Patent ID: 7570763
Filing Date: 2009-08-04
Classification: G06Q,H04L,H04N

Abstract:
1. A method for distributing an encryption key of a digital CATV system based on a public-key encryption algorithm, the method comprising the steps of: a) at a head-end, transmitting a session key to a receiver of the subscriber who requests the charged service in response to the request for the charged service of the digital CATV service; b) at the head-end, encrypting an authorization key (AK) using the session key and transmitting the encrypted AK to the subscriber's receiver; and c) at the head-end, encrypting a Channel Key (CK) using the AK and transmitting the encrypted CK to the subscriber's receiver, wherein the step a) includes the steps of: a1) at the head-end, monitoring an insertion of the Condition Access Module (CAM) to the subscriber's receiver when the subscriber requests a charged service to a Registration Authority (RA) having no Condition Access Module (CAM) terminal, through a telephone or a network; a2) at the head-end, generating a session key message to be transmitted to the subscriber's receiver when receiving an alarm message that the Condition Access Module (CAM) is inserted to the subscriber's receiver, and signing a digital signature on the session key message based on digital signature scheme with an appendix; a3) at the head-end, encrypting the digital signed session key message based on a public-key of the subscriber and transmitting the encrypted session key message to the subscriber's receiver; and a4) at the subscriber's receiver, decrypting the encrypted session key message received from the head-end, verifying the digital signature, extracting the session key from the session key message and storing the session key on the Condition Access Module (CAM).