A method (40, 50) and apparatus (30) for processing a video signal inserts a unique digital signature into the video signal. Thus, rampant duplication or distribution can be traced back to a particular set-top box or receiver. According to one aspect of the present invention, the unique digital signal is inserted into the vertical blanking interval. An apparatus (30) for processing a video signal includes a processor (31) receiving the video signal and outputting a modified video signal having a vertical blanking interval, which includes a digital signature uniquely identifying the processor (31). A memory (33) stores the digital signature and a teletext generator (32) coupled to the memory (33) and the processor (31) and generates a teletext signal that includes the digital signature for insertion into the vertical blanking interval by the processor (31) prior to the processor (31) outputting the video signal.