Cryptology ePrint Archive: Report 2002/180

OMAC: One-Key CBC MAC

Tetsu Iwata and Kaoru Kurosawa

Abstract: In this paper, we present One-key CBC MAC (OMAC) and prove its security for arbitrary length messages. OMAC takes only one key, $K$ ($k$ bits) of a block cipher $E$. Previously, XCBC requires three keys, $(k+2n)$ bits in total, and TMAC requires two keys, $(k+n)$ bits in total, where $n$ denotes the block length of $E$.

The saving of the key length makes the security proof of OMAC substantially harder than those of XCBC and TMAC.

Category / Keywords: secret-key cryptography / CBC MAC, block cipher, provable security

Publication Info: Pre-proceedings of FSE 2003

Date: received 25 Nov 2002, last revised 9 Mar 2003

Contact author: iwata at cis ibaraki ac jp

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Version: 20030310:075529 (All versions of this report)

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