Abstract: A reprogrammable subscriber terminal of a subscription television service which can have the control program code of its control processor modified by downloading new program code from the headend. The control processor stores a boot program in an internal read only memory. Upon start up and resets, the boot program determines whether the control program should be changed from a command sent from the headend. The command, termed a parameters transactions, includes the number of expected download program code transactions required to complete the control code modification, the memory space areas where the code is to be loaded, and the channel over which the download program code transactions are to be transmitted. The channel is tuned and when the boot program receives all the download program code transactions accurately and stores them, the boot program will cause the control program to be restarted at a selected address of the new or modified control program code which has been downloaded.

Abstract: A method and apparatus for an authenticated electronic userid comprising an adapted digital signature is provided. According to an aspect of the present invention, the adapted digital signature is generated using a secure hash function and an adaptation algorithm. According to one embodiment, a method for creating an adapted digital signature comprises retrieving an originator key, said originator key corresponding to a local userid; running a digital signature engine to create a digital signature, said digital signature based on at least said originator key and remote user information; retrieving a word from a word list, said word corresponding to at least a portion of said digital signature; and returning at least said word as said adapted digital signature.

Abstract: Method and apparatus for modifying or reducing effects of signals added to a video signal to permit more unhampered copying and/or viewing thereof. In one version the method and apparatus replace or level shift portions of a video signal to overcome effects caused by these pulses. Typically these pulses are added for copy protection purposes. Modification of the video signal allows for more unhampered viewing and/or copying of the video signal.

Abstract: Copy protection for composite video signals is well known. Copy protection, while it does not prohibit making a copy per se, does render any copy (recording) of the video signal relatively unviewable so that the viewer's enjoyment of the picture is severely reduced or none. Methods for reducing the effects and/or defeating copy protection are also known. The present method and apparatus reduce effects of added copy protection pulses by further adding other pulses that counteract the gain reduction caused by the copy protection pulses of the type known as automatic gain control (AGC) or pseudo-sync pulses.

Abstract: A watermarking scheme which allows the watermarked image to be authenticated by an authentication agent without revealing the human-readable content of the image. There is disclosed an approach which combines privacy control with watermarking and authentication mechanisms. The watermark can be made to be imperceptible to humans. Public key cryptography allows the authentication agent to authenticate without being able to watermark an image.