RFC 3310 (rfc3310) - Page 2 of 18

Hypertext Transfer Protocol (HTTP) Digest Authentication Using Authentication and Key Agreement (AKA)

RFC 3310          HTTP Digest Authentication Using AKA    September 2002


Table of Contents

   1.  Introduction and Motivation  . . . . . . . . . . . . . . . . .  2
   1.1 Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.2 Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  AKA Mechanism Overview . . . . . . . . . . . . . . . . . . . .  4
   3.  Specification of Digest AKA  . . . . . . . . . . . . . . . . .  5
   3.1 Algorithm Directive  . . . . . . . . . . . . . . . . . . . . .  5
   3.2 Creating a Challenge . . . . . . . . . . . . . . . . . . . . .  6
   3.3 Client Authentication  . . . . . . . . . . . . . . . . . . . .  7
   3.4 Synchronization Failure  . . . . . . . . . . . . . . . . . . .  7
   3.5 Server Authentication  . . . . . . . . . . . . . . . . . . . .  8
   4.  Example Digest AKA Operation . . . . . . . . . . . . . . . . .  8
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   5.1 Authentication of Clients using Digest AKA . . . . . . . . . . 13
   5.2 Limited Use of Nonce Values  . . . . . . . . . . . . . . . . . 13
   5.3 Multiple Authentication Schemes and Algorithms . . . . . . . . 14
   5.4 Online Dictionary Attacks  . . . . . . . . . . . . . . . . . . 14
   5.5 Session Protection . . . . . . . . . . . . . . . . . . . . . . 14
   5.6 Replay Protection  . . . . . . . . . . . . . . . . . . . . . . 15
   5.7 Improvements to AKA Security . . . . . . . . . . . . . . . . . 15
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   6.1 Registration Template  . . . . . . . . . . . . . . . . . . . . 16
       Normative References . . . . . . . . . . . . . . . . . . . . . 16
       Informative References . . . . . . . . . . . . . . . . . . . . 16
   A.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 17
       Full Copyright Statement . . . . . . . . . . . . . . . . . . . 18

1. Introduction and Motivation

   The Hypertext Transfer Protocol (HTTP) Authentication Framework,
   described in RFC 2617 [2], includes two authentication schemes: Basic
   and Digest.  Both schemes employ a shared secret based mechanism for
   access authentication.  The Basic scheme is inherently insecure in
   that it transmits user credentials in plain text.  The Digest scheme
   improves security by hiding user credentials with cryptographic
   hashes, and additionally by providing limited message integrity.

   The Authentication and Key Agreement (AKA) [6] mechanism performs
   authentication and session key distribution in Universal Mobile
   Telecommunications System (UMTS) networks.  AKA is a challenge-
   response based mechanism that uses symmetric cryptography.  AKA is
   typically run in a UMTS IM Services Identity Module (ISIM), which
   resides on a smart card like device that also provides tamper
   resistant storage of shared secrets.





Niemi, et. al.               Informational