Network Working Group                                         S. Farrell
Internet-Draft                                    Trinity College Dublin
Intended status: Best Current Practice                   20 October 2025
Expires: 23 April 2026

               Post-Quantum Guidance for IETF protocols.
                        draft-farrell-tls-pqg-02

Abstract

   We provide guidance on the use of post-quantum algorithms for those
   deploying applications using IETF protocols.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 23 April 2026.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Start using hybrid KEMs . . . . . . . . . . . . . . . . . . .   3
   4.  Do nothing for now on signatures  . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   3
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   [[This is not an "official" work item anywhere, the -00 was proposed
   to TLS as such, but this version generalises to more than just TLS so
   is being proposed to the secdispatch list.  The author does not
   expect that the current text will garner rough consensus, but wonders
   if we could get something useful that would without adding many
   words.  The source for this is in https://github.com/sftcd/pqg/ PRs
   are welcome there too.]]

   Due to concerns about the possible future existence of a
   cryptographically relevant quantum computer (CRQC), additional IANA
   [RFC8446] codepoints have been defined for algorithms that are hoped
   to remain secure even in the face of a CRQC.  Adding code-points for
   to the relevant IANA registries often doesn't require IETF consensus.
   This means that anyone can register code-points for their favoured
   approach.  In particular various government entities in various
   countries have made contradictory recommendations in this space,
   leading to potential confusion for those deploying applilcations
   using TLS.  For example, anyone can register a PQ algorithm in the
   TLS registries with the RECOMMENDED column set to 'n'

   This document sets out a deliberately concise set of recommendations
   for typical uses of post-quantum algorithms.  This assumes the reader
   is familiar with the topic.  Some implementations and environments
   may have to meet other requirements that conflict with this guidance.

   Note that the audience for this document are those deploying systems
   now.  This guidance is not aimed at those developing IETF protocols,
   nor implementations of those.  Given that it seems that the latter
   groups (protocol developers and implementers) seem determined to
   define and implement almost every possible combination of PQ
   everything, those deploying systems now, that have such PQ all kinds
   of everything, can benefit from simple guidance that addresses the
   most important aspect of the PQ transition.

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   It is quite likely this guidance will need to be updated with a
   short-ish period (perhaps about two years).

2.  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.

3.  Start using hybrid KEMs

   The main recommendation is to move as soon as practical to use of
   hybrid KEMs, such as X25519MLKEM768.

   Once it becomes practical to do the above, we do not recommend use of
   non-hybrid groups or "pure" PQ KEMs.

4.  Do nothing for now on signatures

   For almost all deployments, we recommend taking no action at all at
   this point in time in relation to deployment of PQ signatures.

   TODO: Define "almost all" somewhat better, but tersely.

5.  Security Considerations

   TBD

6.  Acknowledgements

   TBD

7.  IANA Considerations

   TBD, but probably not needed.

8.  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,
              <https://www.rfc-editor.org/info/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/info/rfc8174>.

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   [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/info/rfc8446>.

Author's Address

   Stephen Farrell
   Trinity College Dublin
   Dublin
   2
   Ireland
   Phone: +353-1-896-2354
   Email: stephen.farrell@cs.tcd.ie

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