Patent ID: 7089422
Filing Date: 2006-08-08
Classification: G06T,H04N

Abstract:
1. A method of controlling copying of an information signal in a system having a source of the information signal and a device for copying the information signal, the method comprising the steps of: at an information signal modification source, prior to transmission of the information signal to the copying device, generating a copy control password and a related reference password, and applying to the information signal a substantially imperceptible modification representing copy control data including the copy control password securely encoded according to a predetermined algorithm; delivering the modified information signal from the modification source to the copying device via a communications channel; delivering the reference password from the modification source to the copying device via a separate communications channel independent of the modified information signal; upon reception of the modified signal deriving the copy control data from the modified information signal; comparing the derived securely encoded password with the separately provided reference password securely encoded according to a predetermined algorithm; and enabling copying of the information signal if the securely encoded password derived from the information signal and the securely encoded reference password have a predetermined relationship.