| 摘要 |
PURPOSE: To provide an information recording medium capable of surely detecting illegal use or data alteration and having extremely high security. CONSTITUTION: An external processor 2 reads out the ID code P1 of an information recording medium 1, a transaction count value P2 and stored data P. Diversification function part 23 prepares a diversification key K' based upon the 10 code P1, the count value P2 and a cipher key K and a ciphering function part 24 prepares validity information based upon the key K' and the stored data P and compares the prepared information with validity information read out from the medium 1. When the medium 1 is valid and illegal action is not executed, the contents of both the information coincide with each other, so that the existence of illegarity or alteration can be surely judged. |
