In a system including a client, a print server, an image forming device and a database, when the print server verifies a certificate transmitted from the image forming device upon performing TLS communication, verification of certificates that are registered in advance with the database is accelerated. A search key, which is for acquiring information of a desired image forming device from data stored in the database, is set in the print server. Certificate information is registered with the database in association with the search key. In this way, the certificate information can be searched for using the search key and verification can be accelerated.