rfc9734.original   rfc9734.txt 
LAMPS WG R. Mahy Internet Engineering Task Force (IETF) R. Mahy
Internet-Draft Rohan Mahy Consulting Services Request for Comments: 9734 Rohan Mahy Consulting Services
Intended status: Standards Track 9 December 2024 Category: Standards Track February 2025
Expires: 12 June 2025 ISSN: 2070-1721
X.509 Certificate Extended Key Usage (EKU) for Instant Messaging URIs X.509 Certificate Extended Key Usage (EKU) for Instant Messaging URIs
draft-ietf-lamps-im-keyusage-04
Abstract Abstract
RFC 5280 specifies several extended key purpose identifiers RFC 5280 specifies several extended key purpose identifiers
(KeyPurposeIds) for X.509 certificates. This document defines (KeyPurposeIds) for X.509 certificates. This document defines an
Instant Messaging (IM) identity KeyPurposeId for inclusion in the Instant Messaging (IM) identity KeyPurposeId for inclusion in the
Extended Key Usage (EKU) extension of X.509 v3 public key Extended Key Usage (EKU) extension of X.509 v3 public key
certificates 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
mailing list (mailto:lamps@ietf.org), which is archived at
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https://www.ietf.org/mailman/listinfo/lamps/.
Source for this draft and an issue tracker can be found at
https://github.com/rohanmahy/mahy-lamps-im-keyusage.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is a product of the Internet Engineering Task Force
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Internet Standards is available in Section 2 of RFC 7841.
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This Internet-Draft will expire on 12 June 2025.
Copyright Notice Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3 2. Conventions and Definitions
3. The IM URI Extended Key Usage . . . . . . . . . . . . . . . . 3 3. The IM URI EKU
4. Security Considerations . . . . . . . . . . . . . . . . . . . 3 4. Security Considerations
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. IANA Considerations
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 6. References
6.1. Normative References . . . . . . . . . . . . . . . . . . 4 6.1. Normative References
6.2. Informative References . . . . . . . . . . . . . . . . . 4 6.2. Informative References
Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 5 Appendix A. ASN.1 Module
Appendix B. Change log . . . . . . . . . . . . . . . . . . . . . 6 Acknowledgments
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6 Author's Address
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
Instant Messaging (IM) systems using the Messaging Layer Security Instant Messaging (IM) systems using the Messaging Layer Security
(MLS) [RFC9420] protocol can incorporate per-client identity (MLS) [RFC9420] protocol can incorporate per-client identity
certificate credentials. A subjectAltName in these certificates can certificate credentials. A subjectAltName in these certificates can
be an IM URI [RFC3860] or XMPP URI [RFC6121], for example. be an IM URI [RFC3860] or Extensible Messaging and Presence Protocol
(XMPP) URI [RFC6121], for example.
Organizations may be unwilling to issue certificates for Instant Organizations may be unwilling to issue certificates for an IM client
Message client using a general KeyPurposeId such as id-kp-serverAuth using a general KeyPurposeId, such as id-kp-serverAuth or id-kp-
or id-kp-clientAuth, because of the risk that such certificates could clientAuth, because of the risk that such certificates could be
be abused in a cross-protocol attack. abused in a cross-protocol attack.
An explanation of MLS credentials as they apply to Instant Messaging An explanation of MLS credentials as they apply to IM is described in
is described in [I-D.barnes-mimi-identity-arch]. These credentials [E2E-IDENTITY]. These credentials are expected to be heavily used in
are expected to be heavily used in the More Instant Messaging the More Instant Messaging Interoperability (MIMI) Working Group.
Interoperability (MIMI) Working Group.
2. Conventions and Definitions 2. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. The IM URI Extended Key Usage 3. The IM URI EKU
This specification defines the KeyPurposeId id-kp-imUri, which may be This specification defines the KeyPurposeId id-kp-imUri, which may be
included in certificates used to prove the identity of an Instant included in certificates used to prove the identity of an IM client.
Messaging client. This EKU extension MAY, at the option of the This EKU extension MAY, at the option of the certificate issuer, be
certificate issuer, be either critical or non-critical. either critical or non-critical.
id-kp OBJECT IDENTIFIER ::= { id-kp OBJECT IDENTIFIER ::= {
iso(1) identified-organization(3) dod(6) internet(1) iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) kp(3) } security(5) mechanisms(5) pkix(7) kp(3) }
id-kp-imUri OBJECT IDENTIFIER ::= { id-kp TBD1 } id-kp-imUri OBJECT IDENTIFIER ::= { id-kp 40 }
4. Security Considerations 4. Security Considerations
The Security Considerations of [RFC5280] are applicable to this The security considerations of [RFC5280] are applicable to this
document. This extended key purpose does not introduce new security document. The id-kp-imUri extended key purpose does not introduce
risks but instead reduces existing security risks by providing means new security risks but instead reduces existing security risks by
to identify if the certificate is generated to sign IM identity providing means to identify if the certificate is generated to sign
credentials. Issuers SHOULD NOT set the id-kp-imUri extended key IM identity credentials. Issuers SHOULD NOT set the id-kp-imUri
purpose and an id-kp-clientAuth or id-kp-serverAuth extended key extended key purpose and an id-kp-clientAuth or id-kp-serverAuth
purpose, as that would defeat the improved specificity offered by extended key purpose: that would defeat the improved specificity
having an id-kp-imUri extended key purpose. offered by having an id-kp-imUri extended key purpose.
5. IANA Considerations 5. IANA Considerations
IANA is requested to register the following OIDs in the "SMI Security IANA has registered the following OID in the "SMI Security for PKIX
for PKIX Extended Key Purpose" registry (1.3.6.1.5.5.7.3). These Extended Key Purpose" registry (1.3.6.1.5.5.7.3). This OID is
OIDs are defined in Section 4. defined in Section 3.
+=========+=============+============+ +=========+=============+============+
| Decimal | Description | References | | Decimal | Description | References |
+=========+=============+============+ +=========+=============+============+
| TBD1 | id-kp-imUri | This-RFC | | 40 | id-kp-imUri | RFC 9734 |
+---------+-------------+------------+ +---------+-------------+------------+
Table 1 Table 1
IANA is also requested to register the following ASN.1 IANA has also registered the following ASN.1 [ITU.X690.2021] module
[ITU.X690.2021] module OID in the "SMI Security for PKIX Module OID in the "SMI Security for PKIX Module Identifier" registry
Identifier" registry (1.3.6.1.5.5.7.0). This OID is defined in (1.3.6.1.5.5.7.0). This OID is defined in Appendix A.
Appendix A.
+=========+===============+============+ +=========+===============+============+
| Decimal | Description | References | | Decimal | Description | References |
+=========+===============+============+ +=========+===============+============+
| TBD2 | id-mod-im-eku | This-RFC | | 113 | id-mod-im-eku | RFC 9734 |
+---------+---------------+------------+ +---------+---------------+------------+
Table 2 Table 2
6. References 6. References
6.1. Normative References 6.1. Normative References
[ITU.X680.2021] [ITU.X680.2021]
International Telecommunications Union, "Information ITU-T, "Information Technology - Abstract Syntax Notation
Technology - Abstract Syntax Notation One (ASN.1): One (ASN.1): Specification of basic notation", ITU-T
Specification of basic notation", ITU-T Recommendation Recommendation X.680, ISO/IEC 8824-1:2021, February 2021,
X.680, 2021. <https://www.itu.int/rec/T-REC-X.680>.
[ITU.X690.2021] [ITU.X690.2021]
International Telecommunications Union, "Information ITU-T, "Information Technology - ASN.1 encoding rules:
Technology - ASN.1 encoding rules: Specification of Basic Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (BER), Canonical Encoding Rules (CER) and Encoding Rules (CER) and Distinguished Encoding Rules
Distinguished Encoding Rules (DER)", ITU-T Recommendation (DER)", ITU-T Recommendation X.690, ISO/IEC 8825-1-2021,
X.690, 2021. February 2021, <https://www.itu.int/rec/T-REC-X.690>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, 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., [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, (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 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
6.2. Informative References 6.2. Informative References
[I-D.barnes-mimi-identity-arch] [E2E-IDENTITY]
Barnes, R. and R. Mahy, "Identity for E2E-Secure Barnes, R. and R. Mahy, "Identity for E2E-Secure
Communications", Work in Progress, Internet-Draft, draft- Communications", Work in Progress, Internet-Draft, draft-
barnes-mimi-identity-arch-01, 23 October 2023, barnes-mimi-identity-arch-02, 4 February 2025,
<https://datatracker.ietf.org/doc/html/draft-barnes-mimi- <https://datatracker.ietf.org/doc/html/draft-barnes-mimi-
identity-arch-01>. identity-arch-02>.
[RFC3860] Peterson, J., "Common Profile for Instant Messaging [RFC3860] Peterson, J., "Common Profile for Instant Messaging
(CPIM)", RFC 3860, DOI 10.17487/RFC3860, August 2004, (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 [RFC6121] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Instant Messaging and Presence", Protocol (XMPP): Instant Messaging and Presence",
RFC 6121, DOI 10.17487/RFC6121, March 2011, 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., [RFC9420] Barnes, R., Beurdouche, B., Robert, R., Millican, J.,
Omara, E., and K. Cohn-Gordon, "The Messaging Layer Omara, E., and K. Cohn-Gordon, "The Messaging Layer
Security (MLS) Protocol", RFC 9420, DOI 10.17487/RFC9420, Security (MLS) Protocol", RFC 9420, DOI 10.17487/RFC9420,
July 2023, <https://www.rfc-editor.org/rfc/rfc9420>. July 2023, <https://www.rfc-editor.org/info/rfc9420>.
Appendix A. ASN.1 Module Appendix A. ASN.1 Module
The following module adheres to ASN.1 specifications [ITU.X680.2021] The following module adheres to ASN.1 specifications [ITU.X680.2021]
and [ITU.X690.2021]. and [ITU.X690.2021].
<CODE BEGINS> <CODE BEGINS>
IM-EKU IM-EKU
{ iso(1) identified-organization(3) dod(6) internet(1) { iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0) security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-im-eku (TBD2) } id-mod-im-eku (113) }
DEFINITIONS IMPLICIT TAGS ::= DEFINITIONS IMPLICIT TAGS ::=
BEGIN BEGIN
-- OID Arc -- OID Arc
id-kp OBJECT IDENTIFIER ::= id-kp OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1) { iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) kp(3) } security(5) mechanisms(5) pkix(7) kp(3) }
-- Extended Key Usage Values -- Extended Key Usage Values
id-kp-imUri OBJECT IDENTIFIER ::= { id-kp TBD1 } id-kp-imUri OBJECT IDENTIFIER ::= { id-kp 40 }
END END
<CODE ENDS> <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 Acknowledgments
Thanks to Sean Turner and Russ Housley for reviews, suggestions, Thanks to Sean Turner and Russ Housley for reviews, suggestions,
corrections, and encouragement. corrections, and encouragement.
Author's Address Author's Address
Rohan Mahy Rohan Mahy
Rohan Mahy Consulting Services Rohan Mahy Consulting Services
Email: rohan.ietf@gmail.com Email: rohan.ietf@gmail.com
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