US Patent 11177936 Message authenticator generation apparatus

A message authenticator generation apparatus (10) generates a message authenticator using a block cipher E having a block size n. A hash function unit (21) calculates a hash value w with a hash function h having an output length longer than n bits, taking as input a message M. A post-processing unit (22) performs calculations using the block cipher E on the hash value w calculated by the hash function unit (21), so as to calculate a message authenticator T not larger than the block size n for the message M.