Internet DRAFT - draft-ietf-sidr-bgpsec-pki-profiles
draft-ietf-sidr-bgpsec-pki-profiles
Secure Inter-Domain Routing Working Group M. Reynolds
Internet-Draft IPSw
Updates: 6487 (if approved) S. Turner
Intended status: Standard Track sn3rd
Expires: July 9, 2017 S. Kent
BBN
January 5, 2017
A Profile for BGPsec Router Certificates,
Certificate Revocation Lists, and Certification Requests
draft-ietf-sidr-bgpsec-pki-profiles-21
Abstract
This document defines a standard profile for X.509 certificates used
to enable 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 the standard for inter-domain routing in the
Internet; it is the "glue" that holds the Internet together. BGPsec
is being developed as one component of a solution that addresses the
requirement to provide security for BGP. The goal of BGPsec is to
provide full AS path validation based on the use of strong
cryptographic primitives. The end-entity (EE) certificates specified
by this profile are issued to routers within an Autonomous System.
Each of these certificates is issued under a Resource Public Key
Infrastructure (RPKI) Certification Authority (CA) certificate.
These CA certificates and EE certificates both contain the AS
Identifier Delegation extension. An EE certificate of this type
asserts that the router(s) holding the corresponding private key are
authorized to emit secure route advertisements on behalf of the
AS(es) specified in the certificate. This document also profiles the
format of certification requests, and specifies Relying Party (RP)
certificate path validation procedures for these EE certificates.
This 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
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and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
Copyright Notice
Copyright (c) 2017 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Describing Resources in Certificates . . . . . . . . . . . . . 3
3. Updates to [RFC6487] . . . . . . . . . . . . . . . . . . . . . 5
3.1 BGPsec Router Certificate Fields . . . . . . . . . . . . . 5
3.1.1. Subject . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.2. Subject Public Key Info . . . . . . . . . . . . . . . 5
3.1.3. BGPsec Router Certificate Version 3 Extension Fields . 5
3.1.3.1. Basic Constraints . . . . . . . . . . . . . . . . 5
3.1.3.2. Extended Key Usage . . . . . . . . . . . . . . . . 5
3.1.3.3. Subject Information Access . . . . . . . . . . . . 6
3.1.3.4. IP Resources . . . . . . . . . . . . . . . . . . . 6
3.1.3.5. AS Resources . . . . . . . . . . . . . . . . . . . 6
3.2. BGPsec Router Certificate Request Profile . . . . . . . . 6
3.3. BGPsec Router Certificate Validation . . . . . . . . . . . 7
3.4. Router Certificates and Signing Functions in the RPKI . . 7
4. Design Notes . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Implementation Considerations . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . . 11
Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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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 BGPsec. 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(es)
named in the certificate. A router holding the private key is
authorized to send route advertisements (to its peers) identifying
the router's ASN as the source of the advertisements. A key property
provided by BGPsec 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]; thus this document 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 certification requests
used to acquire BGPsec Router Certificates. Finally, this document
specifies the Relying Party (RP) certificate path validation
procedures for these certificates.
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"
[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) certificate to each Regional Internet Registry (RIR).
The RIR, in turn, issues a CA certificate to an Internet Service
Provider (ISP). The ISP in turn issues EE Certificates to itself to
enable verification of signatures on RPKI signed objects. The CA
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also generates Certificate Revocation Lists (CRLs). These CA and EE
certificates are referred to as "Resource Certificates", and are
profiled in [RFC6487]. [RFC6480] envisioned using Resource
Certificates to enable verification of Manifests [RFC6486] and Route
Origin Authorizations (ROAs) [RFC6482]. ROAs and Manifests include
the Resource Certificates used to verify 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
[RFC7935]). The only impact is that 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]. BGPsec Router
Certificates are used only 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); BGPsec Router Certificates are not used to process
Manifests and ROAs or verify signatures on Certificates or CRLs.
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This document enumerates only the differences between this profile
and the profile in [RFC6487]. Note that BGPsec Router Certificates
are EE certificates and as such there is no impact on process
described in [RFC6916].
3. Updates to [RFC6487]
3.1 BGPsec Router Certificate Fields
A BGPsec Router Certificate is consistent with the profile in
[RFC6487] as modified by the specifications in this section. As
such, it is a valid X.509 public key certificate and consistent with
the PKIX profile [RFC5280]. The differences between this profile and
the profile in [RFC6487] are specified in this section.
3.1.1. Subject
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 there is more than one AS number, the
choice of which to include in the common name is at the discretion of
the Issuer. 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.
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
3.1.3.1. Basic Constraints
BGPsec speakers are EEs; therefore, the Basic Constraints extension
must not be present, as per [RFC6487].
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:
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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 }
A BGPsec router MUST require the extended key usage extension to be
present in a BGPsec Router Certificate it receives. If multiple
KeyPurposeId values are included, the BGPsec routers need not
recognize all of them, as long as the required KeyPurposeId value is
present. BGPsec routers 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
omitted.
3.1.3.4. IP Resources
This extension is not used in BGPsec Router Certificates. It MUST be
omitted.
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 one or more AS numbers, 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 Basic Constraints extension:
If included, the CA MUST NOT honor the cA boolean if set to TRUE.
o The Extended Key Usage extension:
If included, id-kp-bgpsec-router MUST be present (see Section
3.1). If included, the CA MUST honor the request for id-kp-
bgpsec-router.
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o The Subject Information Access extension:
If included, the CA MUST NOT honor the request to include the
extension.
o The SubjectPublicKeyInfo field is specified in [ID.sidr-bgpsec-
algs].
o The request is signed with the algorithms specified in [ID.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] (and any RFC that updates that procedure), as modified
below. For example, in step 3: "The certificate contains all fields
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 Router EKU
defined in Section 3.1.3.2.
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.
o BGPsec Router Certificate MUST include the subjectPublicKeyInfo
described in [ID.sidr-bgpsec-algs].
NOTE: BGPsec RPs will need to support the algorithms in [ID.sidr-
bgpsec-algs], which are used to validate BGPsec signatures, as well
as the algorithms in [RFC7935], which are needed to validate
signatures on BGPsec certificates, RPKI CA certificates, and RPKI
CRLs.
3.4. Router Certificates and Signing Functions in the RPKI
As described in Section 1, the primary function of BGPsec route
certificates in the RPKI is for use in the context of certification
of Autonomous System (AS) paths in the BGPsec protocol.
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The private key associated with a router EE certificate may be used
multiple times in generating signatures in multiple instances of the
BGPsec_Path Attribute Signature Segments [ID.sidr-bgpsec-protocol].
I.e., the BGPsec router certificate is used to validate multiple
signatures.
BGPsec router certificates are stored in the issuing CA's repository,
where a repository following RFC6481 MUST use a .cer filename
extension for the certificate file.
4. Design Notes
The BGPsec Router Certificate profile is based on the Resource
Certificate profile as specified in [RFC7935]. 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.
CAs are required by the Certificate Policy (CP) [RFC6484] to issue
properly formed BGPsec Router Certificates regardless of what is
present in the certification request so there is some flexibility
permitted in the certificate requests:
o BGPsec Router Certificates are always EE certificates; therefore,
requests to issue a CA certificate result in EE certificates;
o BGPsec Router Certificates are always EE certificates; therefore,
requests for Key Usage extension values keyCertSign and cRLSign
result in certificates with neither of these values;
o BGPsec Router Certificates always include the BGPsec Rouer EKU
value; therefore, request without the value result in certificates
with the value; and,
o BGPsec Router Certificates never include the Subject Information
Access extension; therefore, request with this extension result in
certificates without the extension.
Note that this behavior is similar to the CA including the AS
Resource Identifier Delegation extension in issued BGPsec Router
Certificates despite the fact it is not present in the request.
5. Implementation Considerations
This document permits the operator to include a list of ASNs in a
BGPsec Router Certificate. In that case, the router certificate would
become invalid if any one of the ASNs is removed from any superior CA
certificate along the path to a trust anchor. Operators could choose
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to avoid this possibility by issuing a separate BGPsec Router
Certificate for each distinct ASN, so that the router certificates
for ASNs that are retained in the superior CA certificate would
remain valid.
6. Security Considerations
The Security Considerations of [RFC6487] apply.
A BGPsec Router Certificate will fail RPKI validation, as defined in
[RFC6487], because the cryptographic algorithms used are different.
Consequently, a RP needs to identify the EKU to determine the
appropriate Validation constraint.
A BGPsec Router Certificate is an extension of the RPKI [RFC6480] to
encompass routers. It is a building block BGPsec and is 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 one or more AS numbers to
a public key, consistent with the RPKI allocation/assignment
hierarchy.
Hash functions [ID.sidr-bgpsec-algs] are used when generating the two
key identifier extensions (i.e., Subject Key Identifier and Issuer
Key Identifier) included in BGPsec certificates. However as noted in
[RFC6818], collision resistance is not a required property of one-way
hash functions when used to generate key identifiers. Regardless,
hash collisions are unlikely, but they are possible and if detected
an operator should be alerted. A subject key identifier collision
might cause the incorrect certificate to be selected from the cache,
resulting in a failed signature validation.
7. IANA Considerations
This document makes use of two object identifiers in the SMI Registry
for PKIX. One is for the ASN.1 module in Appendix A and it comes
from the SMI Security for PKIX Module Identifier IANA registry (id-
mod-bgpsec-eku). The other is for the BGPsec router EKU defined in
Section 3.1.3.2 and Appendix A and it comes from the SMI Security for
PKIX Extended Key Purpose IANA registry. These OIDs were assigned
before management of the PKIX Arc was handed to IANA. No IANA
allocations are request of IANA, but please update the references in
those registries when this document is published by the RFC editor.
8. Acknowledgements
We would like to thank Geoff Huston, George Michaelson, and Robert
Loomans for their work on [RFC6487], which this work is based on. In
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addition, the efforts of Matt Lepinski were instrumental in preparing
this work. Additionally, we'd like to thank Rob Austein, Roque
Gagliano, Richard Hansen, Geoff Huston, David Mandelberg, Sandra
Murphy, and Sam Weiller for their reviews and comments.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI
10.17487/RFC2119, March 1997, <http://www.rfc-
editor.org/info/rfc2119>.
[RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
Addresses and AS Identifiers", RFC 3779, DOI
10.17487/RFC3779, June 2004, <http://www.rfc-
editor.org/info/rfc3779>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border
Gateway Protocol 4 (BGP-4)", RFC 4271, DOI
10.17487/RFC4271, January 2006, <http://www.rfc-
editor.org/info/rfc4271>.
[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, DOI 10.17487/RFC5280, May 2008,
<http://www.rfc-editor.org/info/rfc5280>.
[RFC6486] Austein, R., Huston, G., Kent, S., and M. Lepinski,
"Manifests for the Resource Public Key Infrastructure
(RPKI)", RFC 6486, DOI 10.17487/RFC6486, February 2012,
<http://www.rfc-editor.org/info/rfc6486>.
[RFC6487] Huston, G., Michaelson, G., and R. Loomans, "A Profile for
X.509 PKIX Resource Certificates", RFC 6487, DOI
10.17487/RFC6487, February 2012, <http://www.rfc-
editor.org/info/rfc6487>.
[RFC7935] Huston, G. and G. Michaelson, Ed., "The Profile for
Algorithms and Key Sizes for Use in the Resource Public Key
Infrastructure", RFC 7935, DOI 10.17487/RFC7935, August
2016, <http://www.rfc-editor.org/info/rfc7935>.
[ID.sidr-bgpsec-protocol] Lepinski, M. and K. Sriram, "BGPsec
Protocol Specification", draft-ietf-sidr-bgpsec-protocol,
work-in-progress.
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[ID.sidr-bgpsec-algs] Turner, S., "BGP Algorithms, Key Formats, &
Signature Formats", draft-ietf-sidr-bgpsec-algs, work-in-
progress.
9.2. Informative References
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006,
<http://www.rfc-editor.org/info/rfc4272>.
[RFC5123] White, R. and B. Akyol, "Considerations in Validating the
Path in BGP", RFC 5123, DOI 10.17487/RFC5123, February
2008, <http://www.rfc-editor.org/info/rfc5123>.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February 2009,
<http://www.rfc-editor.org/info/rfc5492>.
[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
February 2012, <http://www.rfc-editor.org/info/rfc6480>.
[RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
Origin Authorizations (ROAs)", RFC 6482, DOI
10.17487/RFC6482, February 2012, <http://www.rfc-
editor.org/info/rfc6482>.
[RFC6484] Kent, S., Kong, D., Seo, K., and R. Watro, "Certificate
Policy (CP) for the Resource Public Key Infrastructure
(RPKI)", BCP 173, RFC 6484, DOI 10.17487/RFC6484, February
2012, <http://www.rfc-editor.org/info/rfc6484>.
[RFC6486] Austein, R., Huston, G., Kent, S., and M. Lepinski,
"Manifests for the Resource Public Key Infrastructure
(RPKI)", RFC 6486, DOI 10.17487/RFC6486, February 2012,
<http://www.rfc-editor.org/info/rfc6486>.
[RFC6916] Gagliano, R., Kent, S., and S. Turner, "Algorithm Agility
Procedure for the Resource Public Key Infrastructure
(RPKI)", BCP 182, RFC 6916, DOI 10.17487/RFC6916, April
2013, <http://www.rfc-editor.org/info/rfc6916>.
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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) pkix(7) kp(3) }
-- BGPsec Router Extended Key Usage --
id-kp-bgpsec-router OBJECT IDENTIFIER ::= { id-kp 30 }
END
Authors' Addresses
Mark Reynolds
Island Peak Software
328 Virginia Road
Concord, MA 01742
Email: mcr@islandpeaksoftware.com
Sean Turner
sn3rd
EMail: sean@sn3rd.com
Stephen Kent
Raytheon BBN Technologies
10 Moulton St.
Cambridge, MA 02138
Email: kent@bbn.com
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