A Profile for BGPSEC Router Certificates, Certificate Revocation Lists, and Certification Requests
draft-ietf-sidr-bgpsec-pki-profiles-08

SIDR Working Group                                           M. Reynolds
Internet-Draft                                                      IPSw
Updates: 6487 (if approved)                                    S. Turner
Intended status: Standards Track                              IECA, Inc.
Expires: February 14, 2015                                       S. Kent
                                                                     BBN
                                                         August 13, 2014

A Profile for BGPSEC Router Certificates, Certificate Revocation Lists,
                       and Certification Requests
                 draft-ietf-sidr-bgpsec-pki-profiles-08

Abstract

   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
   6487).

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any

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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on February 14, 2015.

Copyright Notice

   Copyright (c) 2014 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
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   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.

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.

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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"
   [I-D.ietf-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" [RFC5492].

   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].

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 Provider (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.

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

                   Figure 1: RPKI and BGPsec Hierarchies

   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
   [I-D.ietf-sidr-rfc6485bis]).  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
   [I-D.ietf-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
   [I-D.ietf-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
   [RFC6916].

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3.  Updates to RFC 6487

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.

3.1.1.  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 more than one certificate
   for an AS is issued (i.e., more than one router gets a certificate
   for the AS and hence the private key is shared among more than one
   router), the choice of the router ID used in Subject 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 [I-D.ietf-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.

3.1.3.1.  Basic Constraints

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

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3.1.3.2.  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
   Certificates:

     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 30 }

   Relying Parties MUST require the extended key usage extension 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].

3.1.3.3.  Subject Information Access

   This extension is not used in BGPSEC Router Certificates.  It MUST be
   absent.

3.1.3.4.  IP Resources

   This extension is not used in BGPSEC Router Certificates.  It MUST be
   absent.

3.1.3.5.  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 only one AS number, and the "inherit" element MUST NOT be
   specified.

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;

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

   o  The attributes field contains the ASN extension with exactly one
      ASN.

   o  The request is signed with the algorithms specified in
      [I-D.ietf-sidr-bgpsec-algs].

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).

   {spt: should the algorithm fail if there's more than one in the
   cert?}

   The differences are as follows:

   o  BGPSEC Router Certificates MUST include the BGPSEC EKU defined in
      Section 3.1.3.1.

   o  BGPSEC Router Certificates MUST NOT include the SIA extension.

   o  BGPSEC Router Certificates MUST NOT include the IP Resource
      extension.

   o  BGPSEC Router Certificates MUST include the AS Resource Identifier
      Delegation extension and only one AS number.

   o  BGPSEC Router Certificate MUST include the "Subject Public Key
      Info" described in [I-D.ietf-sidr-bgpsec-algs] as it updates
      [I-D.ietf-sidr-rfc6485bis].

   NOTE: The cryptographic algorithms used by BGPSEC routers are found
   in [I-D.ietf-sidr-bgpsec-algs].  Currently, the algorithms specified
   in [I-D.ietf-sidr-bgpsec-algs] and [I-D.ietf-sidr-rfc6485bis] 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.

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4.  Design Notes

   The BGPSEC Router Certificate profile is based on the Resource
   Certificate profile as specified in [I-D.ietf-sidr-rfc6485bis].  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.

   One design choice made by this document is to include one AS number
   per certificate.  Simplicty is the driving rationale.  If a router
   supports more than one AS, the router can simply be issued another
   certificate though the impact on the router is that additional secure
   storage may be needed for additional private keys.

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
   validation.

   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
   [I-D.ietf-sidr-bgpsec-protocol].  Thus its essential security
   function is the secure binding of one or more AS numbers to a public
   key, consistent with the RPKI allocation/assignment hierarchy.

6.  IANA Considerations

   None.

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, Geoff Huston, Randy Bush, and
   Rob Austein for their reviews and comments.  Finally, we'd like to
   thank Russ Housley for assigning us an OID for the ASN.1 module.

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8.  References

8.1.  Normative References

   [I-D.ietf-sidr-bgpsec-algs]
              Turner, S., "BGP Algorithms, Key Formats, & Signature
              Formats", draft-ietf-sidr-bgpsec-algs-08 (work in
              progress), July 2014.

   [I-D.ietf-sidr-rfc6485bis]
              Huston, G. and G. Michaelson, "The Profile for Algorithms
              and Key Sizes for use in the Resource Public Key
              Infrastructure", draft-ietf-sidr-rfc6485bis-01 (work in
              progress), March 2014.

   [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., Li, T., and S. Hares, "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.

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

8.2.  Informative References

   [I-D.ietf-sidr-bgpsec-protocol]
              Lepinski, M., "BGPSEC Protocol Specification", draft-ietf-
              sidr-bgpsec-protocol-09 (work in progress), July 2014.

   [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.

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   [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.

   [RFC6916]  Gagliano, R., Kent, S., and S. Turner, "Algorithm Agility
              Procedure for the Resource Public Key Infrastructure
              (RPKI)", BCP 182, RFC 6916, April 2013.

Appendix A.  ASN.1 Module

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

     security(5) mechanisms(5) pkix(7) id-mod(0)

     id-mod-bgpsec-eku(84) }

     DEFINITIONS EXPLICIT TAGS ::=

     BEGIN

     -- EXPORTS ALL --

     -- IMPORTS NOTHING --

     -- 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 30 }

     END

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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-07 to sidr-bgpsec-pki-
      profiles-08

   Changed references to RFC 6485 to [I-D.ietf-sidr-rfc6485bis] and
   added OIDs for ASN.1 module.  Certificate and certification request
   restricted to contain one ASN.

D.2.  Changes from sidr-bgpsec-pki-profiles-06 to sidr-bgpsec-pki-
      profiles-07

   Added text to multiple AS numbers in a single certificate.  Updated
   reference to RFC 6916.

D.3.  Changes from sidr-bgpsec-pki-profiles-05 to sidr-bgpsec-pki-
      profiles-06

   Keep alive version.

D.4.  Changes from sidr-bgpsec-pki-profiles-04 to sidr-bgpsec-pki-
      profiles-05

   Keep alive version.

D.5.  Changes from sidr-bgpsec-pki-profiles-03 to sidr-bgpsec-pki-
      profiles-04

   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.6.  Changes from sidr-bgpsec-pki-profiles-02 to sidr-bgpsec-pki-
      profiles-03

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

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

D.7.  Changes from sidr-bgpsec-pki-profiles-01 to sidr-bgpsec-pki-
      profiles-02

   Updated references.

D.8.  Changes from sidr-bgpsec-pki-profiles-00 to sidr-bgpsec-pki-
      profiles-01

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

D.9.  Changes from turner-bgpsec-pki-profiles-02 to sidr-bgpsec-pki-
      profiles-00

   Added this change log.

   Amplified that a BGPSEC RP will need to support both the algorithms
   in [I-D.ietf-sidr-bgpsec-algs] for BGPSEC and the algorithms in
   [RFC6487] for certificates and CRLs.

   Changed the name of AS Resource extension to AS Resource Identifier
   Delegation to match what's in [RFC3779].

D.10.  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 [RFC6916].

   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.11.  Changes from turner-bgpsec-pki-profiles -00 to -01

   Corrected Section 2 to indicate that CA certificates are also RPKI
   certificates.

   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 [I-D.ietf-sidr-bgpsec-protocol].

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Authors' Addresses

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

   Email: mcr@islandpeaksoftware.com

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

   Phone: +1-703-628-3180
   Email: turners@ieca.com

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

   Email: kent@bbn.com

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