The OPAQUE Asymmetric PAKE Protocol
draft-irtf-cfrg-opaque-03

Document Type Active Internet-Draft (cfrg RG)
Authors Hugo Krawczyk  , Kevin Lewi  , Christopher Wood 
Last updated 2021-02-21
Replaces draft-krawczyk-cfrg-opaque
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Network Working Group                                        H. Krawczyk
Internet-Draft                                       Algorand Foundation
Intended status: Informational                                   K. Lewi
Expires: 25 August 2021                                    Novi Research
                                                               C.A. Wood
                                                              Cloudflare
                                                        21 February 2021

                  The OPAQUE Asymmetric PAKE Protocol
                       draft-irtf-cfrg-opaque-03

Abstract

   This document describes the OPAQUE protocol, a secure asymmetric
   password-authenticated key exchange (aPAKE) that supports mutual
   authentication in a client-server setting without reliance on PKI and
   with security against pre-computation attacks upon server compromise.
   In addition, the protocol provides forward secrecy and the ability to
   hide the password from the server, even during password registration.
   This document specifies the core OPAQUE protocol, along with several
   instantiations in different authenticated key exchange protocols.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Source for this draft and an issue tracker can be found at
   https://github.com/cfrg/draft-irtf-cfrg-opaque.

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
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   This Internet-Draft will expire on 25 August 2021.

Krawczyk, et al.         Expires 25 August 2021                 [Page 1]
Internet-Draft                   OPAQUE                    February 2021

Copyright Notice

   Copyright (c) 2021 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
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   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Requirements Notation . . . . . . . . . . . . . . . . . .   6
     1.2.  Notation  . . . . . . . . . . . . . . . . . . . . . . . .   6
   2.  Cryptographic Protocol and Algorithm Dependencies . . . . . .   7
   3.  Offline Registration  . . . . . . . . . . . . . . . . . . . .   8
     3.1.  Credential Storage  . . . . . . . . . . . . . . . . . . .   9
     3.2.  Registration Messages . . . . . . . . . . . . . . . . . .  11
     3.3.  Registration Functions  . . . . . . . . . . . . . . . . .  12
       3.3.1.  CreateRegistrationRequest . . . . . . . . . . . . . .  12
       3.3.2.  CreateRegistrationResponse  . . . . . . . . . . . . .  12
       3.3.3.  FinalizeRequest . . . . . . . . . . . . . . . . . . .  13
       3.3.4.  Credential File . . . . . . . . . . . . . . . . . . .  15
   4.  Online Authenticated Key Exchange . . . . . . . . . . . . . .  15
     4.1.  Credential Retrieval  . . . . . . . . . . . . . . . . . .  15
       4.1.1.  Credential Retrieval Messages . . . . . . . . . . . .  16
       4.1.2.  Credential Retrieval Functions  . . . . . . . . . . .  16
     4.2.  AKE Instantiations  . . . . . . . . . . . . . . . . . . .  18
       4.2.1.  Key Schedule Utility Functions  . . . . . . . . . . .  19
       4.2.2.  OPAQUE-3DH Instantiation  . . . . . . . . . . . . . .  20
   5.  Configurations  . . . . . . . . . . . . . . . . . . . . . . .  22
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  23
     6.1.  Related Analysis  . . . . . . . . . . . . . . . . . . . .  24
     6.2.  Identities  . . . . . . . . . . . . . . . . . . . . . . .  24
     6.3.  Envelope Encryption . . . . . . . . . . . . . . . . . . .  25
     6.4.  Export Key Usage  . . . . . . . . . . . . . . . . . . . .  26
     6.5.  Static Diffie-Hellman Oracles . . . . . . . . . . . . . .  26
     6.6.  Input Validation  . . . . . . . . . . . . . . . . . . . .  26
     6.7.  OPRF Hardening  . . . . . . . . . . . . . . . . . . . . .  26
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