| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit device for decoding and executing an enciphered program without requiring installation of a non-volatile memory for holding a decoding program, and also preventing the decoded program from not being observed from an outer part. <P>SOLUTION: When the enciphered program and the decoding program D123a are inputted to a RAM 105, the semiconductor integrated circuit device 101 prohibits access to a bus port 110a from the outer part, permits access to the RAM 104 and 105, and transfers the enciphered program and the decoding program to the RAM 105. When the transfer is completed, access to the RAM 104 is prohibited. Then a CPU 103a is instructed to decode the enciphered program through the use of a secret key held in a secret key holding part 107, and the decoding program D123a, and also to execute the decoded program. After the performance of the program is completed, access to the RAM 105 is prohibited. <P>COPYRIGHT: (C)2004,JPO</p> |
