Methods for encrypting and decrypting MPEG video data efficiently

Mu!timedta data security is very important for rrtultimedia commerce on the Internet such as video-ondemand and rea!-time video mu[ticast. Howeverl traditional cryptographic algor’zthms for data secrecy such as DES are not fast enough to process the vast amount of data generated by the multimedia applications to meet the real-time constraints required by the multimedia applications. How to incorporate cryptographic technology with digital image processing technology to provide multimedia security does not seem to be considered in the previous literatures. The main contribution of this paper is the idea of incorporating cryptographic techniques (random algorithms) wath digata[ amage processing techniques (image compression algorithms) to achieve compression (decompression) and encryption (decryption) in one step. One of our methods is almost as e@cient as the existing video encoding and decoding process while providing considerable level of security without affeciing the quality of images when decrypted. Our methods are also adjustable to provide diflerent levels of security for different requirements of the multimedia applications. Our methods are based on the wideiy used JPEG and MPEG standards. We also conduct a series of experimental studies to test and evaluate our algorithms.