Fast self-synchronous content scrambling by spatially shuffling codewords of compressed bitstreams

This paper presents a content access control method by spatially shuffling codewords of the compressed bitstream. This approach is lightweight and incurs no bit overhead. One important advantage of the approach is that the resulting scrambled bitstream can be made compliant to the compression format, thus providing some level of scalability, error resiliency, network friendliness and capability of performing signal processing directly on the encrypted bitstream. In addition, we propose a method for generating or updating the shuffling tables on the fly, based on encrypting some local-content-specific bits using a standard cipher. This local-content-specific bits based table generation process is self-synchronous, which is critical in the presence of packet loss. It also enhances the resistance of this spatial shuffling approach to plain-text attack.