CRYPTOGRAPHIC CALCULATION PROCESSING CIRCUIT

摘要

There is included a camouflage calculation instructing circuit (100) that issues, as a substitute for a CPU (109) or the like, a camouflage calculation instruction (113) to a cryptology control circuit (101) in response to completion of the execution of a cryptographic calculation instruction (111) from the CPU (109) or the like. After the completion of the execution of the cryptographic calculation instruction (111), calculation resources, such as memories, a calculator, registers and so on (103-108), which usually halt, are caused to operate, resulting in current consumptions. It is, therefore, different to determine, based on whether large or small current consumptions, the timings of the start, end and so on of the cryptographic calculation process. However, the camouflage calculation instruction (113) is issued only while no cryptographic calculation instruction (111) is issued from the CPU (109) or the like, so that the performance of the cryptographic calculation is not degraded.