ENCRYPTION COMMUNICATION SYSTEM, KEY CENTER DEVICE, CLIENT DEVICE, ENCRYPTION METHOD, AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide an encryption communication system and the like which can suppress delay in generation processing of a shared key and prevent degradation of security in encryption communication.SOLUTION: A key center device comprises: a shared key generation unit 102 which generates an encryption key in response to request from each client device; and a shared key transmission unit 103 which transmits the generated encryption key to the client device. The client device comprises: an encryption key determination unit 201 which determines whether validity of a stored encryption key has not yet expired; an encryption communication unit 202 which performs encryption communication; a key generation request unit 203 which requests the key center device to generate an encryption key; and a shared key reception unit 204 which receives the generated encryption key. Also, the key center device comprises: a load detection unit 101 which determines whether to have a large processing load for generating an encryption key; and a shift quantity determination unit 104 which generates shift quantity to transmit the shift quantity to the client device when it is determined to have a large processing load.