Secure Inter-Domain Routing Working Group                      S. Turner
Internet-Draft                                                      IECA
Updates: 6485 (if approved)                               March 26, 2013
Intended Status: Standards Track
Expires: September 27, 2013

            BGP Algorithms, Key Formats, & Signature Formats
                     draft-ietf-sidr-bgpsec-algs-04

Abstract

   This document specifies the algorithms, algorithms' parameters,
   asymmetric key formats, asymmetric key size and signature format used
   in BGPSEC (Border Gateway Protocol Security).  This document updates
   the Profile for Algorithms and Key Sizes for use in the Resource
   Public Key Infrastructure (RFC 6485).

Status of this Memo

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.  Introduction

   This document specifies:
      o the digital signature algorithm and parameters;
      o the hash algorithm and parameters;
      o the public and private key formats; and,
      o the signature format
   used by Resource Public Key Infrastructure (RPKI) Certification
   Authorities (CA), and BGPSEC (Border Gateway Protocol Security)
   speakers (i.e., routers).  CAs use these algorithms when issuing
   BGPSEC Router Certificates [ID.bgpsec-pki-profiles] and CRLs
   [RFC6487].  BGPSEC routers use these when requesting BGPSEC
   certificates [ID.bgpsec-pki-profiles], generating BGPSEC Update
   messages [ID.sidr-bgpsec-protocol], and verifying BGPSEC Update
   messages [ID.sidr-bgpsec-protocol].

   This document is referenced by the BGPSEC specification [ID.bgpsec-
   protocol] and the profile for BGPSEC Router Certificates and
   Certification Requests [ID.bgpsec-pki-profiles].  Familiarity with
   these documents is assumed.  Implementers are reminded, however,
   that, as noted in Section 2 of [ID.bgpsec-pki-profiles], the
   algorithms used to sign CA Certificates, BGPSEC Router Certificates,
   and CRLs are found in [RFC6485].

   This document updates [RFC6485] to add support for a) a different
   algorithm for BGPSEC certificate requests, which are only issued by
   BGPSEC speakers; b) a different Subject Public Key Info format for
   BGPSEC certificates, which is needed for the specified BGPSEC
   signature algorithm; and, c) a different signature format for BGPSEC
   signatures, which is needed for the specified BGPSEC signature
   algorithm.  The BGPSEC certificate are differentiated from other RPKI
   certificates by the use of the BGPSEC Extended Key Usage defined in
   [ID.bgpsec-pki-profiles].

1.1.  Terminology

   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
   [RFC2119].

.  Algorithms

   Four cryptographic algorithms are used to support BGPSEC:

     o The signature algorithm used when issuing BGPSEC certificates and
       CRLs, which would revoke BGPSEC certificates, MUST be as
       specified in [RFC6485].



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     o The signature algorithm used in certification requests and BGPSEC
       Update messages MUST be Elliptic Curve Digital Signature
       Algorithm (ECDSA) [RFC6090].

     o The hashing algorithm used when issuing certificates and CRLs
       MUST be as specified in [RFC6485].

     o The hashing algorithm use when generating certification requests
       and BGPSEC Update messages MUST be SHA-256 [SHS].  Hash
       algorithms are not identified by themselves in certificates, or
       BGPSEC Update messages instead they are combined with the digital
       signature algorithm (see below).

       NOTE: The exception to the above hashing algorithm is the use of
       SHA-1 [SHS] when CAs generate authority and subject key
       identifiers [ID.bgpsec-pki-profiles].

   To support BGPSEC, the algorithms are identified as follows:

     o In certificates and CRLs, an Object Identifier (OID) is used.
       The value and locations are as specified in section 2 of
       [RFC6485].

     o In certification request, an OID is used.  The ecdsa-with-SHA256
       OID [RFC5480] MUST appear in the PKCS #10 signatureAlgorithm
       field [RFC4211] or in Certificate Request Message Format (CRMF)
       POPOSigningKey signature field [RFC2986].

     o In BGPSEC Update messages, the ECDSA with SHA-256 Algorithm Suite
       Identifier from Section 7 is included in the Signature-Block
       List's Algorithm Suite Identifier field.

.  Asymmetric Key Format

   The RSA key pairs used to compute signatures on CA certificates,
   BGPSEC Router Certificates, and CRLs are as specified in section 3 of
   [RFC6485].  The remainder of this section addresses key formats found
   in the BGPSEC router certificate requests and in BGPSEC Router
   Certificates.

   The ECDSA key pairs used to compute signatures for certificate
   requests and BGPSEC Update messages MUST come from the P-256 curve
   [RFC5480].  The public key pair MUST use the uncompressed form.

3.1.  Public Key Format

   The Subject's public key is included in subjectPublicKeyInfo
   [RFC5280].  It has two sub-fields: algorithm and subjectPublicKey.



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   The values for the structures and their sub-structures follow:

     o algorithm (which is an AlgorithmIdentifier type):  The id-
       ecPublicKey OID MUST be used in the algorithm field, as specified
       in 2.1.1 of [RFC5480].  The value for the associated parameters
       MUST be secp256r1, as specified in 2.1.1.1 of [RFC5480].

     o subjectPublicKey:  ECPublicKey MUST be used to encode the
       certificate's subjectPublicKey field, as specified in Section 2.2
       of [RFC5480].

3.2.  Private Key Format

   Local Policy determines private key format.

.  Signature Format

   The structure for the certificate's and CRL's signature field MUST be
   as specified in Section 4 of [RFC6485].  The structure for the
   certification request's and BGPSEC Update message's signature field
   MUST be as specified in Section 2.2.3 of [RFC3279].

.  Additional Requirements

   It is anticipated that BGPSEC will require the adoption of updated
   key sizes and a different set of signature and hash algorithms over
   time, in order to maintain an acceptable level of cryptographic
   security to protect the integrity of BGPSEC. This profile should be
   updated to specify such future requirements, when appropriate.

   CAs and RPs SHOULD be capable of supporting a transition to allow for
   the phased introduction of additional encryption algorithms and key
   specifications, and also accommodate the orderly deprecation of
   previously specified algorithms and keys.  Accordingly, CAs and RPs
   SHOULD be capable of supporting multiple RPKI algorithm and key
   profiles simultaneously within the scope of such anticipated
   transitions.  The recommended procedures to implement such a
   transition of key sizes and algorithms is not specified in this
   document.

.  Security Considerations

   The Security Considerations of [RFC3279], [RFC5480], [RFC6090],
   [RFC6485], and [ID.bgpsec-pki-profiles] apply to certificates.  The
   security considerations of [RFC3279], [RFC6090], [RFC6485],
   [ID.bgpsec-pki-profiles] apply to certification requests.  The
   security considerations of [RFC3279], [ID.sidr-bgpsec-protocol], and
   [RFC6090] apply to BGPSEC Update messages.  No new security are



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   introduced as a result of this specification.

.  IANA Considerations

   The Internet Assigned Numbers Authority (IANA) is requested to define
   the "BGPSEC Algorithm Suite Registry" described below.

   An algorithm suite consists of a digest algorithm and a signature
   algorithm.  This specification creates an IANA registry of one-octet
   BGPSEC algorithm suite identifiers.  Additionally, this document
   registers a single algorithm suite which uses the digest algorithm
   SHA-256 and the signature algorithm ECDSA on the P-256 curve
   [RFC5480].

                     BGPSEC Algorithm Suites Registry

          Digest        Signature     Algorithm Suite    Specification
         Algorithm      Algorithm       Identifier          Pointer
    +----------------------------------------------------------------+
    |   SHA-256   |   ECDSA P-256   |       TBD       |   RFC 5480   |
    +----------------------------------------------------------------+

   Future assignments are to be made using either the Standards Action
   process defined in [RFC5226], or the Early IANA Allocation process
   defined in [RFC4020].  Assignments consist of a digest algorithm
   name, signature algorithm name, and the algorithm suite identifier
   value.

.  Acknowledgements

   The author wishes to thank Geoff Huston for producing [RFC6485],
   which this document is heavily based on.  I'd also like to thank
   Roque Gagliano for his review and comments.

.  References

11.1.  Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2986] Nystrom, M. and B. Kaliski, "PKCS #10: Certification
             Request Syntax Specification Version 1.7", RFC 2986,
             November 2000.

   [RFC3279] Bassham, L., Polk, W., and R. Housley, "Algorithms and
             Identifiers for the Internet X.509 Public Key
             Infrastructure Certificate and Certificate Revocation List



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             (CRL) Profile", RFC 3279, April 2002.

   [RFC4020] Kompella, K. and A. Zinin, "Early IANA Allocation of
             Standards Track Code Points", BCP 100, RFC 4020, February
             2005.

   [RFC4211] Schaad, J., "Internet X.509 Public Key Infrastructure
             Certificate Request Message Format (CRMF)", RFC 4211,
             September 2005.

   [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
             IANA Considerations Section in RFCs", BCP 26, RFC 5226, May
             2008.

   [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.

   [RFC5480] Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk,
             "Elliptic Curve Cryptography Subject Public Key
             Information", RFC 5480, March 2009.

   [RFC6090] McGrew, D., Igoe, K., and M. Salter, "Fundamental Elliptic
             Curve Cryptography Algorithms", RFC 6090, February 2011.

   [RFC6485] Huston, G., "The Profile for Algorithms and Key Sizes for
             Use in the Resource Public Key Infrastructure (RPKI)",
             RFC 6485, February 2012.

   [RFC6487] Huston, G., Michaelson, G., and R. Loomans, "A Profile for
             X.509 PKIX Resource Certificates", RFC 6487, February 2012.

   [SHS]  National Institute of Standards and Technology (NIST), "FIPS
             Publication 180-3: Secure Hash Standard", FIPS Publication
             180-3, October 2008.

   [ID.sidr-bgpsec-protocol]  Lepinski, M., "BGPSEC Protocol
             Specification", draft-ietf-sidr-bgpsec-protocol, work-in-
             progress.

   [ID.bgpsec-pki-profiles]  Reynolds, M. and S. Turner, "A Profile for
             BGPSEC Router Certificates, Certificate Revocation Lists,
             and Certification Requests", draft-ietf-sidr-bpgsec-pki-
             profiles, work-in-progress.






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11.1.  Informative References

             None.

Authors' Addresses

   Sean Turner
   IECA, Inc.
   3057 Nutley Street, Suite 106
   Fairfax, VA 22031
   USA

   EMail: turners@ieca.com






































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