Internet DRAFT - draft-mahy-mls-kp-context
draft-mahy-mls-kp-context
MLS R. Mahy
Internet-Draft Wire
Intended status: Informational 22 October 2023
Expires: 24 April 2024
KeyPackage Context Extension for Message Layer Security (MLS)
draft-mahy-mls-kp-context-00
Abstract
This document describes a Message Layer Security (MLS) KeyPackage
extension to convey a specific context or anticipated use for the
KeyPackage. It is useful when a client provides the KeyPackage out-
of-band to another client, and wants the specific KeyPackage used
only in the anticipated context, for example a specific MLS group.
About This Document
This note is to be removed before publishing as an RFC.
Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-mahy-mls-kp-context/.
Discussion of this document takes place on the MLS Working Group
mailing list (mailto:mls@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/mls/. Subscribe at
https://www.ietf.org/mailman/listinfo/mls/.
Source for this draft and an issue tracker can be found at
https://github.com/rohan-wire/mls-kp-context/.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 24 April 2024.
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Copyright Notice
Copyright (c) 2023 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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Extension Description . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
4.1. kp_context MLS Extension Type . . . . . . . . . . . . . . 3
4.2. urn:ietf:mls:kp_context:group_id URN registration . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Normative References . . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Terminology
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.
The terms MLS client, MLS group, LeafNode, GroupContext, KeyPackage,
GroupContextExtensions Proposal, Credential, CredentialType, and
RequiredCapabilities have the same meanings as in the MLS protocol
[I-D.ietf-mls-protocol].
2. Introduction
In some use cases of MLS, a client might wish to provide a KeyPackage
to another client, but communicate that the specific KeyPackage is
only to be used in a specific context, for example to join a specific
MLS group. This document describes a KeyPackage extension that can
convey that context.
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3. Extension Description
This document specifies a KeyPackage MLS extension kp_context of type
ContextPair. The syntax is described using the TLS Presentation
Language [RFC8446]
Each PerDomainTrustAnchor represents a specific identity domain which
is expected and authorized to participate in the MLS group. It
contains the domain name and the specific trust anchor used to
validate identities for members in that domain.
enum {
reserved(0),
groupid(1),
uri(2),
domain(3),
jwk_thumbprint(4)
(255)
} ContextType;
struct {
ContextType context_type;
opaque context_value<V>;
} ContextPair;
ContextPair kp_context;
4. IANA Considerations
This document proposes registration of a new MLS Extension Type.
RFC EDITOR: Please replace XXXX throughout with the RFC number
assigned to this document
4.1. kp_context MLS Extension Type
The kp_context MLS Extension Type is used inside KeyPackage objects.
It contains a URN Anchors object representing the trust anchors which
are expected for identity validation inside the MLS group.
Template:
Value: 0x000B
Name: kp_context
Message(s): This extension may appear in KeyPackage objects
Recommended: Y
Reference: RFC XXXX
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4.2. urn:ietf:mls:kp_context:group_id URN registration
Namespace Identifier: Requested of IANA (formal) or assigned by IANA
(informal).
Version: 1
Date: 2023-08-01
Registrant:
Rohan Mahy
rohan.ietf@gmail.com
Purpose: Described in Section 3 of RFCXXXX.
Syntax: Described in Section 3 of RFCXXXX.
Assignment: Described in Section 4.1 of RFCXXXX.
Security and Privacy: Described in Section 5 of RFCXXXX.
Interoperability: Described in Section 3 of this document.
Resolution: Described in Section 3 of this document.
Documentation: RFCXXXX
Additional Information: none
Revision Information: n/a
5. Security Considerations
The Security Considerations of MLS apply.
The use of this extension may reveal the client's intentions or
wishes in an out-of-band protocol, which may have weaker privacy
protections than MLS handshake messages.
6. Normative References
[I-D.ietf-mls-protocol]
Barnes, R., Beurdouche, B., Robert, R., Millican, J.,
Omara, E., and K. Cohn-Gordon, "The Messaging Layer
Security (MLS) Protocol", Work in Progress, Internet-
Draft, draft-ietf-mls-protocol-20, 27 March 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-mls-
protocol-20>.
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[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>.
[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>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/rfc/rfc8446>.
Author's Address
Rohan Mahy
Wire
Email: rohan.mahy@wire.com
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