ENCRYPTION COMMUNICATION METHOD, CONTENT DISTRIBUTION SERVER, TERMINAL EQUIPMENT, ENCRYPTION COMMUNICATION SYSTEM, ENCRYPTION COMMUNICATION PROGRAM, AND RECORDING MEDIUM

PROBLEM TO BE SOLVED: To provide an encryption communication method and an encryption communication system capable of ensuring the communication security even for interception of communication data in the case of encryption communication between a server apparatus and a terminal in a two-way broadcast linked service. SOLUTION: A content distribution server generates (S51) a service encryption key Ksv utilized for encryption communication of service information in matching with update (S50) of a scramble key Ks utilized for scramble processing of program contents, encrypts the service encryption key Ksv together with the scramble key Ks by using a CAS card encryption key Kc of a terminal and transmits the encrypted service encryption key Ksv to the terminal (S52). It is difficult to analogize an effective encryption key by means of interception of communication data by a malicious third party by updating the service encryption key Ksv for a short period so as to ensure the security for the encryption communication. COPYRIGHT: (C)2008,JPO&INPIT