Compressed-domain scrambler/descrambler for digital video

Multimedia data security is very important for multimedia commerce on the Internet and real-time video multicast. However, traditional encryption algorithms for data secrecy, such as DES, may not be suitable for multimedia applications because they are unable to meet the real-time constraints required by the multimedia applications. For multimedia applications, lightweight encryption algorithms are attractive. This paper examines the joint encryption and compression framework in which video data are scrambled in the frequency domain by employing selective bit scrambling, block shuffling and block rotation of the transformed coefficients and motion vectors. In addition a lightweight MPEG video encryption algorithm is proposed whose primary motivation is to save the encryption computation by taking the advantage of combining MPEG compression and data encryption, and at the same time avoids adverse effects on the video compression rate.