Extensible Authentication Protocol (EAP) Authentication Using Only a Password
RFC 5931

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Internet Engineering Task Force (IETF)                        D. Harkins
Request for Comments: 5931                                Aruba Networks
Category: Informational                                          G. Zorn
ISSN: 2070-1721                                              Network Zen
                                                             August 2010

        Extensible Authentication Protocol (EAP) Authentication
                         Using Only a Password

Abstract

   This memo describes an Extensible Authentication Protocol (EAP)
   method, EAP-pwd, which uses a shared password for authentication.
   The password may be a low-entropy one and may be drawn from some set
   of possible passwords, like a dictionary, which is available to an
   attacker.  The underlying key exchange is resistant to active attack,
   passive attack, and dictionary attack.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   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/rfc5931.

Harkins & Zorn                Informational                     [Page 1]
RFC 5931                      EAP Password                   August 2010

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   than English.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Background . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.2.  Keyword Definitions  . . . . . . . . . . . . . . . . . . .  4
     1.3.  Requirements . . . . . . . . . . . . . . . . . . . . . . .  4
       1.3.1.  Resistance to Passive Attack . . . . . . . . . . . . .  4
       1.3.2.  Resistance to Active Attack  . . . . . . . . . . . . .  5
       1.3.3.  Resistance to Dictionary Attack  . . . . . . . . . . .  5
       1.3.4.  Forward Secrecy  . . . . . . . . . . . . . . . . . . .  5
   2.  Specification of EAP-pwd . . . . . . . . . . . . . . . . . . .  5
     2.1.  Notation . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.2.  Discrete Logarithm Cryptography  . . . . . . . . . . . . .  7
       2.2.1.  Finite Field Cryptography  . . . . . . . . . . . . . .  7
       2.2.2.  Elliptic Curve Cryptography  . . . . . . . . . . . . .  8
     2.3.  Assumptions  . . . . . . . . . . . . . . . . . . . . . . .  9
     2.4.  Instantiating the Random Function  . . . . . . . . . . . .  9
     2.5.  Key Derivation Function  . . . . . . . . . . . . . . . . . 10
     2.6.  Random Numbers . . . . . . . . . . . . . . . . . . . . . . 10
     2.7.  Representation and Processing of Input Strings . . . . . . 11
       2.7.1.  Identity Strings . . . . . . . . . . . . . . . . . . . 11

Harkins & Zorn                Informational                     [Page 2]
RFC 5931                      EAP Password                   August 2010

       2.7.2.  Passwords  . . . . . . . . . . . . . . . . . . . . . . 11
     2.8.  Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 12
       2.8.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . 12
       2.8.2.  Message Flows  . . . . . . . . . . . . . . . . . . . . 12