Hybrid key exchange in TLS 1.3
draft-ietf-tls-hybrid-design-01

Document Type Active Internet-Draft (tls WG)
Authors Douglas Steblia  , Scott Fluhrer  , Shay Gueron 
Last updated 2020-10-15
Replaces draft-stebila-tls-hybrid-design
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Network Working Group                                         D. Stebila
Internet-Draft                                    University of Waterloo
Intended status: Informational                                S. Fluhrer
Expires: 18 April 2021                                     Cisco Systems
                                                               S. Gueron
                                           U. Haifa, Amazon Web Services
                                                         15 October 2020

                     Hybrid key exchange in TLS 1.3
                    draft-ietf-tls-hybrid-design-01

Abstract

   Hybrid key exchange refers to using multiple key exchange algorithms
   simultaneously and combining the result with the goal of providing
   security even if all but one of the component algorithms is broken.
   It is motivated by transition to post-quantum cryptography.  This
   document provides a construction for hybrid key exchange in the
   Transport Layer Security (TLS) protocol version 1.3.

   Discussion of this work is encouraged to happen on the TLS IETF
   mailing list tls@ietf.org or on the GitHub repository which contains
   the draft: https://github.com/dstebila/draft-ietf-tls-hybrid-design.

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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   This Internet-Draft will expire on 18 April 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Stebila, et al.           Expires 18 April 2021                 [Page 1]
Internet-Draft           ietf-tls-hybrid-design             October 2020

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   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Revision history  . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     1.3.  Motivation for use of hybrid key exchange . . . . . . . .   5
     1.4.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . .   6
     1.5.  Goals . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   2.  Key encapsulation mechanisms  . . . . . . . . . . . . . . . .   7
   3.  Construction for hybrid key exchange  . . . . . . . . . . . .   8
     3.1.  Negotiation . . . . . . . . . . . . . . . . . . . . . . .   9
     3.2.  Transmitting public keys and ciphertexts  . . . . . . . .  10
     3.3.  Shared secret calculation . . . . . . . . . . . . . . . .  11
   4.  Open questions  . . . . . . . . . . . . . . . . . . . . . . .  13
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  15
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Appendix A.  Related work . . . . . . . . . . . . . . . . . . . .  20
   Appendix B.  Design Considerations  . . . . . . . . . . . . . . .  21
     B.1.  (Neg) How to negotiate hybridization and component
           algorithms? . . . . . . . . . . . . . . . . . . . . . . .  22
       B.1.1.  Key exchange negotiation in TLS 1.3 . . . . . . . . .  23
       B.1.2.  (Neg-Ind) Negotiating component algorithms
               individually  . . . . . . . . . . . . . . . . . . . .  23
       B.1.3.  (Neg-Comb) Negotiating component algorithms as a
               combination . . . . . . . . . . . . . . . . . . . . .  24
       B.1.4.  Benefits and drawbacks  . . . . . . . . . . . . . . .  25
     B.2.  (Num) How many component algorithms to combine? . . . . .  26
       B.2.1.  (Num-2) Two . . . . . . . . . . . . . . . . . . . . .  26
       B.2.2.  (Num-2+) Two or more  . . . . . . . . . . . . . . . .  26
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