Paper 2004/048

Tail-MAC: A Message Authentication Scheme for Stream Ciphers

Bartosz Zoltak


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.

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

Available format(s)
Secret-key cryptography
Publication info
Published elsewhere. 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
Authenticated encryptionMACHMACstream cipherhash function
Contact author(s)
bzoltak @ vmpcfunction com
2004-11-11: last of 4 revisions
2004-02-21: received
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Creative Commons Attribution


      author = {Bartosz Zoltak},
      title = {Tail-{MAC}: A Message Authentication Scheme for Stream Ciphers},
      howpublished = {Cryptology ePrint Archive, Paper 2004/048},
      year = {2004},
      note = {\url{}},
      url = {}
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