DEVICE AND METHOD FOR CIPHERING, AND DEVICE AND METHOD FOR TRANSMISSION AND RECEPTION

摘要

PROBLEM TO BE SOLVED: To make it difficult to decipher the key of a ciphering device. SOLUTION: An expanded key generating circuit 400 generates 16 expanded keys in total from a 64-bit secret key and stores them in a memory 401 in order. An address generating circuit 402 generates prescribed address data according to input data. Then an expanded key stored in an address specified with the generated address data is read out of the memory 401 and supplied to an (f) function circuit 150-1. The (f) function circuit 150-1 performs a prescribed operation between the input data and the expanded key supplied from the address generating circuit 402 outputs obtained data.