MARS Algorithm

MARS is a block cipher that was IBM's submission to the Advanced Encryption Standard process, selected as one of five AES finalists in August 1999. Its design team included Don Coppersmith, who had also been involved in the creation of the earlier Data Encryption Standard two decades before, and the cipher was deliberately built with a layered, compartmentalized structure meant to resist future advances in cryptanalysis. MARS uses a 128-bit block size and a variable key size between 128 and 448 bits in 32-bit increments, and unlike most block ciphers it has a heterogeneous structure in which several rounds of a cryptographic core are jacketed by unkeyed mixing rounds together with key whitening.