Chaos-based Digital Image And Video Encryption Algorithm

Due to the unpredictability and pseudo-random, chaotic sequences are very suitable for encryption. In this paper, theory analysis and numerical experiment are combined to study the encryption algorithm of digital image and video.By analyzing and comparing of several typical chaotic stream cipher and block cipher, the feasibility and advantages of chaotic encryption on images and video are concluded. After analyzing the performances of chaotic sequence, an improved measure for chaotic cipher is proposed.Based on One-way Coupled Map Lattice (OCML) and Tangent Delay Ellipse Reflecting Cavity (TD-ERCS) chaotic system, a new image encryption algorithm is presented. It employs the pseudo-random sequences generated by TD-ERCS as the initial conditions and coupled coefficients of OCML, and the permutation and gray value diffusion eliminate the period phenomenon produced by normal chaos iteration. The new algorithm has features such as simple design and good security.A new chaos-based MPEG video encryption algorithm is put forward. Produced by discrete cat map and piecewise linear chaotic map the chaotic stream cipher is used to encrypt the fixed length data of compressed video. Macro-block scrambling of each frame is conducted through the rearrangement of the chaotic sequence generated by discrete cat map. Base on the open source codec xvidcore-1.1.2, the experiment results show that this encryption algorithm has some merits, such as fast encryption speed, strict size preservation and high security.According to the features of H.264, a chaotic stream cipher based on TD-ERCS is designed to encrypt videos. After properly distributing keys and setting iteration times, the partial key data of video are encrypted. The test results on JM show this new approach is with high security, good real-time and no impact on the video compression.