Methods of scrambling and unscrambling a video signal, a system, an encoder, a decoder, a broadcast server, and a data medium for implementing the methods

摘要

The invention relates in particular to a method of scrambling a video signal using an encryption key for controlling access to audiovisual information. The video signal is scrambled by applying a tattooing function to the video signal by using a marking key derived from the encryption key, the tattooing function including a parameter for regulating the amplitude of tattooing so as to enable the visibility of the tattooing in the video signal to be adjusted. The invention also provides a dual unscrambling method, and a system, an encoder, a decoder, a broadcast server, and a data medium for implementing said methods.