ATTACKS ON FAST DOUBLE BLOCK LENGTH HASH FUNCTIONS

The security of hash functions based on a block cipher with a block le ngth of m bits and a key length of k bits, where k less than or equal to in, is considered. New attacks are presented on a large class of it erated hash functions with a am-bit hash result which processes in eac h iteration two message blocks using two encryptions. In particular, t he attacks break three proposed schemes: Parallel-DM, the PBGV hash fu nction, and the LOKI DBH mode.