Efficient Augmented Password-Only Authentication and Key Exchange for IKEv2
RFC 6628

Internet Engineering Task Force (IETF)                           S. Shin
Request for Comments: 6628                                     K. Kobara
Category: Experimental                                              AIST
ISSN: 2070-1721                                                June 2012

          Efficient Augmented Password-Only Authentication and
                         Key Exchange for IKEv2

Abstract

   This document describes an efficient augmented password-only
   authentication and key exchange (AugPAKE) protocol where a user
   remembers a low-entropy password and its verifier is registered in
   the intended server.  In general, the user password is chosen from a
   small set of dictionary words that allows an attacker to perform
   exhaustive searches (i.e., off-line dictionary attacks).  The AugPAKE
   protocol described here is secure against passive attacks, active
   attacks, and off-line dictionary attacks (on the obtained messages
   with passive/active attacks), and also provides resistance to server
   compromise (in the context of augmented PAKE security).  In addition,
   this document describes how the AugPAKE protocol is integrated into
   the Internet Key Exchange Protocol version 2 (IKEv2).

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  This document is a product of the Internet Engineering
   Task Force (IETF).  It represents the consensus of the IETF
   community.  It has received public review and has been approved for
   publication by the Internet Engineering Steering Group (IESG).  Not
   all documents approved by the IESG are a candidate for any level of
   Internet Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6628.

Shin & Kobara                 Experimental                      [Page 1]
RFC 6628         Most Efficient Augmented PAKE for IKEv2       June 2012

Copyright Notice

   Copyright (c) 2012 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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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
      1.1. Keywords ...................................................4
   2. AugPAKE Specification ...........................................4
      2.1. Underlying Group ...........................................4
      2.2. Notation ...................................................5
           2.2.1. Password Processing .................................6
      2.3. Protocol ...................................................7
           2.3.1. Initialization ......................................7
           2.3.2. Actual Protocol Execution ...........................7
   3. Security Considerations .........................................9
      3.1. General Assumptions ........................................9
      3.2. Security against Passive Attacks ..........................10
      3.3. Security against Active Attacks ...........................10
           3.3.1. Impersonation Attacks on User U ....................10
           3.3.2. Impersonation Attacks on Server S ..................11
           3.3.3. Man-in-the-Middle Attacks ..........................11
      3.4. Security against Off-line Dictionary Attacks ..............12
      3.5. Resistance to Server Compromise ...........................12
   4. Implementation Consideration ...................................13
   5. AugPAKE for IKEv2 ..............................................13
      5.1. Integration into IKEv2 ....................................13
      5.2. Payload Formats ...........................................15
           5.2.1. Notify Payload .....................................15
           5.2.2. Generic Secure Password Method Payload .............16
   6. IANA Considerations ............................................16
   7. References .....................................................16
      7.1. Normative References ......................................16