GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc6253

Internet Engineering Task Force (IETF) T. Heer Request for Comments: 6253 COMSYS, RWTH Aachen University Updates: 5201 S. Varjonen Category: Experimental Helsinki Institute for Information Technology ISSN: 2070-1721 May 2011

                Host Identity Protocol Certificates

Abstract

 The Certificate (CERT) parameter is a container for digital
 certificates.  It is used for carrying these certificates in Host
 Identity Protocol (HIP) control packets.  This document specifies the
 CERT parameter and the error signaling in case of a failed
 verification.  Additionally, this document specifies the
 representations of Host Identity Tags in X.509 version 3 (v3) and
 Simple Public Key Infrastructure (SPKI) certificates.
 The concrete use of certificates, including how certificates are
 obtained, requested, and which actions are taken upon successful or
 failed verification, is specific to the scenario in which the
 certificates are used.  Hence, the definition of these scenario-
 specific aspects is left to the documents that use the CERT
 parameter.
 This document updates RFC 5201.

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for examination, experimental implementation, and
 evaluation.
 This document defines an Experimental Protocol for the Internet
 community.  This document is a product of the Internet Engineering
 Task Force (IETF).  It represents the consensus of the IETF
 community.  It has received public review and has been approved for
 publication by the Internet Engineering Steering Group (IESG).  Not
 all documents approved by the IESG are a candidate for any level of
 Internet Standard; see Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6253.

Heer & Varjonen Experimental [Page 1] RFC 6253 HIP CERT May 2011

Copyright Notice

 Copyright (c) 2011 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified
 outside the IETF Standards Process, and derivative works of it may
 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

1. Introduction

 Digital certificates bind pieces of information to a public key by
 means of a digital signature and thus enable the holder of a private
 key to generate cryptographically verifiable statements.  The Host
 Identity Protocol (HIP) [RFC5201] defines a new cryptographic
 namespace based on asymmetric cryptography.  The identity of each
 host is derived from a public key, allowing hosts to digitally sign
 data and issue certificates with their private key.  This document
 specifies the CERT parameter, which is used to transmit digital
 certificates in HIP.  It fills the placeholder specified in
 Section 5.2 of [RFC5201] and thus updates [RFC5201].

1.1. Requirements Language

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
 "OPTIONAL" in this document are to be interpreted as described in
 RFC 2119 [RFC2119].

Heer & Varjonen Experimental [Page 2] RFC 6253 HIP CERT May 2011

2. CERT Parameter

 The CERT parameter is a container for certain types of digital
 certificates.  It does not specify any certificate semantics.
 However, it defines supplementary parameters that help HIP hosts to
 transmit semantically grouped CERT parameters in a more systematic
 way.  The specific use of the CERT parameter for different use cases
 is intentionally not discussed in this document, because it is
 specific to a concrete use case.  Hence, the use of the CERT
 parameter will be defined in the documents that use the CERT
 parameter.
 The CERT parameter is covered and protected, when present, by the HIP
 SIGNATURE field and is a non-critical parameter.
 The CERT parameter can be used in all HIP packets.  However, using it
 in the first Initiator (I1) packet is NOT RECOMMENDED, because it can
 increase the processing times of I1s, which can be problematic when
 processing storms of I1s.  Each HIP control packet MAY contain
 multiple CERT parameters.  These parameters MAY be related or
 unrelated.  Related certificates are managed in Cert groups.  A Cert
 group specifies a group of related CERT parameters that SHOULD be
 interpreted in a certain order (e.g., for expressing certificate
 chains).  For grouping CERT parameters, the Cert group and the Cert
 count field MUST be set.  Ungrouped certificates exhibit a unique
 Cert group field and set the Cert count to 1.  CERT parameters with
 the same Cert group number in the group field indicate a logical
 grouping.  The Cert count field indicates the number of CERT
 parameters in the group.
 CERT parameters that belong to the same Cert group MAY be contained
 in multiple sequential HIP control packets.  This is indicated by a
 higher Cert count than the amount of CERT parameters with matching
 Cert group fields in a HIP control packet.  The CERT parameters MUST
 be placed in ascending order, within a HIP control packet, according
 to their Cert group field.  Cert groups MAY only span multiple
 packets if the Cert group does not fit the packet.  A HIP packet MUST
 NOT contain more than one incomplete Cert group that continues in the
 next HIP control packet.
 The Cert ID acts as a sequence number to identify the certificates in
 a Cert group.  The numbers in the Cert ID field MUST start from 1 up
 to Cert count.
 The Cert group and Cert ID namespaces are managed locally by each
 host that sends CERT parameters in HIP control packets.

Heer & Varjonen Experimental [Page 3] RFC 6253 HIP CERT May 2011

   0                   1                   2                   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              |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Cert group   |  Cert count   |    Cert ID    |   Cert type   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Certificate                          /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                               |            Padding            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  Type          768
  Length        Length in octets, excluding Type, Length, and Padding.
  Cert group    Group ID grouping multiple related CERT parameters.
  Cert count    Total count of certificates that are sent, possibly
                in several consecutive HIP control packets.
  Cert ID       The sequence number for this certificate.
  Cert Type     Indicates the type of the certificate.
  Padding       Any Padding, if necessary, to make the TLV a multiple
                of 8 bytes.
 The certificates MUST use the algorithms defined in [RFC5201] as the
 signature and hash algorithms.
 The following certificate types are defined:
           +--------------------------------+-------------+
           |           Cert format          | Type number |
           +--------------------------------+-------------+
           |            Reserved            |      0      |
           |            X.509 v3            |      1      |
           |              SPKI              |      2      |
           |    Hash and URL of X.509 v3    |      3      |
           |      Hash and URL of SPKI      |      4      |
           |      LDAP URL of X.509 v3      |      5      |
           |        LDAP URL of SPKI        |      6      |
           | Distinguished Name of X.509 v3 |      7      |
           |   Distinguished Name of SPKI   |      8      |
           +--------------------------------+-------------+
 The next sections outline the use of Host Identity Tags (HITs) in
 X.509 v3 and in Simple Public Key Infrastructure (SPKI) certificates.
 X.509 v3 certificates and the handling procedures are defined in
 [RFC5280].  The wire format for X.509 v3 is the Distinguished
 Encoding Rules format as defined in [X.690].  The SPKI, the handling
 procedures, and the formats are defined in [RFC2693].

Heer & Varjonen Experimental [Page 4] RFC 6253 HIP CERT May 2011

 Hash and Uniform Resource Locator (URL) encodings (3 and 4) are used
 as defined in Section 3.6 of [RFC5996].  Using hash and URL encodings
 results in smaller HIP control packets than by including the
 certificate(s), but requires the receiver to resolve the URL or check
 a local cache against the hash.
 Lightweight Directory Access Protocol (LDAP) URL encodings (5 and 6)
 are used as defined in [RFC4516].  Using LDAP URL encoding results in
 smaller HIP control packets but requires the receiver to retrieve the
 certificate or check a local cache against the URL.
 Distinguished Name (DN) encodings (7 and 8) are represented by the
 string representation of the certificate's subject DN as defined in
 [RFC4514].  Using the DN encoding results in smaller HIP control
 packets, but requires the receiver to retrieve the certificate or
 check a local cache against the DN.

3. X.509 v3 Certificate Object and Host Identities

 If needed, HITs can represent an issuer, a subject, or both in
 X.509 v3.  HITs are represented as IPv6 addresses as defined in
 [RFC4843].  When the Host Identifier (HI) is used to sign the
 certificate, the respective HIT MUST be placed into the Issuer
 Alternative Name (IAN) extension using the GeneralName form iPAddress
 as defined in [RFC5280].  When the certificate is issued for a HIP
 host, identified by a HIT and HI, the respective HIT MUST be placed
 into the Subject Alternative Name (SAN) extension using the
 GeneralName form iPAddress, and the full HI is presented as the
 subject's public key info as defined in [RFC5280].
 The following examples illustrate how HITs are presented as issuer
 and subject in the X.509 v3 extension alternative names.
     Format of X509v3 extensions:
         X509v3 Issuer Alternative Name:
             IP Address:hit-of-issuer
         X509v3 Subject Alternative Name:
             IP Address:hit-of-subject
     Example X509v3 extensions:
         X509v3 Issuer Alternative Name:
             IP Address:2001:14:6cf:fae7:bb79:bf78:7d64:c056
         X509v3 Subject Alternative Name:
             IP Address:2001:1c:5a14:26de:a07c:385b:de35:60e3
 Appendix B shows a full example of an X.509 v3 certificate with HIP
 content.

Heer & Varjonen Experimental [Page 5] RFC 6253 HIP CERT May 2011

 As another example, consider a managed Public Key Infrastructure
 (PKI) environment in which the peers have certificates that are
 anchored in (potentially different) managed trust chains.  In this
 scenario, the certificates issued to HIP hosts are signed by
 intermediate Certification Authorities (CAs) up to a root CA.  In
 this example, the managed PKI environment is neither HIP aware, nor
 can it be configured to compute HITs and include them in the
 certificates.
 When HIP communications are established, the HIP hosts not only need
 to send their identity certificates (or pointers to their
 certificates), but also the chain of intermediate CAs (or pointers to
 the CAs) up to the root CA, or to a CA that is trusted by the remote
 peer.  This chain of certificates MUST be sent in a Cert group as
 specified in Section 2.  The HIP peers validate each other's
 certificates and compute peer HITs based on the certificate public
 keys.

4. SPKI Cert Object and Host Identities

 When using SPKI certificates to transmit information related to HIP
 hosts, HITs need to be enclosed within the certificates.  HITs can
 represent an issuer, a subject, or both.  In the following, we define
 the representation of those identifiers for SPKI given as
 S-expressions.  Note that the S-expressions are only the human-
 readable representation of SPKI certificates.  Full HIs are presented
 in the public key sequences of SPKI certificates.
 As an example, the Host Identity Tag of a host is expressed as
 follows:
     Format:  (hash hit hit-of-host)
     Example: (hash hit 2001:13:724d:f3c0:6ff0:33c2:15d8:5f50)
 Appendix A shows a full example of a SPKI certificate with HIP
 content.

5. Revocation of Certificates

 Revocation of X.509 v3 certificates is handled as defined in
 Section 5 of [RFC5280].  Revocation of SPKI certificates is handled
 as defined in Section 5 of [RFC2693].

Heer & Varjonen Experimental [Page 6] RFC 6253 HIP CERT May 2011

6. Error Signaling

 If the Initiator does not send the certificate that the Responder
 requires, the Responder may take actions (e.g., reject the
 connection).  The Responder MAY signal this to the Initiator by
 sending a HIP NOTIFY message with NOTIFICATION parameter error type
 CREDENTIALS_REQUIRED.
 If the verification of a certificate fails, a verifier MAY signal
 this to the provider of the certificate by sending a HIP NOTIFY
 message with NOTIFICATION parameter error type INVALID_CERTIFICATE.
   NOTIFICATION PARAMETER - ERROR TYPES     Value
   ------------------------------------     -----
   CREDENTIALS_REQUIRED                      48
   The Responder is unwilling to set up an association,
   as the Initiator did not send the needed credentials.
   INVALID_CERTIFICATE                       50
   Sent in response to a failed verification of a certificate.
   Notification Data MAY contain n groups of 2 octets (n calculated
   from the NOTIFICATION parameter length), in order Cert group and
   Cert ID of the Certificate parameter that caused the failure.

7. IANA Considerations

 This document defines the CERT parameter for the Host Identity
 Protocol [RFC5201].  This parameter is defined in Section 2 with type
 768.  The parameter type number is also defined in [RFC5201].
 The CERT parameter has an 8-bit unsigned integer field for different
 certificate types, for which IANA has created and now maintains a new
 sub-registry entitled "HIP Certificate Types" under the "Host
 Identity Protocol (HIP) Parameters".  Initial values for the
 Certificate type registry are given in Section 2.  New values for the
 Certificate types from the unassigned space are assigned through IETF
 Review.
 In Section 6, this document defines two new types for the "NOTIFY
 Message Types" sub-registry under "Host Identity Protocol (HIP)
 Parameters".

Heer & Varjonen Experimental [Page 7] RFC 6253 HIP CERT May 2011

8. Security Considerations

 Certificate grouping allows the certificates to be sent in multiple
 consecutive packets.  This might allow similar attacks, as IP-layer
 fragmentation allows, for example, the sending of fragments in the
 wrong order and skipping some fragments to delay or stall packet
 processing by the victim in order to use resources (e.g., CPU or
 memory).  Hence, hosts SHOULD implement mechanisms to discard
 certificate groups with outstanding certificates if state space is
 scarce.
 Checking of the URL and LDAP entries might allow denial-of-service
 (DoS) attacks, where the target host may be subjected to bogus work.
 Security considerations for SPKI certificates are discussed in
 [RFC2693] and for X.509 v3 in [RFC5280].

9. Acknowledgements

 The authors would like to thank A. Keranen, D. Mattes, M. Komu, and
 T. Henderson for the fruitful conversations on the subject.  D.
 Mattes most notably contributed the non-HIP aware use case in
 Section 3.

10. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2693]  Ellison, C., Frantz, B., Lampson, B., Rivest, R., Thomas,
            B., and T. Ylonen, "SPKI Certificate Theory", RFC 2693,
            September 1999.
 [RFC4514]  Zeilenga, K., Ed., "Lightweight Directory Access Protocol
            (LDAP): String Representation of Distinguished Names",
            RFC 4514, June 2006.
 [RFC4516]  Smith, M., Ed., and T. Howes, "Lightweight Directory
            Access Protocol (LDAP): Uniform Resource Locator",
            RFC 4516, June 2006.
 [RFC4843]  Nikander, P., Laganier, J., and F. Dupont, "An IPv6 Prefix
            for Overlay Routable Cryptographic Hash Identifiers
            (ORCHID)", RFC 4843, April 2007.
 [RFC5201]  Moskowitz, R., Nikander, P., Jokela, P., Ed., and T.
            Henderson, "Host Identity Protocol", RFC 5201, April 2008.

Heer & Varjonen Experimental [Page 8] RFC 6253 HIP CERT May 2011

 [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
            Housley, R., and W. Polk, "Internet X.509 Public Key
            Infrastructure Certificate and Certificate Revocation List
            (CRL) Profile", RFC 5280, May 2008.
 [RFC5996]  Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
            "Internet Key Exchange Protocol Version 2 (IKEv2)",
            RFC 5996, September 2010.
 [X.690]    ITU-T, "Recommendation X.690 (2002) | ISO/IEC 8825-1:2002,
            Information Technology - ASN.1 encoding rules:
            Specification of Basic Encoding Rules (BER), Canonical
            Encoding Rules (CER) and Distinguished Encoding Rules
            (DER)", July 2002.

Heer & Varjonen Experimental [Page 9] RFC 6253 HIP CERT May 2011

Appendix A. SPKI Certificate Example

 This section shows an SPKI certificate with encoded HITs.  The
 example has been indented for readability.
 (sequence
   (public_key
     (rsa-pkcs1-sha1
       (e #010001#)
       (n |yDwznOwX0w+zvQbpWoTnfWrUPLKW2NFrpXbsIcH/QBSLb
           k1RKTZhLasFwvtSHAjqh220W8gRiQAGIqKplyrDEqSrJp
           OdIsHIQ8BQhJAyILWA1Sa6f5wAnWozDfgdXoKLNdT8ZNB
           mzluPiw4ozc78p6MHElH75Hm3yHaWxT+s83M=|
       )
       )
     )
     (cert
       (issuer
         (hash hit 2001:15:2453:698a:9aa:253a:dcb5:981e)
       )
       (subject
         (hash hit 2001:12:ccd6:4715:72a3:2ab1:77e4:4acc)
       )
       (not-before "2011-01-12_13:43:09")
       (not-after "2011-01-22_13:43:09")
     )
     (signature
       (hash sha1 |h5fC8HUMATTtK0cjYqIgeN3HCIMA|)
       |u8NTRutINI/AeeZgN6bngjvjYPtVahvY7MhGfenTpT7MCgBy
       NoZglqH5Cy2vH6LrQFYWx0MjWoYwHKimEuBKCNd4TK6hrCyAI
       CIDJAZ70TyKXgONwDNWPOmcc3lFmsih8ezkoBseFWHqRGISIm
       MLdeaMciP4lVfxPY2AQKdMrBc=|
   )
 )

Heer & Varjonen Experimental [Page 10] RFC 6253 HIP CERT May 2011

Appendix B. X.509 v3 Certificate Example

 This section shows a X.509 v3 certificate with encoded HITs.
 Certificate:
     Data:
         Version: 3 (0x2)
         Serial Number: 0 (0x0)
         Signature Algorithm: sha1WithRSAEncryption
         Issuer: CN=Example issuing host, DC=example, DC=com
         Validity
             Not Before: Mar 11 09:01:39 2011 GMT
             Not After : Mar 21 09:01:39 2011 GMT
         Subject: CN=Example subject host, DC=example, DC=com
         Subject Public Key Info:
             Public Key Algorithm: rsaEncryption
             RSA Public Key: (1024 bit)
                 Modulus (1024 bit):
                     00:c0:db:38:50:8e:63:ed:96:ea:c6:c4:ec:a3:36:
                     62:e2:28:e9:74:9c:f5:2f:cb:58:0e:52:54:60:b5:
                     fa:98:87:0d:22:ab:d8:6a:61:74:a9:ee:0b:ae:cd:
                     18:6f:05:ab:69:66:42:46:00:a2:c0:0c:3a:28:67:
                     09:cc:52:27:da:79:3e:67:d7:d8:d0:7c:f1:a1:26:
                     fa:38:8f:73:f5:b0:20:c6:f2:0b:7d:77:43:aa:c7:
                     98:91:7e:1e:04:31:0d:ca:94:55:20:c4:4f:ba:b1:
                     df:d4:61:9d:dd:b9:b5:47:94:6c:06:91:69:30:42:
                     9c:0a:8b:e3:00:ce:49:ab:e3
                 Exponent: 65537 (0x10001)
         X509v3 extensions:
             X509v3 Issuer Alternative Name:
                 IP Address:2001:13:8d83:41c5:dc9f:38ed:e742:7281
             X509v3 Subject Alternative Name:
                 IP Address:2001:1c:6e02:d3e0:9b90:8417:673e:99db
     Signature Algorithm: sha1WithRSAEncryption
         83:68:b4:38:63:a6:ae:57:68:e2:4d:73:5d:8f:11:e4:ba:30:
         a0:19:ca:86:22:e9:6b:e9:36:96:af:95:bd:e8:02:b9:72:2f:
         30:a2:62:ac:b2:fa:3d:25:c5:24:fd:8d:32:aa:01:4f:a5:8a:
         f5:06:52:56:0a:86:55:39:2b:ee:7a:7b:46:14:d7:5d:15:82:
         4d:74:06:ca:b7:8c:54:c1:6b:33:7f:77:82:d8:95:e1:05:ca:
         e2:0d:22:1d:86:fc:1c:c4:a4:cf:c6:bc:ab:ec:b8:2a:1e:4b:
         04:7e:49:9c:8f:9d:98:58:9c:63:c5:97:b5:41:94:f7:ef:93:
         57:29

Heer & Varjonen Experimental [Page 11] RFC 6253 HIP CERT May 2011

Authors' Addresses

 Tobias Heer
 Chair of Communication and Distributed Systems - COMSYS
 RWTH Aachen University
 Ahornstrasse 55
 Aachen
 Germany
 Phone: +49 241 80 20 776
 EMail: heer@cs.rwth-aachen.de
 URI:   http://www.comsys.rwth-aachen.de/team/tobias-heer/
 Samu Varjonen
 Helsinki Institute for Information Technology
 Gustaf Haellstroemin katu 2b
 Helsinki
 Finland
 EMail: samu.varjonen@hiit.fi
 URI:   http://www.hiit.fi

Heer & Varjonen Experimental [Page 12]

/data/webs/external/dokuwiki/data/pages/rfc/rfc6253.txt · Last modified: 2011/05/26 16:32 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki