CRYPTOGRAPHIC COMMUNICATION METHOD, CRYPTOGRAPHIC COMMUNICATION SYSTEM, COMPUTER FOR PERFORMING CRYPTOGRAPHIC COMMUNICATION, STORAGE MEDIUM AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide cryptographic communication in which high cipher strength and low processing costs are compatible by guaranteeing consistency between a transmitting side and a receiving side for an encipher/decipher algorithm and enabling frequent changes.;SOLUTION: A decipher algorithm D1 corresponding to an encipher algorithm C1 is enciphered and transmitted from the transmitting side to the receiving side by an encipher algorithm A of high strength and on the receiving side, this is deciphered by a decipher algorithm B corresponding to the algorithm A. Afterwards, transmission object data Ex are enciphered and transmitted from the transmitting side by C1 and on the receiving side, these data are deciphered by D1. On the other hand, on the transmitting side, decipher algorithms D2, D3,... corresponding to the encipher algorithms C2, C3,... are transmitted in an appropriate timing. Then, the transmission object data Ex are enciphered and transmitted by C2, C3,... and these data are deciphered by D2, D3,... on the receiving side.;COPYRIGHT: (C)2003,JPO