Cryptology ePrint Archive: Report 2004/048

Tail-MAC: A Message Authentication Scheme for Stream Ciphers

Bartosz Zoltak

Abstract: Tail-MAC, A predecessor to the VMPC-MAC, algorithm for computing Message Authentication Codes for stream ciphers is described along with the analysis of its security. The proposed algorithm was designed to employ some of the data already computed by the underlying stream cipher in the purpose of minimizing the computational cost of the operations required by the MAC algorithm. The performed analyses indicate several problems with the security of the scheme and lead to a new design which described in a paper "VMPC-MAC: A Stream Cipher Based Authenticated Encryption Scheme". The new scheme solves all the problems found at a cost of some compromise in the performance.

Category / Keywords: secret-key cryptography / Authenticated encryption, MAC, HMAC, stream cipher, hash function

Publication Info: Outlined at FSE 2004 Rump Session, Delhi, India, 5-7 Feb. 2004; outlined at national Polish-language, no-proceedings cryptology conference Enigma 2004, Warsaw, 11-13 May 2004

Date: received 19 Feb 2004, last revised 10 Nov 2004

Contact author: bzoltak at vmpcfunction com

Available format(s): Postscript (PS) | Compressed Postscript (PS.GZ) | PDF | BibTeX Citation

Note: Two new attacks against the Tail-MAC scheme are described. They resulted in designing a new MAC scheme "VMPC-MAC" which solves all the security problems of the Tail-MAC and is a specific scheme - dedicated only to the VMPC Stream Sipher. The new scheme is described in a paper "VMPC-MAC: A Stream Cipher Based Authenticated Encryption Scheme" available here at ePrint (2004) or at

Version: 20041111:002428 (All versions of this report)

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