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X.509 Certificate Extended Key Usage (EKU) for Instant Messaging URIs
draft-ietf-lamps-im-keyusage-01

Document Type Active Internet-Draft (lamps WG)
Author Rohan Mahy
Last updated 2024-10-15 (Latest revision 2024-10-14)
Replaces draft-mahy-lamps-im-keyusage
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
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Stream WG state Submitted to IESG for Publication
Revised I-D Needed - Issue raised by WGLC
Document shepherd Russ Housley
Shepherd write-up Show Last changed 2024-10-15
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draft-ietf-lamps-im-keyusage-01
LAMPS WG                                                         R. Mahy
Internet-Draft                            Rohan Mahy Consulting Services
Intended status: Informational                           14 October 2024
Expires: 17 April 2025

 X.509 Certificate Extended Key Usage (EKU) for Instant Messaging URIs
                    draft-ietf-lamps-im-keyusage-01

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
   mailing list (mailto:lamps@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/lamps/.  Subscribe at
   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

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

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   This Internet-Draft will expire on 17 April 2025.

Copyright Notice

   Copyright (c) 2024 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 (https://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 to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  The IM URI Extended Key Usage . . . . . . . . . . . . . . . .   3
   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 . . . . . . . . . . . . . . . . . . . . .   5
   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.  The subjectAltName of these certificates
   can be an IM URI or XMPP URI, for example.  Since IM clients could be
   very numerous, operators are reticent to issue certificates for these
   users that might accidentally be used to validate a TLS connection
   because it has the KeyPurposeId id-kp-serverAuth or id-kp-clientAuth.

   An explanation of MLS credentials as they apply to Instant Messaging
   is described in [I-D.barnes-mimi-identity-arch].  These credentials
   are expected to be heavily used in the More Instant Messaging
   Interoperability (MIMI) Working Group.

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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

   This specification defines the KeyPurposeId id-kp-imUri, which MAY be
   used for signing messages to prove the identity of an Instant
   Messaging client.  This Extended Key Usage is optionally 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 }

4.  Security Considerations

   The 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.

5.  IANA Considerations

   IANA is requested to register the following OIDs in the "SMI Security
   for PKIX Extended Key Purpose" registry (1.3.6.1.5.5.7.3).  These
   OIDs are defined in Section 4.

                  +=========+=============+============+
                  | Decimal | Description | References |
                  +=========+=============+============+
                  | TBD1    | id-kp-imUri | This-RFC   |
                  +---------+-------------+------------+

                                 Table 1

   IANA is also requested to register 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.

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                 +=========+===============+============+
                 | Decimal | Description   | References |
                 +=========+===============+============+
                 | TBD2    | id-mod-im-eku | This-RFC   |
                 +---------+---------------+------------+

                                 Table 2

6.  References

6.1.  Normative References

   [ITU.X680.2021]
              International Telecommunications Union, "Information
              Technology - Abstract Syntax Notation One (ASN.1):
              Specification of basic notation", ITU-T Recommendation
              X.680, 2021.

   [ITU.X690.2021]
              International Telecommunications Union, "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.

   [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>.

   [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>.

   [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>.

6.2.  Informative References

   [I-D.barnes-mimi-identity-arch]
              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>.

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   [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>.

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) }

   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 }

   END

   <CODE ENDS>

Appendix B.  Change log

   RFC Editor, please remove this section on publication.

   *  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

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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

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