SESSION CONTROL SERVER, COMMUNICATION DEVICE, COMMUNICATION SYSTEM AND COMMUNICATION METHOD, AND PROGRAM AND RECORDING MEDIUM FOR THE SAME

摘要

A communication device, connected via a network so as to be able to communicate with a session control server, and which establishes a session with another communication device by performing signal transmission to and reception from the session control server, includes: a unit which generates an asymmetric key pair; a request unit which requests certificate issuance for a public key in the asymmetric key pair; a receiving unit which receives notification of public key issuance completion from the session control server; a storage unit which stores a public key certificate which has been received; a sending unit which sends a location registration request of a communication device to the session control server; and a receiving unit which receives a location registration completed notification which includes a term of validity from the session control server; and which sends a location registration request and a certificate issuance request as a combined request.