LAMPS WG
Internet Engineering Task Force (IETF) R. Mahy
Internet-Draft
Request for Comments: 9734 Rohan Mahy Consulting Services
Intended status:
Category: Standards Track 9 December 2024
Expires: 12 June February 2025
ISSN: 2070-1721
X.509 Certificate Extended Key Usage (EKU) for Instant Messaging URIs
draft-ietf-lamps-im-keyusage-04
Abstract
RFC 5280 specifies several extended key purpose identifiers
(KeyPurposeIds) for X.509 certificates. This document defines
Instant Messaging (IM) identity KeyPurposeId for inclusion in the
Extended Key Usage (EKU) extension of X.509 v3 public key
certificates
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at
https://rohanmahy.github.io/mahy-lamps-im-keyusage/draft-ietf-lamps-
im-keyusage.html. Status information for this document may be found
at https://datatracker.ietf.org/doc/draft-ietf-lamps-im-keyusage/.
Discussion of this document takes place on the LAMPS WG Working Group
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Source for this draft and an issue tracker can be found at
https://github.com/rohanmahy/mahy-lamps-im-keyusage.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. The IM URI Extended Key Usage . . . . . . . . . . . . . . . . 3 EKU
4. Security Considerations . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . 4
6.2. Informative References . . . . . . . . . . . . . . . . . 4
Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 5
Appendix B. Change log . . . . . . . . . . . . . . . . . . . . . 6
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Instant Messaging (IM) systems using the Messaging Layer Security
(MLS) [RFC9420] protocol can incorporate per-client identity
certificate credentials. A subjectAltName in these certificates can
be an IM URI [RFC3860] or XMPP Extensible Messaging and Presence Protocol
(XMPP) URI [RFC6121], for example.
Organizations may be unwilling to issue certificates for Instant
Message an IM client
using a general KeyPurposeId KeyPurposeId, such as id-kp-serverAuth or id-kp-clientAuth, id-kp-
clientAuth, because of the risk that such certificates could be
abused in a cross-protocol attack.
An explanation of MLS credentials as they apply to Instant Messaging IM is described in [I-D.barnes-mimi-identity-arch].
[E2E-IDENTITY]. These credentials are expected to be heavily used in
the More Instant Messaging Interoperability (MIMI) Working Group.
2. Conventions and Definitions
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
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. The IM URI Extended Key Usage EKU
This specification defines the KeyPurposeId id-kp-imUri, which may be
included in certificates used to prove the identity of an Instant
Messaging IM client.
This EKU extension MAY, at the option of the certificate issuer, be
either critical or non-critical.
id-kp OBJECT IDENTIFIER ::= {
iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) kp(3) }
id-kp-imUri OBJECT IDENTIFIER ::= { id-kp TBD1 40 }
4. Security Considerations
The Security Considerations security considerations of [RFC5280] are applicable to this
document. This extended key purpose does not introduce new security
risks but instead reduces existing security risks by providing means
to identify if the certificate is generated to sign IM identity
credentials. Issuers SHOULD NOT set the id-kp-imUri extended key
purpose and an id-kp-clientAuth or id-kp-serverAuth extended key
purpose, as
purpose: that would defeat the improved specificity offered by having
an id-kp-imUri extended key purpose.
5. IANA Considerations
IANA is requested to register has registered the following OIDs OID in the "SMI Security for PKIX
Extended Key Purpose" registry (1.3.6.1.5.5.7.3). These
OIDs are This OID is
defined in Section 4.
+=========+=============+============+
| Decimal | Description | References |
+=========+=============+============+
| TBD1 40 | id-kp-imUri | This-RFC RFC 9734 |
+---------+-------------+------------+
Table 1
IANA is has also requested to register registered the following ASN.1 [ITU.X690.2021] module
OID in the "SMI Security for PKIX Module Identifier" registry
(1.3.6.1.5.5.7.0). This OID is defined in Appendix A.
+=========+===============+============+
| Decimal | Description | References |
+=========+===============+============+
| TBD2 113 | id-mod-im-eku | This-RFC RFC 9734 |
+---------+---------------+------------+
Table 2
6. References
6.1. Normative References
[ITU.X680.2021]
International Telecommunications Union,
ITU-T, "Information Technology - Abstract Syntax Notation
One (ASN.1): Specification of basic notation", ITU-T
Recommendation X.680, 2021. ISO/IEC 8824-1:2021, February 2021,
<https://www.itu.int/rec/T-REC-X.680>.
[ITU.X690.2021]
International Telecommunications Union,
ITU-T, "Information Technology - ASN.1 encoding rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER)", ITU-T Recommendation X.690, 2021. ISO/IEC 8825-1-2021,
February 2021, <https://www.itu.int/rec/T-REC-X.690>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
<https://www.rfc-editor.org/info/rfc2119>.
[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,
<https://www.rfc-editor.org/rfc/rfc5280>.
<https://www.rfc-editor.org/info/rfc5280>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. <https://www.rfc-editor.org/info/rfc8174>.
6.2. Informative References
[I-D.barnes-mimi-identity-arch]
[E2E-IDENTITY]
Barnes, R. and R. Mahy, "Identity for E2E-Secure
Communications", Work in Progress, Internet-Draft, draft-
barnes-mimi-identity-arch-01, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-barnes-mimi-
identity-arch-01>.
[RFC3860] Peterson, J., "Common Profile for Instant Messaging
(CPIM)", RFC 3860, DOI 10.17487/RFC3860, August 2004,
<https://www.rfc-editor.org/rfc/rfc3860>.
<https://www.rfc-editor.org/info/rfc3860>.
[RFC6121] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Instant Messaging and Presence",
RFC 6121, DOI 10.17487/RFC6121, March 2011,
<https://www.rfc-editor.org/rfc/rfc6121>.
<https://www.rfc-editor.org/info/rfc6121>.
[RFC9420] Barnes, R., Beurdouche, B., Robert, R., Millican, J.,
Omara, E., and K. Cohn-Gordon, "The Messaging Layer
Security (MLS) Protocol", RFC 9420, DOI 10.17487/RFC9420,
July 2023, <https://www.rfc-editor.org/rfc/rfc9420>. <https://www.rfc-editor.org/info/rfc9420>.
Appendix A. ASN.1 Module
The following module adheres to ASN.1 specifications [ITU.X680.2021]
and [ITU.X690.2021].
<CODE BEGINS>
IM-EKU
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-im-eku (TBD2) (113) }
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
-- OID Arc
id-kp OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) kp(3) }
-- Extended Key Usage Values
id-kp-imUri OBJECT IDENTIFIER ::= { id-kp TBD1 40 }
END
<CODE ENDS>
Appendix B. Change log
RFC Editor, please remove this section on publication.
* made Proposed Standard
* added a MAY statement in Section 3
* corrected typo in registration of the ASN.1 module (Thanks Sean!)
* updated author affiliation
* added ASN.1 module
* specified that eku is optionally critical
Acknowledgments
Thanks to Sean Turner and Russ Housley for reviews, suggestions,
corrections, and encouragement.
Author's Address
Rohan Mahy
Rohan Mahy Consulting Services
Email: rohan.ietf@gmail.com