Usage of OPAQUE with TLS 1.3
draft-sullivan-tls-opaque-00

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Network Working Group                                        N. Sullivan
Internet-Draft                                                Cloudflare
Intended status: Standards Track                             H. Krawczyk
Expires: September 12, 2019                                 IBM Research
                                                                O. Friel
                                                               R. Barnes
                                                                   Cisco
                                                          March 11, 2019

                      Usage of OPAQUE with TLS 1.3
                      draft-sullivan-tls-opaque-00

Abstract

   This document describes two mechanisms for enabling the use of the
   OPAQUE password-authenticated key exchange in TLS 1.3.

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 September 12, 2019.

Copyright Notice

   Copyright (c) 2019 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
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Sullivan, et al.       Expires September 12, 2019               [Page 1]
Internet-Draft               TLS 1.3 OPAQUE                   March 2019

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  OPAQUE  . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Password Registration . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Implementing EnvU . . . . . . . . . . . . . . . . . . . .   5
   5.  TLS extensions  . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Use of extensions in TLS handshake flows  . . . . . . . . . .   8
     6.1.  OPAQUE-3DH, OPAQUE-HMQV . . . . . . . . . . . . . . . . .   8
     6.2.  OPAQUE-Sign . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  Integration into Exported Authenticators  . . . . . . . . . .  11
   8.  Summary of properties . . . . . . . . . . . . . . . . . . . .  11
   9.  Example OPRF  . . . . . . . . . . . . . . . . . . . . . . . .  12
     9.1.  OPRF_1  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     9.2.  OPRF_2  . . . . . . . . . . . . . . . . . . . . . . . . .  13
   10. Privacy considerations  . . . . . . . . . . . . . . . . . . .  13
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  14
   12. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     13.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Note that this draft has not received significant security review and
   should not be the basis for production systems.

   OPAQUE [opaque-paper] is a mutual authentication method that enables
   the establishment of an authenticated cryptographic key between a
   client and server based on a user's memorized password, without ever
   exposing the password to servers or other entities other than the
   client machine and without relying on PKI.  OPAQUE leverages a
   primitive called a Strong Asymmetrical Password Authenticated Key
   Exchange (Strong aPAKE) to provide desirable properties including
   resistance to pre-computation attacks in the event of a server
   compromise.

   In some cases, it is desirable to combine password-based
   authentication with traditional PKI-based authentication as a
   defense-in-depth measure.  For example, in the case of IoT devices,
   it may be useful to validate that both parties were issued a