ENCRYPTION PROCESSING DEVICE, ENCRYPTION PROCESSING METHOD, AND PROGRAM

PROBLEM TO BE SOLVED: To realize very safe encryption processing having improved diffusion properties.SOLUTION: One aspect of this invention comprises an encryption processing unit which divides configuration bits of data to be processed into a plurality of lines and inputs the same, and then repeatedly executes a data conversion process in which a round function is applied to the data in each line. In the encryption processing unit, n/d-bit data obtained by dividing n-bit data, which is input data, by a division number d is inputted to each line, and an operation including the data conversion process in which the round function is applied is executed as a round operation repeatedly. The n/d-bit data in a line having output data of the round operation is divided into d/2 units, and the divided data is combined to reconfigure d units of n/d-bit data differing from the output data of the round operation of the previous stage, which are used as input data for the round operation of the next stage to execute a process. This configuration can realize very safe encryption processing having improved diffusion properties.