New Bounds for PMAC, TMAC, and XCBC

We provide new security proofs for PMAC, TMAC, and XCBC message authentication modes. The previous security bounds for these modes were σ2 /2n , where n is the block size in bits and σ is the total number of queried message blocks. Our new bounds are q2 /2n for PMAC and q2 /2n + 4 q2 /22n for TMAC and XCBC, where q is the number of queries and is the maximum message length in n-bit blocks. This improves the previous results under most practical cases, e.g., when no message is exceptionally long compared to other messages.

• Type: Conference
• Year: 2007
• Where: FSE
• Authors: Kazuhiko Minematsu, Toshiyasu Matsushima
• Keywords: Cryptography, FSE 2007, Maximum Message Length, Message Authentication Modes, Message Blocks