TAG GENERATION APPARATUS, TAG VERIFICATION APPARATUS, COMMUNICATION SYSTEM, TAG GENERATION METHOD, TAG VERIFICATION METHOD, AND RECORDING MEDIUM

摘要

The tag generation apparatus of the present invention includes a hash unit (12) that applies a hash function to a message to generate a hash value, a random number encryption unit (14) that applies an encryption function having a first key to a random number that is independent of the message to generate a first intermediate variable, a masked encryption unit (15) that applies the encryption function having a second key to the sum of the random number and the hash value to generate a second intermediate variable, and a tag generation unit (16) that generates as the tag a value contained in bits of a predetermined number of bits that is less than or equal to the number of bits of the random number and that are extracted from the exclusive OR of the first intermediate variable and the second intermediate variable.