Secure Inter-Domain Routing Working Group                    M. Reynolds
Internet-Draft                                                      IPSw
Updates: 6487 (if approved)                                    S. Turner
Intended Status: Standards Track                                    IECA
Expires: April 16, October 19, 2013                                        S. Kent
                                                        October 13, 2012
                                                          April 17, 2013

               A Profile for BGPSEC Router Certificates,
        Certificate Revocation Lists, and Certification Requests


   This document defines a standard profile for X.509 certificates for
   the purposes of supporting validation of Autonomous System (AS) paths
   in the Border Gateway Protocol (BGP), as part of an extension to that
   protocol known as BGPSEC.  BGP is a critical component for the proper
   operation of the Internet as a whole.  The BGPSEC protocol is under
   development as a component to address the requirement to provide
   security for the BGP protocol.  The goal of BGPSEC is to design a
   protocol for full AS path validation based on the use of strong
   cryptographic primitives.  The end-entity (EE) certificates specified
   by this profile are issued under Resource Public Key Infrastructure
   (RPKI) Certification Authority (CA) certificates, containing the AS
   Identifier Delegation extension, to routers within the Autonomous
   System (AS).  The certificate asserts that the router(s) holding the
   private key are authorized to send out secure route advertisements on
   behalf of the specified AS.  This document also profiles the
   Certificate Revocation List (CRL), profiles the format of
   certification requests, and specifies Relying Party certificate path
   validation procedures.  The document extends the RPKI; therefore,
   this documents updates the RPKI Resource Certificates Profile (RFC

Status of this Memo

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1.  Introduction

   This document defines a profile for X.509 end-entity (EE)
   certificates [RFC5280] for use in the context of certification of
   Autonomous System (AS) paths in the Border Gateway Protocol Security
   (BGPSEC) protocol.  Such certificates are termed "BGPSEC Router
   Certificates".  The holder of the private key associated with a
   BGPSEC Router Certificate is authorized to send secure route
   advertisements (BGPSEC UPDATEs) on behalf of the AS named in the
   certificate.  That is, a router holding the private key may send to
   its BGP peers, route advertisements that contain the specified AS
   number as the last item in the AS PATH attribute.  A key property
   that BGPSEC will provide is that every AS along the AS PATH can
   verify that the other ASes along the path have authorized the
   advertisement of the given route (to the next AS along the AS PATH).

   This document is a profile of [RFC6487], which is a profile of
   [RFC5280], and it updates [RFC6487].  It establishes requirements
   imposed on a Resource Certificate that is used as a BGPSEC Router
   Certificate, i.e., it defines constraints for certificate fields and
   extensions for the certificate to be valid in this context.  This
   document also profiles the Certificate Revocation List (CRL) and
   certification requests.  Finally, this document specifies the Relying
   Party (RP) certificate path validation procedures.

1.1.  Terminology

   It is assumed that the reader is familiar with the terms and concepts
   described in "A Profile for X.509 PKIX Resource Certificates"
   [RFC6487], "BGPSEC Protocol Specification" [ID.sidr-bgpsec-protocol],
   "A Border Gateway Protocol 4 (BGP-4)" [RFC4271], "BGP Security
   Vulnerabilities Analysis" [RFC4272], "Considerations in Validating
   the Path in BGP" [RFC5123], and "Capability Advertisement with BGP-4"

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "OPTIONAL" in this document are to be interpreted as described in

2.  Describing Resources in Certificates

   Figure 1 depicts some of the entities in the RPKI and some of the
   products generated by RPKI entities.  IANA issues a Certification
   Authority (CA) to a Regional Internet Registries (RIR).  The RIR, in
   turn, issues a CA certificate to an Internet Service Providers (ISP).
    The ISP in turn issues End-Entity (EE) Certificates to itself as
   well as CRLs.  These certificates are referred to as "Resource
   Certificates", and are profiled in [RFC6487].  The [RFC6480]
   envisioned using Resource Certificates to generate Manifests
   [RFC6486] and Route Origin Authorizations (ROAs) [RFC6482].  ROAs and
   Manifests also include the Resource Certificates used to sign them.

                +---------+   +------+
                | CA Cert |---| IANA |
                +---------+   +------+
                      +---------+   +-----+
                      | CA Cert |---| RIR |
                      +---------+   +-----+
                             +---------+   +-----+
                             | CA Cert |---| ISP |
                             +---------+   +-----+
                              / |            | |
                   +-----+   /  |            | |   +-----+
                   | CRL |--+   |            | +---| ROA |
                   +-----+      |            |     +-----+
                                |            |   +----------+
                       +----+   |            +---| Manifest |
                     +-| EE |---+                +----------+
                     | +----+
                                Figure 1

   This document defines another type of Resource Certificate, which is
   referred to as a "BGPSEC Router Certificate".  The purpose of this
   certificate is explained in Section 1 and falls within the scope of
   appropriate uses defined within [RFC6484].  The issuance of BGPSEC
   Router Certificates has minimal impact on RPKI CAs because the RPKI
   CA certificate and CRL profile remain unchanged (i.e., they are as
   specified in [RFC6487]).  Further, the algorithms used to generate
   RPKI CA certificates that issue the BGPSEC Router Certificates and
   the CRLs necessary to check the validity of the BGPSEC Router
   Certificates remain unchanged (i.e., they are as specified in
   [RFC6485]).  The only impact is that the RPKI CAs will need to be
   able to process a profiled certificate request (see Section 5) signed
   with algorithms found in [ID.sidr-bgpsec-algs].  The use of BGPSEC
   Router Certificates in no way affects RPKI RPs that process Manifests
   and ROAs because the public key found in the BGPSEC Router
   Certificate is only ever used to verify the signature on the BGPSEC
   certificate request (only CAs process these) and the signature on a
   BGPSEC Update Message [ID.sidr-bgpsec-protocol] (only BGPSEC routers
   process these).

   Only the differences between this profile and the profile in
   [RFC6487] are listed.  Note that BGPSEC Router Certificates are EE
   certificates and as such there is no impact on process described in

3.  Updates to [RFC6487]

3.1  BGPSEC Router Certificate Fields

   A BGPSEC Router Certificate is a valid X.509 public key certificate,
   consistent with the PKIX profile [RFC5280], containing the fields
   listed in this section.  This profile is also based on [RFC6487] and
   only the differences between this profile and the profile in
   [RFC6487] are listed.  Subject

   This field identifies the router to which the certificate has been
   issued.  Consistent with [RFC6487], only two attributes are allowed
   in the Subject field: common name and serial number.  Moreover, the
   only common name encoding options that are supported are
   printableString and UTF8String.  For BGPSEC Router Certificates, it
   is RECOMMENDED that the common name attribute contain the literal
   string "ROUTER-" followed by the 32-bit AS Number [RFC3779] encoded
   as eight hexadecimal digits and that the serial number attribute
   contain the 32-bit BGP Identifier [RFC4271] (i.e., the router ID)
   encoded as eight hexadecimal digits.  If the same certificate is
   issued to more than one router (hence the private key is shared among
   these routers), the choice of the router ID used in this name is at
   the discretion of the Issuer.  Note that router IDs are not
   guaranteed to be unique across the Internet, and thus the Subject
   name in a BGPSEC Router Certificate issued using this convention also
   is not guaranteed to be unique across different issuers.  However,
   each certificate issued by an individual CA MUST contain a Subject
   name that is unique within that context.

3.1.2.  Subject Public Key Info

   Refer to section 3.1 of [ID.sidr-bgpsec-algs].

3.1.3.  BGPSEC Router Certificate Version 3 Extension Fields

   The following X.509 V3 extensions MUST be present (or MUST be absent,
   if so stated) in a conforming BGPSEC Router Certificate, except where
   explicitly noted otherwise.  No other extensions are allowed in a
   conforming BGPSEC Router Certificate.  Basic Constraints

   BGPSEC speakers are EEs; therefore, the Basic Constraints extension
   must not be present, as per [RFC6487].  Extended Key Usage

   BGPSEC Router Certificates MUST include the Extended Key Usage (EKU)
   extension.  As specified, in [RFC6487] this extension MUST be marked
   as non-critical.  This document defines one EKU for BGPSEC Router

     id-kp OBJECT IDENTIFIER ::=
        { iso(1) identified-organization(3) dod(6) internet(1)
          security(5) mechanisms(5) pkix(7) kp(3) }

     id-kp-bgpsec-router OBJECT IDENTIFIER ::= { id-kp TBD }

   Relying Parties MUST require the extended key usage extension to be
   present in a BGPSEC Router Certificate.  If multiple KeyPurposeId
   values are included, the relying parties need not recognize all of
   them, as long as the required KeyPurposeId value is present.  BGPSEC
   RPs MUST reject certificates that do not contain the BGPSEC Router
   EKU even if they include the anyExtendedKeyUsage OID defined in
   [RFC5280].  Subject Information Access

   This extension is not used in BGPSEC Router Certificates. It MUST be
   omitted.  IP Resources

   This extension is not used in BGPSEC Router Certificates. It MUSt be
   omitted.  AS Resources

   Each BGPSEC Router Certificate MUST include the AS Resource
   Identifier Delegation extension, as specified in section 4.8.11 of
   [RFC6487].  The AS Resource Identifier Delegation extension MUST
   include exactly one AS number, and the "inherit" element MUST NOT be

3.2.  BGPSEC Router Certificate Request Profile

   Refer to section 6 of [RFC6487].  The only differences between this
   profile and the profile in [RFC6487] are:

    o The ExtendedKeyUsage extension request MUST be included and the CA
      MUST honor the request;

    o The SubjectPublicKeyInfo and PublicKey fields are specified in
      [ID.sidr-bgpsec-algs]; and,

    o The request is signed with the algorithms specified in [ID.sidr-

3.3.  BGPSEC Router Certificate Validation

   The validation procedure used for BGPSEC Router Certificates is
   identical to the validation procedure described in Section 7 of
   [RFC6487].  The exception is that the constraints applied come from
   this specification (e.g., in step 3: the certificate contains all the
   field that must be present - refers to the fields that are required
   by this specification).

   The differences are as follows:

    o BGPSEC Router Certificates MUST include the BGPSEC EKU defined in

    o BGPSEC Router Certificates MUST NOT include the SIA extension.

    o BGPSEC Router Certificates MUST NOT include the IP Resource

    o BGPSEC Router Certificates MUST include the AS Resource Identifier
      Delegation extension.

    o BGPSEC Router Certificate MUST include the "Subject Public Key
      Info" described in [ID.sidr-bgpsec-algs] as it updates [RFC6485].

      NOTE: The cryptographic algorithms used by BGPSEC routers are
      found in [ID.sidr-bgpsec-algs].  Currently, the algorithms
      specified in [ID.sidr-bgpsec-algs] and [RFC6485] are different.
      BGPSEC RPs will need to support algorithms that are needed to
      validate BGPSEC signatures as well as the algorithms that are
      needed to validate signatures on BGPSEC certificates, RPKI CA
      certificates, and RPKI CRLs.

4.  Design Notes

   The BGPSEC Router Certificate profile is based on the Resource
   Certificate profile as specified in [RFC6485].  As a result, many of
   the design choices herein are a reflection of the design choices that
   were taken in that prior work.  The reader is referred to [RFC6484]
   for a fuller discussion of those choices.

5.  Security Considerations

   The Security Considerations of [RFC6487] apply.

   A bgpsec certificate will fail RPKI validation, as defined in
   [RFC6487], because the algorithm suite is different. Consequently, a
   RP needs to identify the EKU before applying the correspondent

   A BGPSEC Router Certificate is an extension of the RPKI [RFC6480] to
   encompass routers.  It is a building block of the larger BGPSEC
   security protocol used to validate signatures on BGPSEC Signature-
   Segment origination of Signed-Path segments [ID.sidr-bgpsec-
   protocol].  Thus its essential security function is the secure
   binding of an AS number to a public key, consistent with the RPKI
   allocation/assignment hierarchy.

6.  IANA Considerations


7.  Acknowledgements

   We would like to thanks Geoff Huston, George Michaelson, and Robert
   Loomans for their work on [RFC6487], which this work is based on.  In
   addition, the efforts of Steve Kent and Matt Lepinski were
   instrumental in preparing this work.  Additionally, we'd like to
   thank Roque Gagliano, Sandra Murphy, and Geoff Huston for their
   reviews and comments.

8.  References

8.1.  Normative References

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

   [RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
             Addresses and AS Identifiers", RFC 3779, June 2004.

   [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border
             Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006.

   [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.

   [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.

   [ID.sidr-bgpsec-algs]  Reynolds, M. and S. Turner, "BGP Algorithms,
             Key Formats, & Signature Formats", draft-ietf-sidr-bgpsec-
             algs, work-in-progress.

8.2.  Informative References

   [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
             RFC 4272, January 2006.

   [RFC5123] White, R. and B. Akyol, "Considerations in Validating the
             Path in BGP", RFC 5123, February 2008.

   [RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
             with BGP-4", RFC 5492, February 2009.

   [RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
             Secure Internet Routing", RFC 6480, February 2012.

   [RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
             Origin Authorizations (ROAs)", RFC 6482, February 2012.

   [RFC6484] Kent, S., Kong, D., Seo, K., and R. Watro, "Certificate
             Policy (CP) for the Resource Public Key Infrastructure
             (RPKI)", BCP 173, RFC 6484, February 2012.

   [RFC6486] Austein, R., Huston, G., Kent, S., and M. Lepinski,
             "Manifests for the Resource Public Key Infrastructure
             (RPKI)", RFC 6486, February 2012.

   [ID.sidr-algorithm-agility]  Gagliano, R., Kent, S., and S. Turner,
             "Algorithm Agility Procedure for RPKI", draft-ietf-sidr-
             algorithm-agility, work-in-progress.

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

Appendix A.  ASN.1 Module

   BGPSECEKU { iso(1) identified-organization(3) dod(6) internet(1)
     security(5) mechanisms(5) pkix(7) id-mod(0) TBD }



     -- EXPORTS ALL --


     -- OID Arc --

     id-kp  OBJECT IDENTIFIER  ::= {
       iso(1) identified-organization(3) dod(6) internet(1)
       security(5) mechanisms(5) kp(3) }

     -- BGPSEC Router Extended Key Usage --

     id-kp-bgpsec-router OBJECT IDENTIFIER ::= { id-kp TBD }


Appendix B.  Example BGPSEC Router Certificate

Appendix C.  Example BGPSEC Router Certificate Request
Appendix D.  Change Log

   Please delete this section prior to publication.

D.1.  Changes from sidr-bgpsec-pki-profiles-03 to sidr-bgpsec-pki-

   In s2.1, removed the phrase "another BGPSEC Router Certificate (only
   BGPSEC routers process these)" because the BGPSEC certificates are
   only ever EE certificates and they're never used to verify another
   certificate only the PDUs that are signed.

   Added new s3.1.3.1 to explicitly state that EE certificates are only
   ever EE certs.

D.2.  Changes from sidr-bgpsec-pki-profiles-02 to sidr-bgpsec-pki-

   Updated s3.3 to clarifify restrictions on path validation procedures
   are in this specification (1st para was reworded).

   Updated s3.3 to point to s3.1.3.1 for BGPSEC EKU (thanks Tom).

D.3.  Changes from sidr-bgpsec-pki-profiles-01 to sidr-bgpsec-pki-

   Updated references.

D.4.  Changes from sidr-bgpsec-pki-profiles-00 to sidr-bgpsec-pki-

   Added an ASN.1 Module and corrected the id-kp OID in s3.1.3.1.

D.5.  Changes from turner-bgpsec-pki-profiles-02 to sidr-bgpsec-pki-

   Added this change log.

   Amplified that a BGPSEC RP will need to support both the algorithms
   in [ID.sidr-bgpsec-algs] for BGPSEC and the algorithms in [ID.sidr-
   rpki-algs] for certificates and CRLs.

   Changed the name of AS Resource extension to AS Resource Identifier
   Delegation to match what's in RFC 3779.

D.6.  Changes from turner-bgpsec-pki-profiles -01 to -02

   Added text in Section 2 to indicate that there's no impact on the
   procedures defined in [ID.sidr-algorithm-agility].

   Added a security consideration to let implementers know the BGPSEC
   certificates will not pass RPKI validation [RFC6487] and that keying
   off the EKU will help tremendously.

D.7.  Changes from turner-bgpsec-pki-profiles -00 to -01

   Corrected Section 2 to indicate that CA certificates are also RPKI

   Removed sections and text that was already in [RFC6487]. This will
   make it easier for reviewers to figure out what is different.

   Modified Section 6 to use 2119-language.

   Removed requirement from Section 6 to check that the AS # in the
   certificate is the last number in the AS path information of each BGP
   UPDATE message.  Moved to [ID.sidr-bgpsec-protocol].

Authors' Addresses

   Mark Reynolds
   Island Peak Software
   328 Virginia Road
   Concord, MA 01742


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


   Steve Kent
   Raytheon BBN Technologies
   10 Moulton St.
   Cambridge, MA 02138