AUTHENTICATION METHOD, COMMUNICATION SYSTEM, AND REPEATER

摘要

PROBLEM TO BE SOLVED: To provide a communication system where sufficiently high security is ensured for communication. SOLUTION: The system has a gateway server GWS that counts an accurate present time, a mobile phone MS making communication via the gateway server GWS and an IP server W. In the case of an SSL communication with the IP server W, the mobile phone MS acquires time information on the basis of the accurate current time from the gateway server GWS, sets the time on the basis of the time information as the current time of its own phone, uses a public key of an authentication station C to decode a public key certificate (electronic certificate issued by an impartial authentication station C with respect to the public key of the IP server W) sent from the IP server W of the communication opposite party and checks the validity of the public key certificate by using the current time of its own phone (time in compliance with the accurate time in the gateway server GWS).