Abstract:

Data transmission in an open network environment is easily stolen or destroyed, therefore, chaotic systems are often used to encrypt multimedia data in combination with various algorithms. Aiming at the problems of traditional scrambling diffusion structure’s low security and depending on a large number of pseudo-random numbers, an image encryption algorithm based on Henon map and improved lifting wavelet transform was proposed. Firstly, the algorithm generated the key by cyclic shift and S-box processing of the pseudo-random sequence generated by chaotic system. At the same time, the plain image was processed to obtain one-dimensional parity sequences. Secondly, the transformed sequence was predicted and updated to get the low-frequency approximate component and the high-frequency detail component of the image. In this way, the primary encryption was completed. Finally, the two scrambled components were flipped separately and the same operation was performed again to achieve encryption. Computer simulation experiment and performance analysis on gray image show that the image encrypted by this algorithm loses obvious statistical characteristics and can resist statistical attacks, thus effectively improve the security of image encryption.

Key words: Henon mapping, lifting wavelet transform, pseudo-random sequences, image encryption