RFC 3610 (rfc3610) - Page 1 of 26

Counter with CBC-MAC (CCM)

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Network Working Group                                         D. Whiting
Request for Comments: 3610                                          Hifn
Category: Informational                                       R. Housley
                                                          Vigil Security
                                                             N. Ferguson
                                                               MacFergus
                                                          September 2003


                       Counter with CBC-MAC (CCM)

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   Counter with CBC-MAC (CCM) is a generic authenticated encryption
   block cipher mode.  CCM is defined for use with 128-bit block
   ciphers, such as the Advanced Encryption Standard (AES).

1.  Introduction

   Counter with CBC-MAC (CCM) is a generic authenticated encryption
   block cipher mode.  CCM is only defined for use with 128-bit block
   ciphers, such as AES [AES].  The CCM design principles can easily be
   applied to other block sizes, but these modes will require their own
   specifications.

1.1.  Conventions Used In This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [STDWORDS].

2.  CCM Mode Specification

   For the generic CCM mode there are two parameter choices.  The first
   choice is M, the size of the authentication field.  The choice of the
   value for M involves a trade-off between message expansion and the
   probability that an attacker can undetectably modify a message.
   Valid values are 4, 6, 8, 10, 12, 14, and 16 octets.  The second



Whiting, et al.              Informational
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