Patent ID: 8457306

Claim:
A cryptographic module that performs a cryptographic operation, the cryptographic module comprising: a first input terminal to which data related to input data to be used in the cryptographic operation is inputted; first and second registers that respectively retain first and second data obtained by dividing the data inputted to the first input terminal; a second input terminal to which in inputted data that is independent of the first data and that is unrelated to the cryptographic operation and that is random; third and fourth registers that respectively retain third and fourth data obtained by dividing the data inputted to the second input terminal; a selection circuit that alternately selects the first data and the third data, outputs the selected data to the first register and the third register so that the first data and the third data are alternately retained in the first register and the third register in the cryptographic operation, and alternately selects the second data and the fourth data, and outputs the selected data to the second register and the fourth register so that the second data and the fourth data are alternately retained in the second register and the further register in the cryptographic operation; and an operational circuit that performs a predetermined operations on data respectively outputted from the first, second, third and fourth registers.