| 摘要 |
PROBLEM TO BE SOLVED: To provide a ciphering device, a deciphering device, and a ciphering and deciphering device having resistant property against deciphering analysis by means of measurement of electric power consumption such as electric power analysis and electric power differentiating analysis. SOLUTION: An intermediate data control means 123, by using a random number outputted from a random number generator 140 as an input, executes a random number dependent intermediate data change operation to change intermediate data depending on the random number at the time of generation of an intermediate data change request, and controls to offset an effect of the random number by applying the random number dependent intermediate data change requests for a plurality of times. A ciphering operation means 121, by changing its state depending on the random number dependent intermediate data change operation, executes a ciphering process for usual sentences, outputs a ciphered sentence not depending on the random number. A random number dependent deciding means 122 issues the intermediate data change request when judging that the present processing stage of the ciphering process is the processing stage to apply the random number dependent intermediate data change operation.
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