Patent ID: 8160157

Claim:
A method of enciphering a data bit stream exchanged between a coder and a decoder in a video system, comprising: selecting, during a coding stage for the data bit stream according to a video standard, in the data bit stream a set of code words to be ciphered according to a predetermined encipherment algorithm and a key; and enciphering at least one code word of the selected set of code words to generate a unique ciphered bit stream, the enciphering comprising: extracting at least a sub word from the at least one code word of the selected set of code words; and substituting the extracted sub word with another sub word according to the predetermined encipherment algorithm and the key, the another sub word being arranged so that the data bit stream after the substitution of the extracted sub word is compatible with the decoder according to the video standard without causing desynchronization, wherein the video standard is H.264 video standard, and the at least one code word of the selected set of code words is an H.264 Intra prediction mode code word.