PKIX or ACPKIX, respectively).
 The IPGP type contains both an OpenPGP fingerprint for the key in
 question, as well as a URL.  The certificate portion of the IPGP CERT
 RR is defined as a one-octet fingerprint length, followed by the
 OpenPGP fingerprint, followed by the URL.  The OpenPGP fingerprint is
 calculated as defined in RFC 2440 [5].  A zero-length fingerprint or
 a zero-length URL are legal, and indicate URL-only IPGP data or
 fingerprint-only IPGP data, respectively.  A zero-length fingerprint
 and a zero-length URL are meaningless and invalid.
 The IPKIX, ISPKI, IPGP, and IACPKIX types are known as "indirect".
 These types MUST be used when the content is too large to fit in the
 CERT RR and MAY be used at the implementer's discretion.  They SHOULD
 NOT be used where the DNS message is 512 octets or smaller and could
 thus be expected to fit a UDP packet.
 The URI private type indicates a certificate format defined by an
 absolute URI.  The certificate portion of the CERT RR MUST begin with
 a null-terminated URI [10], and the data after the null is the
 private format certificate itself.  The URI SHOULD be such that a
 retrieval from it will lead to documentation on the format of the
 certificate.  Recognition of private certificate types need not be
 based on URI equality but can use various forms of pattern matching
 so that, for example, subtype or version information can also be
 encoded into the URI.

Josefsson Standards Track [Page 5] RFC 4398 Storing Certificates in the DNS February 2006

 The OID private type indicates a private format certificate specified
 by an ISO OID prefix.  The certificate section will start with a
 one-octet unsigned OID length and then a BER-encoded OID indicating
 the nature of the remainder of the certificate section.  This can be
 an X.509 certificate format or some other format.  X.509 certificates
 that conform to the IETF PKIX profile SHOULD be indicated by the PKIX
 type, not the OID private type.  Recognition of private certificate
 types need not be based on OID equality but can use various forms of
 pattern matching such as OID prefix.

2.2. Text Representation of CERT RRs

 The RDATA portion of a CERT RR has the type field as an unsigned
 decimal integer or as a mnemonic symbol as listed in Section 2.1,
 above.
 The key tag field is represented as an unsigned decimal integer.
 The algorithm field is represented as an unsigned decimal integer or
 a mnemonic symbol as listed in [12].
 The certificate/CRL portion is represented in base 64 [16] and may be
 divided into any number of white-space-separated substrings, down to
 single base-64 digits, which are concatenated to obtain the full
 signature.  These substrings can span lines using the standard
 parenthesis.
 Note that the certificate/CRL portion may have internal sub-fields,
 but these do not appear in the master file representation.  For
 example, with type 254, there will be an OID size, an OID, and then
 the certificate/CRL proper.  However, only a single logical base-64
 string will appear in the text representation.

2.3. X.509 OIDs

 OIDs have been defined in connection with the X.500 directory for
 user certificates, certification authority certificates, revocations
 of certification authority, and revocations of user certificates.
 The following table lists the OIDs, their BER encoding, and their
 length-prefixed hex format for use in CERT RRs:

Josefsson Standards Track [Page 6] RFC 4398 Storing Certificates in the DNS February 2006

     id-at-userCertificate
         = { joint-iso-ccitt(2) ds(5) at(4) 36 }
            == 0x 03 55 04 24
     id-at-cACertificate
         = { joint-iso-ccitt(2) ds(5) at(4) 37 }
            == 0x 03 55 04 25
     id-at-authorityRevocationList
         = { joint-iso-ccitt(2) ds(5) at(4) 38 }
            == 0x 03 55 04 26
     id-at-certificateRevocationList
         = { joint-iso-ccitt(2) ds(5) at(4) 39 }
            == 0x 03 55 04 27

3. Appropriate Owner Names for CERT RRs

 It is recommended that certificate CERT RRs be stored under a domain
 name related to their subject, i.e., the name of the entity intended
 to control the private key corresponding to the public key being
 certified.  It is recommended that certificate revocation list CERT
 RRs be stored under a domain name related to their issuer.
 Following some of the guidelines below may result in DNS names with
 characters that require DNS quoting as per Section 5.1 of RFC 1035
 [2].
 The choice of name under which CERT RRs are stored is important to
 clients that perform CERT queries.  In some situations, the clients
 may not know all information about the CERT RR object it wishes to
 retrieve.  For example, a client may not know the subject name of an
 X.509 certificate, or the email address of the owner of an OpenPGP
 key.  Further, the client might only know the hostname of a service
 that uses X.509 certificates or the Key ID of an OpenPGP key.
 Therefore, two owner name guidelines are defined: content-based owner
 names and purpose-based owner names.  A content-based owner name is
 derived from the content of the CERT RR data; for example, the
 Subject field in an X.509 certificate or the User ID field in OpenPGP
 keys.  A purpose-based owner name is a name that a client retrieving
 CERT RRs ought to know already; for example, the host name of an
 X.509 protected service or the Key ID of an OpenPGP key.  The
 content-based and purpose-based owner name may be the same; for
 example, when a client looks up a key based on the From: address of
 an incoming email.
 Implementations SHOULD use the purpose-based owner name guidelines
 described in this document and MAY use CNAME RRs at content-based
 owner names (or other names), pointing to the purpose-based owner
 name.

Josefsson Standards Track [Page 7] RFC 4398 Storing Certificates in the DNS February 2006

 Note that this section describes an application-based mapping from
 the name space used in a certificate to the name space used by DNS.
 The DNS does not infer any relationship amongst CERT resource records
 based on similarities or differences of the DNS owner name(s) of CERT
 resource records.  For example, if multiple labels are used when
 mapping from a CERT identifier to a domain name, then care must be
 taken in understanding wildcard record synthesis.

3.1. Content-Based X.509 CERT RR Names

 Some X.509 versions, such as the PKIX profile of X.509 [8], permit
 multiple names to be associated with subjects and issuers under
 "Subject Alternative Name" and "Issuer Alternative Name".  For
 example, the PKIX profile has such Alternate Names with an ASN.1
 specification as follows:
    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 }
 The recommended locations of CERT storage are as follows, in priority
 order:
 1.  If a domain name is included in the identification in the
     certificate or CRL, that ought to be used.
 2.  If a domain name is not included but an IP address is included,
     then the translation of that IP address into the appropriate
     inverse domain name ought to be used.
 3.  If neither of the above is used, but a URI containing a domain
     name is present, that domain name ought to be used.
 4.  If none of the above is included but a character string name is
     included, then it ought to be treated as described below for
     OpenPGP names.
 5.  If none of the above apply, then the distinguished name (DN)
     ought to be mapped into a domain name as specified in [4].
 Example 1: An X.509v3 certificate is issued to /CN=John Doe /DC=Doe/
 DC=com/DC=xy/O=Doe Inc/C=XY/ with Subject Alternative Names of (a)
 string "John (the Man) Doe", (b) domain name john-doe.com, and (c)
 URI <https://www.secure.john-doe.com:8080/>.  The storage locations
 recommended, in priority order, would be

Josefsson Standards Track [Page 8] RFC 4398 Storing Certificates in the DNS February 2006

 1.  john-doe.com,
 2.  www.secure.john-doe.com, and
 3.  Doe.com.xy.
 Example 2: An X.509v3 certificate is issued to /CN=James Hacker/
 L=Basingstoke/O=Widget Inc/C=GB/ with Subject Alternate names of (a)
 domain name widget.foo.example, (b) IPv4 address 10.251.13.201, and
 (c) string "James Hacker <hacker@mail.widget.foo.example>".  The
 storage locations recommended, in priority order, would be
 1.  widget.foo.example,
 2.  201.13.251.10.in-addr.arpa, and
 3.  hacker.mail.widget.foo.example.

3.2. Purpose-Based X.509 CERT RR Names

 Due to the difficulty for clients that do not already possess a
 certificate to reconstruct the content-based owner name,
 purpose-based owner names are recommended in this section.
 Recommendations for purpose-based owner names vary per scenario.  The
 following table summarizes the purpose-based X.509 CERT RR owner name
 guidelines for use with S/MIME [17], SSL/TLS [13], and IPsec [14]:
  Scenario             Owner name
  ------------------   ----------------------------------------------
  S/MIME Certificate   Standard translation of an RFC 2822 email
                       address.  Example: An S/MIME certificate for
                       "postmaster@example.org" will use a standard
                       hostname translation of the owner name,
                       "postmaster.example.org".
  TLS Certificate      Hostname of the TLS server.
  IPsec Certificate    Hostname of the IPsec machine and/or, for IPv4
                       or IPv6 addresses, the fully qualified domain
                       name in the appropriate reverse domain.
 An alternate approach for IPsec is to store raw public keys [18].

3.3. Content-Based OpenPGP CERT RR Names

 OpenPGP signed keys (certificates) use a general character string
 User ID [5].  However, it is recommended by OpenPGP that such names
 include the RFC 2822 [7] email address of the party, as in "Leslie
 Example <Leslie@host.example>".  If such a format is used, the CERT
 ought to be under the standard translation of the email address into

Josefsson Standards Track [Page 9] RFC 4398 Storing Certificates in the DNS February 2006

 a domain name, which would be leslie.host.example in this case.  If
 no RFC 2822 name can be extracted from the string name, no specific
 domain name is recommended.
 If a user has more than one email address, the CNAME type can be used
 to reduce the amount of data stored in the DNS.  For example:
    $ORIGIN example.org.
    smith        IN CERT PGP 0 0 <OpenPGP binary>
    john.smith   IN CNAME smith
    js           IN CNAME smith

3.4. Purpose-Based OpenPGP CERT RR Names

 Applications that receive an OpenPGP packet containing encrypted or
 signed data but do not know the email address of the sender will have
 difficulties constructing the correct owner name and cannot use the
 content-based owner name guidelines.  However, these clients commonly
 know the key fingerprint or the Key ID.  The key ID is found in
 OpenPGP packets, and the key fingerprint is commonly found in
 auxiliary data that may be available.  In this case, use of an owner
 name identical to the key fingerprint and the key ID expressed in
 hexadecimal [16] is recommended.  For example:
    $ORIGIN example.org.
    0424D4EE81A0E3D119C6F835EDA21E94B565716F IN CERT PGP ...
    F835EDA21E94B565716F                     IN CERT PGP ...
    B565716F                                 IN CERT PGP ...
 If the same key material is stored for several owner names, the use
 of CNAME may help avoid data duplication.  Note that CNAME is not
 always applicable, because it maps one owner name to the other for
 all purposes, which may be sub-optimal when two keys with the same
 Key ID are stored.

3.5. Owner Names for IPKIX, ISPKI, IPGP, and IACPKIX

 These types are stored under the same owner names, both purpose- and
 content-based, as the PKIX, SPKI, PGP, and ACPKIX types.

Josefsson Standards Track [Page 10] RFC 4398 Storing Certificates in the DNS February 2006

4. Performance Considerations

 The Domain Name System (DNS) protocol was designed for small
 transfers, typically below 512 octets.  While larger transfers will
 perform correctly and work is underway to make larger transfers more
 efficient, it is still advisable at this time that every reasonable
 effort be made to minimize the size of certificates stored within the
 DNS.  Steps that can be taken may include using the fewest possible
 optional or extension fields and using short field values for
 necessary variable-length fields.
 The RDATA field in the DNS protocol may only hold data of size 65535
 octets (64kb) or less.  This means that each CERT RR MUST NOT contain
 more than 64kb of payload, even if the corresponding certificate or
 certificate revocation list is larger.  This document addresses this
 by defining "indirect" data types for each normal type.
 Deploying CERT RRs to support digitally signed email changes the
 access patterns of DNS lookups from per-domain to per-user.  If
 digitally signed email and a key/certificate lookup based on CERT RRs
 are deployed on a wide scale, this may lead to an increased DNS load,
 with potential performance and cache effectiveness consequences.
 Whether or not this load increase will be noticeable is not known.

5. Contributors

 The majority of this document is copied verbatim from RFC 2538, by
 Donald Eastlake 3rd and Olafur Gudmundsson.

6. Acknowledgements

 Thanks to David Shaw and Michael Graff for their contributions to
 earlier works that motivated, and served as inspiration for, this
 document.
 This document was improved by suggestions and comments from Olivier
 Dubuisson, Scott Hollenbeck, Russ Housley, Peter Koch, Olaf M.
 Kolkman, Ben Laurie, Edward Lewis, John Loughney, Allison Mankin,
 Douglas Otis, Marcos Sanz, Pekka Savola, Jason Sloderbeck, Samuel
 Weiler, and Florian Weimer.  No doubt the list is incomplete.  We
 apologize to anyone we left out.

Josefsson Standards Track [Page 11] RFC 4398 Storing Certificates in the DNS February 2006

7. Security Considerations

 By definition, certificates contain their own authenticating
 signatures.  Thus, it is reasonable to store certificates in
 non-secure DNS zones or to retrieve certificates from DNS with DNS
 security checking not implemented or deferred for efficiency.  The
 results may be trusted if the certificate chain is verified back to a
 known trusted key and this conforms with the user's security policy.
 Alternatively, if certificates are retrieved from a secure DNS zone
 with DNS security checking enabled and are verified by DNS security,
 the key within the retrieved certificate may be trusted without
 verifying the certificate chain if this conforms with the user's
 security policy.
 If an organization chooses to issue certificates for its employees,
 placing CERT RRs in the DNS by owner name, and if DNSSEC (with NSEC)
 is in use, it is possible for someone to enumerate all employees of
 the organization.  This is usually not considered desirable, for the
 same reason that enterprise phone listings are not often publicly
 published and are even marked confidential.
 Using the URI type introduces another level of indirection that may
 open a new vulnerability.  One method of securing that indirection is
 to include a hash of the certificate in the URI itself.
 If DNSSEC is used, then the non-existence of a CERT RR and,
 consequently, certificates or revocation lists can be securely
 asserted.  Without DNSSEC, this is not possible.

8. IANA Considerations

 The IANA has created a new registry for CERT RR: certificate types.
 The initial contents of this registry is:
     Decimal   Type     Meaning                           Reference
     -------   ----     -------                           ---------
           0            Reserved                          RFC 4398
           1   PKIX     X.509 as per PKIX                 RFC 4398
           2   SPKI     SPKI certificate                  RFC 4398
           3   PGP      OpenPGP packet                    RFC 4398
           4   IPKIX    The URL of an X.509 data object   RFC 4398
           5   ISPKI    The URL of an SPKI certificate    RFC 4398
           6   IPGP     The fingerprint and URL           RFC 4398
                        of an OpenPGP packet
           7   ACPKIX   Attribute Certificate             RFC 4398
           8   IACPKIX  The URL of an Attribute           RFC 4398
                           Certificate

Josefsson Standards Track [Page 12] RFC 4398 Storing Certificates in the DNS February 2006

       9-252            Available for IANA assignment
                           by IETF Standards action
         253   URI      URI private                       RFC 4398
         254   OID      OID private                       RFC 4398
         255            Reserved                          RFC 4398
   256-65279            Available for IANA assignment
                        by IETF Consensus
 65280-65534            Experimental                      RFC 4398
       65535            Reserved                          RFC 4398
 Certificate types 0x0000 through 0x00FF and 0xFF00 through 0xFFFF can
 only be assigned by an IETF standards action [6].  This document
 assigns 0x0001 through 0x0008 and 0x00FD and 0x00FE.  Certificate
 types 0x0100 through 0xFEFF are assigned through IETF Consensus [6]
 based on RFC documentation of the certificate type.  The availability
 of private types under 0x00FD and 0x00FE ought to satisfy most
 requirements for proprietary or private types.
 The CERT RR reuses the DNS Security Algorithm Numbers registry.  In
 particular, the CERT RR requires that algorithm number 0 remain
 reserved, as described in Section 2.  The IANA will reference the
 CERT RR as a user of this registry and value 0, in particular.

9. Changes since RFC 2538

 1.   Editorial changes to conform with new document requirements,
      including splitting reference section into two parts and
      updating the references to point at latest versions, and to add
      some additional references.
 2.   Improve terminology.  For example replace "PGP" with "OpenPGP",
      to align with RFC 2440.
 3.   In Section 2.1, clarify that OpenPGP public key data are binary,
      not the ASCII armored format, and reference 10.1 in RFC 2440 on
      how to deal with OpenPGP keys, and acknowledge that
      implementations may handle additional packet types.
 4.   Clarify that integers in the representation format are decimal.
 5.   Replace KEY/SIG with DNSKEY/RRSIG etc, to align with DNSSECbis
      terminology.  Improve reference for Key Tag Algorithm
      calculations.
 6.   Add examples that suggest use of CNAME to reduce bandwidth.
 7.   In Section 3, appended the last paragraphs that discuss
      "content-based" vs "purpose-based" owner names.  Add Section 3.2
      for purpose-based X.509 CERT owner names, and Section 3.4 for
      purpose-based OpenPGP CERT owner names.
 8.   Added size considerations.
 9.   The SPKI types has been reserved, until RFC 2692/2693 is moved
      from the experimental status.
 10.  Added indirect types IPKIX, ISPKI, IPGP, and IACPKIX.

Josefsson Standards Track [Page 13] RFC 4398 Storing Certificates in the DNS February 2006

 11.  An IANA registry of CERT type values was created.

10. References

10.1. Normative References

 [1]   Mockapetris, P., "Domain names - concepts and facilities",
       STD 13, RFC 1034, November 1987.
 [2]   Mockapetris, P., "Domain names - implementation and
       specification", STD 13, RFC 1035, November 1987.
 [3]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
       Levels", BCP 14, RFC 2119, March 1997.
 [4]   Kille, S., Wahl, M., Grimstad, A., Huber, R., and S. Sataluri,
       "Using Domains in LDAP/X.500 Distinguished Names", RFC 2247,
       January 1998.
 [5]   Callas, J., Donnerhacke, L., Finney, H., and R. Thayer,
       "OpenPGP Message Format", RFC 2440, November 1998.
 [6]   Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
       Considerations Section in RFCs", BCP 26, RFC 2434,
       October 1998.
 [7]   Resnick, P., "Internet Message Format", RFC 2822, April 2001.
 [8]   Housley, R., Polk, W., Ford, W., and D. Solo, "Internet X.509
       Public Key Infrastructure Certificate and Certificate
       Revocation List (CRL) Profile", RFC 3280, April 2002.
 [9]   Farrell, S. and R. Housley, "An Internet Attribute Certificate
       Profile for Authorization", RFC 3281, April 2002.
 [10]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
       Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
       January 2005.
 [11]  Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
       "DNS Security Introduction and Requirements", RFC 4033,
       March 2005.
 [12]  Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
       "Resource Records for the DNS Security Extensions", RFC 4034,
       March 2005.

Josefsson Standards Track [Page 14] RFC 4398 Storing Certificates in the DNS February 2006

10.2. Informative References

 [13]  Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
       RFC 2246, January 1999.
 [14]  Kent, S. and K. Seo, "Security Architecture for the Internet
       Protocol", RFC 4301, December 2005.
 [15]  Ellison, C., Frantz, B., Lampson, B., Rivest, R., Thomas, B.,
       and T. Ylonen, "SPKI Certificate Theory", RFC 2693,
       September 1999.
 [16]  Josefsson, S., "The Base16, Base32, and Base64 Data Encodings",
       RFC 3548, July 2003.
 [17]  Ramsdell, B., "Secure/Multipurpose Internet Mail Extensions
       (S/MIME) Version 3.1 Message Specification", RFC 3851,
       July 2004.
 [18]  Richardson, M., "A Method for Storing IPsec Keying Material in
       DNS", RFC 4025, March 2005.

Josefsson Standards Track [Page 15] RFC 4398 Storing Certificates in the DNS February 2006

Appendix A. Copying Conditions

 Regarding the portion of this document that was written by Simon
 Josefsson ("the author", for the remainder of this section), the
 author makes no guarantees and is not responsible for any damage
 resulting from its use.  The author grants irrevocable permission to
 anyone to use, modify, and distribute it in any way that does not
 diminish the rights of anyone else to use, modify, and distribute it,
 provided that redistributed derivative works do not contain
 misleading author or version information.  Derivative works need not
 be licensed under similar terms.

Author's Address

 Simon Josefsson
 EMail: simon@josefsson.org

Josefsson Standards Track [Page 16] RFC 4398 Storing Certificates in the DNS February 2006

Full Copyright Statement

 Copyright (C) The Internet Society (2006).
 This document is subject to the rights, licenses and restrictions
 contained in BCP 78, and except as set forth therein, the authors
 retain all their rights.
 This document and the information contained herein are provided on an
 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
 ENGINEERING TASK FORCE DISCLAIM 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.

Intellectual Property

 The IETF takes no position regarding the validity or scope of any
 Intellectual Property Rights 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; nor does it represent that it has
 made any independent effort to identify any such rights.  Information
 on the procedures with respect to rights in RFC documents can be
 found in BCP 78 and BCP 79.
 Copies of IPR disclosures made to the IETF Secretariat and any
 assurances of licenses to be made available, or the result of an
 attempt made to obtain a general license or permission for the use of
 such proprietary rights by implementers or users of this
 specification can be obtained from the IETF on-line IPR repository at
 http://www.ietf.org/ipr.
 The IETF invites any interested party to bring to its attention any
 copyrights, patents or patent applications, or other proprietary
 rights that may cover technology that may be required to implement
 this standard.  Please address the information to the IETF at
 ietf-ipr@ietf.org.

Acknowledgement

 Funding for the RFC Editor function is provided by the IETF
 Administrative Support Activity (IASA).

Josefsson Standards Track [Page 17]

/data/webs/external/dokuwiki/data/pages/rfc/rfc4398.txt · Last modified: 2006/03/30 17:52 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki