Partial Video Encryption Based on Alternating Transforms

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In this letter, we propose a novel video encryption technique that is used to achieve <emphasis emphasistype="italic">partial</emphasis> encryption where an annoying video can still be reconstructed even without the security key. In contrast to the existing methods where the encryption usually takes place at the entropy-coding stage or the bit-stream level, our proposed scheme embeds the encryption at the <emphasis emphasistype="italic">transform</emphasis> stage during the encoding process. To this end, we develop a number of new unitary transforms that are demonstrated to be equally efficient as the well-known DCT and thus used as alternates to DCT during the encoding process. Partial encryption is achieved through alternately applying these transforms to individual blocks according to a pre-designed secret key. Analysis on the security level of this partial encryption scheme is carried out against various common attacks and some experimental results based on H.264/AVC are presented. </para>