Mutual authentication system.

摘要

When mutual authentication is effected between an IC card (1) and a host device (8), key data and random number data transmitted from the host device (8) are immediately subjected to the encrypting process without storing the same into a RAM of a CPU (15) in the IC card (1), and only authentication data obtained as the result of the encrypting process is stored. As a result, the memory area in the RAM can be saved and effectively used.