Patent ID: 6940977
Filing Date: 2005-09-06
Classification: G11B,H04N

Abstract:
1. A works protecting system comprising an AV data transmitting-receiving device for transmitting contents of works and a transmitting-receiving device on another party for receiving the works, wherein said AV data transmitting-receiving device comprises command input means, command control means, AV data transmitting means, encrypting means, first authenticating means, first input/output means, device ID detecting means, and authentication histories storing means, wherein said transmitting-receiving device on another party comprises second input/output means, AV data receiving means, decrypting means, and second authenticating means, wherein the device ID detecting means is configured for detecting, when the transmitting-receiving device on the another party is connected to a transmission line, a device ID thereof, and wherein said authenticating means performs a device authentication operation for mutually checking that both said devices are devices based on certain rules and the detected device ID of the transmitting-receiving device on the another party, and a key exchange operation for sharing a cryptographic key for simultaneously encrypting and decrypting the works when said transmitting-receiving device on another party with a history that authentication has been previously performed therefor is connected to a transmission line.