Network Working Group K. Kohbrok Internet-Draft Phoenix R&D Intended status: Informational F. Kiefer Expires: 3 April 2023 Cryspen S. Nandakumar Cisco 30 September 2022 The Messaging Layer Security (MLS) Implementation Considerations draft-kohbrok-mls-implementation-considerations-latest Abstract The MLS protocol is a large and complex security protocol. In this document, we provide guidance and recommendations for implementers of MLS regarding correctness, security, efficiency and robustness. Discussion Venues This note is to be removed before publishing as an RFC. Discussion of this document takes place on the Messaging Layer Security Working Group mailing list (mls@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/mls/. Source for this draft and an issue tracker can be found at https://github.com/kkohbrok/mls-implementation-considerations. 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." This Internet-Draft will expire on 3 April 2023. Copyright Notice Copyright (c) 2022 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. Conventions and Definitions 3. Security Considerations 4. IANA Considerations 5. References 5.1. Normative References 5.2. Informative References Acknowledgments Authors' Addresses 1. Introduction Implementing the specification of a complex security protocol in a correct and secure manner is a challenging task. This document aims to provide guidance to implementers of the Messaging Layer Security (MLS) protocol specification [I-D.ietf-mls-protocol] in a variety of ways. The goal of this document is also to extend the existing guidance given in the MLS architecture document [I-D.ietf-mls-architecture] on how to use MLS securely in a larger context. Finally, this document is also meant to provide examples on how to fill several of the gaps that the protocol specification and architective document have left open, but that are likely going to be needed by a large number of MLS users. 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. Security Considerations TODO Security 4. IANA Considerations This document has no IANA actions. 5. References 5.1. 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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 5.2. Informative References [I-D.ietf-mls-architecture] Beurdouche, B., Rescorla, E., Omara, E., Inguva, S., Kwon, A., and A. Duric, "The Messaging Layer Security (MLS) Architecture", Work in Progress, Internet-Draft, draft- ietf-mls-architecture-09, 19 August 2022, . [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-16, 11 July 2022, . Acknowledgments TODO acknowledge. Authors' Addresses Konrad Kohbrok Phoenix R&D Email: konrad@phnx.im Franziskus Kiefer Cryspen Email: franziskuskiefer@gmail.com Suhas Nandakumar Cisco Email: snandaku@cisco.com