| 摘要 |
PROBLEM TO BE SOLVED: To provide a modular exponentiation arithmetic unit, an IC card, a modular exponentiation arithmetic method, and a modular exponentiation arithmetic program so as to be capable of effectively dealing with an attack such as "Bypass Fault Attack".SOLUTION: A modular exponentiation arithmetic unit counts, when a public key index e is expressed as a binary digit representation e(k(bit length of e)>i≥0) and while repeating operations consisting of k times square residue arithmetics and the number of bits times multiplication remainder arithmetics to be e=1, the times of operations of the square residue arithmetics or the multiplication remainder arithmetics, compares the counted times of operations with a predetermined number of times, determines whether it is abnormal or not on the basis of the comparison result, and performs an error processing if it is determined to be abnormal. |
