| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a communication system in which a problem of processing time required for sharing a key is solved. <P>SOLUTION: In the communication system, when downloading a program, an application key is transferred from a center 100 to a card terminal 200 and shared (S303 and S304) and when running the program, a counter value is transferred from the card terminal 200 to the center 100 and shared (S306). Then, the card terminal 200 and the center 100 respectively produce common keys from the counter value and the application key (S307 and S310). <P>COPYRIGHT: (C)2004,JPO |
