CLIENT/SERVER SYSTEM, AND ENCIPHERED COMMUNICATION METHOD AND PROGRAM FOR CLIENT/SERVER SYSTEM

摘要

PROBLEM TO BE SOLVED: To secure security of communication between a client and a server without greatly increasing the number of cryptographic keys, which has to be mounted on clients.;SOLUTION: A client 10 has a plurality of kinds of previously stored deciphering keys 1 to 3. A client 110 has a plurality of kinds of previously stored deciphering keys 7 to 9. A plurality of kinds of cryptographic keys 1 to 9 are previously stored in a key storage section of a server 20. The set of cryptographic keys that the server 20 has cover all cryptographic keys corresponding to the deciphering keys that the clients 10 and 110 have. When the client 10 or 110 requests downloading of data to the server 20, the client states a deciphering key management number set 12 or 112 indicating the set of deciphering keys that the client has to the server 20. The server selects one deciphering key from the set of deciphering keys corresponding to the stated deciphering key to decipher information.;COPYRIGHT: (C)2006,JPO&NCIPI