Chaotic video objects encryption based on mixed feedback, multiresolution decomposition and time-variant S-boxes

The increasing popularity of multimedia applications creates an increasing need for secure storage and transmission techniques. Especially wireless communications, which can be easily intercepted, should be protected by eavesdroppers. Towards this direction, several encryption schemes have been proposed in literature, however most of them do not consider regions of interest (video objects). These regions may need better protection, may be the only regions that need protection, or should be accessed separately according to different privileges. For these reasons in this paper a video objects chaotic encryption system is proposed. Initially stereoscopic pairs are analyzed and video objects are automatically extracted using a color segments fusion approach. Next for each video object multiresolution decomposition is performed and the pixels of the lowest resolution level are encrypted using a chaotic cipher module. Finally the encrypted regions are propagated to the higher resolution levels and the encryption process is repeated until the highest level is reached. The system presents robustness against known cryptanalytic attacks, enables layered access of multimedia content and the overall security can be enhanced due to region topology.