Patent ID: 8223967

Claim:
A semiconductor integrated circuit for use in an audio-video device arranged to produce audio-video signals from received encrypted broadcast signals without requiring receipt of one or more transmitted keys, comprising: an input interface structured to receive an encrypted enable signal; an output interface structured to output audio-video signals; one or more hardware circuit portions each structured to process data in relation to the audio-video signals; a first decryption circuit structured to receive the encrypted enable signal to decrypt the encrypted enable signal in accordance with a key stored on the integrated circuit and to provide a plain text message without requiring receipt of one or more transmitted keys; a memory structured to store a stored value for the circuit; an enabling circuit structured to generate an enable signal or a disable signal to selectively restrict, deny, or allow operation of at least one of the one or more hardware circuit portions; a common key store structured to store a common key; a comparison circuit structured to compare the plain text message with the stored value and to selectively instruct the enabling circuit if the plain text message and the stored value match; and a second decryption circuit structured to receive the common key from the common key store in the integrated circuit and to decrypt the received encrypted broadcast signal in response to receipt of the common key and the generation of the enable signal.