Design And Implementation Of Audio And Video Encryption System Based On Chaos

With the development of the media technology, issues like copyright and privacy have aroused people’s concerns. The multimedia data encryption is the most fundamental and effective method of multimedia protection. However, up to now among multimedia, the audio and video encryption technologies have not been balanced well between the safety and the efficience. So it is a problem to be solved how to encrypt the audio and video files with high efficiency. Regarding this problem, the paper designes an audio and video encryption system based on secure and efficient chaotic encryption technologies, which could encrypt the audio and the video stream in the media files such as MP4 files.Firstly, the paper uses the extended Standard mapping system to generate pseudorandom sequences as encryption keys, and the scale factors in AAC audio frequency are replaced and encrypted with scrambling. The security analysis shows that this algorithm can not only ensure the safety but also improve the efficiency. And the algorithm has no negative influence upon the data volume and the compatibility of the audio stream.Secondly, a spatiotemporal chaotic key generating system using Arnold cat mapping as random coupling is proposed, and a modified Logistic mapping is used as local chaotic mapping. In the meantime, a discretization method which chooses bits randomly to generate pseudo random sequences is proposed. Based on the analysis of H.264 video stream, the intra prediction mode, the motion vector and non-zero luminance coefficients are encrypted with keys generated by the proposed spatiotemporal chaos cryptography. The security analysis shows that this encryption algorithm has a high security level and ensures high efficiency and compatibility under the condition that the data volume of the video stream remains unchanged.Finally, on the basis of audio and video encryption, an encryption system based on chaos is realized. The main functions of this audio and video encryption system are analyzing and playing the AAC audio stream and H.264 video stream in MP4 file, demuxing MP4 file, encrypting the demuxed AAC audio stream and H.264 video stream. This system provides secure and efficient function of audio and video encryption for users with good practicability and maneuverability.