ENCRYPTION DEVICE, ENCRYPTION METHOD, AND COMPUTER PROGRAM

摘要

It is possible to realize a common key block encryption configuration capable of increasing key analysis difficulty and safety. An intermediate key generated by conversion of a secret key is stored in a register and a round key is generated by conversion of data stored in the register. The round key is generated by swap of partial data constituting the data stored in the register. For example, the data in the register is divided into four partial data so as to obtain two sets of partial data having identical number of bits. Each of the partial data is subjected to swap repeatedly so as to generate a plurality of different round keys. With this configuration, the bit arrangement of each round key is effectively exchanged and it is possible to generate round keys having a low correlation and realize a highly safe encryption which increases the key analysis difficulty.