ENCIPHERING CIRCUIT PROVIDED WITH TAMPER RESISTANCE FUNCTION

摘要

PROBLEM TO BE SOLVED: To make tamper resistance and power conservation compatible in an enciphering circuit such as a portable terminal, etc. SOLUTION: An internal storage means 2 keeps secret data. A means for randomizing arithmetic order, a means for obtaining a correct value by concealing arithmetic data itself by a random number an removing the random number after calculation or a means for adding random noise in the case of calculation, etc., is adopted as a tampering resistance means 5. A control means 1 changes over the tamper resistance means 5 so as to automatically turning on the means 5 in the case of calculation using secret data of the storage means 2 and not to operate the means 5 unless secret data is used.