Encryption apparatus and encryption method

摘要

An encryption apparatus for generating a ciphertext block from a plaintext block is disclosed. A selector selects at random one mask random number from a plurality of random numbers generated by a random number generator. A mask processing unit executes mask processing of a plaintext block by using the mask random number selected by the selector. A storage unit stores a first table representing an initial S-box. A converter converts the first table into a second table representing a deformed S-box on the basis of the mask random number selected by the selector. An encryption unit generates a ciphertext block by shuffling the mask-processed plaintext block using the second table.