Distinguishing and second-preimage attacks on CBC-like MACs

Abstract

This paper first presents a new distinguishing attack on the CBC-MAC structure based on block ciphers in cipher block chaining (CBC) mode. This attack detects a CBC-like MAC from random functions. The second result of this paper is a second-preimage attack on the CBC-MAC, which is an extension of the attack of Brincat and Mitchell. The attack also covers MT-MAC, PMAC and MACs with three-key enciphered CBC mode. Instead of exhaustive search, both types of attacks are of birthday attack complexity. © 2009 Springer-Verlag.