Method for transmission/reception of contents usage right information in encrypted form, and device thereof

Abstract

A license-data transmitter (in a case of recording, a recording deviceserves as a license-data transmitter, and in a case of readout, a storage deviceserves as a license-data transmitter) verifies a certificate C[KPdx] (the license-data receiver and the license-data transmitter will be represented by 'x' and 'y', respectively) of a license-data receiver (in a case of recording, a storage deviceserves as a license-data receiver, and in a case of readout, a reproducing deviceserves as a license-data receiver), following which the license-data transmitter transmits a certificate C[KPdy] thereof to the license-data receiver in the form of challenge information E(KPdx, Kcy)//C[KPdy]. Then, the license-data receiver verifies the certificate C[KPdy] of the license-data transmitter. Only in a case that the license-data transmitter device has been authorized, the license-data receiver transmits the session information E(Kcy, E(KPdy, Ksx)//KPpx) to the license-data transmitter in response to the challenge information. The license-data transmitter provides the license data to the license-data receiver using the key Ksx and KPpx thus received.