Usage of PAKE with TLS 1.3
draft-barnes-tls-pake-04

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Network Working Group                                          R. Barnes
Internet-Draft                                                  O. Friel
Intended status: Informational                                     Cisco
Expires: January 17, 2019                                  July 16, 2018

                       Usage of PAKE with TLS 1.3
                        draft-barnes-tls-pake-04

Abstract

   The pre-shared key mechanism available in TLS 1.3 is not suitable for
   usage with low-entropy keys, such as passwords entered by users.
   This document describes an extension that enables the use of
   password-authenticated key exchange protocols with TLS 1.3.

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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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 17, 2019.

Copyright Notice

   Copyright (c) 2018 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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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  TLS Extensions  . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Compatible PAKE Protocols . . . . . . . . . . . . . . . . . .   5
   6.  SPAKE2+ Implementation  . . . . . . . . . . . . . . . . . . .   6
   7.  Pre-provisioned Parameters  . . . . . . . . . . . . . . . . .   6
   8.  Content of the TLS Extensions . . . . . . . . . . . . . . . .   7
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
     9.1.  Security when using SPAKE2+ . . . . . . . . . . . . . . .   8
   10. Open Items  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  PAKE Algorithm Negotiation . . . . . . . . . . . . . . .   9
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     12.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   DISCLAIMER: This is a work-in-progress draft and has not yet seen
   significant security analysis.  It should not be used as a basis for
   building production systems.

   In some applications, it is desireable to enable a client and server
   to authenticate to one another using a low-entropy pre-shared value,
   such as a user-entered password.

   In prior versions of TLS, this functionality has been provided by the
   integration of the Secure Remote Password PAKE protocol (SRP)
   [RFC5054].  The specific SRP integration described in RFC 5054 does
   not immediately extend to TLS 1.3 because it relies on the Client Key
   Exchange and Server Key Exchange messages, which no longer exist in
   1.3.

   TLS 1.3 itself provides a mechanism for authentication with pre-
   shared keys (PSKs).  However, PSKs used with this protocol need to be
   "full-entropy", because the binder values used for authentication can
   be used to mount a dictionary attack on the PSK.  So while the TLS
   1.3 PSK mechanism is suitable for the session resumption cases for
   which it is specified, it cannot be used when the client and server
   share only a low-entropy secret.

   Enabling TLS to address this use case effectively requires the TLS
   handshake to execute a password-authenticated key establishment

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   (PAKE) protocol.  This document describes a TLS extension "pake" that