1. A method for verifying an authenticity and integrity of an ordered sequence of digital video frames, the method comprising: providing one or more secret keys; generating digital signatures; and protecting the sequence to produce a protected sequence by embedding in each of at least a portion of the video frames a respective one of said digital signatures according to an embedding pattern, wherein the respective digital signature being dependent on at least one of said one or more secret keys and data of another video frame, wherein generating and embedding the digital signatures is performed during encoding in a single pass.