Patent ID: 8510844
Filing Date: 2013-08-13
Classification: G06F,G11B,H04L,H04N

Abstract:
1. An authorized content verification method in a content transmission and reception system in which a transmitter on a network attaches update information to encrypted content, the update information required to create a content key used for content encryption and decryption, the verification method comprising: transmitting by the transmitter the update information with the encrypted content, in response to a content request from a receiver authorized by the transmitter to decrypt the encrypted content, the update information being changed by the transmitter at a predetermined timing after transmitting the update information to the authorized receiver; transmitting, from the authorized receiver to the transmitter, an authorization verification request including the update information received from the transmitter, a number which varies with each transmission of the authorization verification request, and an identification message created using i) an exchange key shared in advance between the transmitter and the authorized receiver, and ii) the update information transmitted from the transmitter; checking, by the transmitter whether i) the update information included in the authorization verification request received from the authorized receiver satisfies a predetermined condition with respect to the update information currently being used by the transmitter and ii) a part of a hash value which is calculated based on the update information included in the authorization verification request received from the authorized receiver, the number included in the authorization verification request received from the authorized receiver, and the exchange key matches the identification message included in the authorization verification request received from the authorized receiver, the update information being changed by the transmitter in accordance with elapsing of time; creating, by the transmitter, determining, by the authorized receiver, that: