COMPUTER CARD PREVENTED FROM BEING DUPLICATED

摘要

PROBLEM TO BE SOLVED: To compensate the indefiniteness of a ROM by an external ROM and to attain safety by simple processing. SOLUTION: When an execution program for ciphering processing such as ciphering/deciphering processing, certification processing and signature processing can not be stored in a ROM 110 built in an one-chip microcomputer 101, the program is ciphered and stored in an external ROM 106. At the time of using the program, user's qualification is checked by a certification part 103 by using ID and a password, and when the user passes the certification, the specified ciphered execution program is extracted from the storage part 106 and deciphered by a key stored in a key storage part 102 and the deciphered execution program is stored in a main memory consisting of an internal execution memory 104 and the external RAM 107 to execute the program.