ENCIPHERMENT SAFE AGAINST DPA(DIFFERENTIAL POWER ANALYSIS)

摘要

PROBLEM TO BE SOLVED: To achieve enhanced operating speed and reduction of a required RAM area by carrying out masking using a fixed value. SOLUTION: The enciphering device (300) is provided with a random number generating means to generate random numbers, a first selector (329) to select one out of q fixed values according to the random number, and a selector (329) to select one set out of q sets of fixed tables according the random number. The exclusive OR means (333) takes the exclusive OR of the fixed value and a key and the exclusive OR of input. A nonlinear transformation means (334) carries out nonlinear transformation according to a set to fixed table. Another enciphering device (500) is provided with a plurality of enciphering sections (511, 513) connected in parallel and a selector (502) to select one out of the plurality of enciphering sections according to the random number.