TMAC: Two-Key CBC MAC

Kaoru KUROSAWA  Tetsu IWATA 

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences  Vol.E87-A  No.1  pp.46-53
Publication Date: 2004/01/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Cipher
Keyword: 
cryptography,  CBC MAC,  block cipher,  provable security, 

Full Text: PDF(276.7KB)

Summary: 
In this paper, we propose TMAC. TMAC is a refinement of XCBC such that it requires only two keys while XCBC requires three keys. More precisely, TMAC requires only (k + n)-bit keys while XCBC requires (k + 2n)-bit keys, where k is the key length of the underlying block cipher E and n is its block length. We achieve this by using a universal hash function and the cost is almost negligible. Similar to XCBC, the domain is {0,1}* and it requires no extra invocation of E even if the size of the message is a multiple of n.