关键词: 六维超超混沌, 图像加密, 置乱-扩散, 密钥动态选择机制, 选择明文的攻击

Abstract: In this paper, a six dimensional discrete chaotic system is constructed, and a pseudorandom number generator is designed based on the six dimensional discrete chaotic system. Based on the pseudorandom number generator, an image encryption scheme with key dynamic selection mechanism is proposed. The encryption scheme adopts the classic scrambling-diffusion encryption structure. In this encryption scheme, the scrambling sequence is related to the sum of the pixels of the plaintext image, The diffusion key stream in the diffusion stage is dynamically changing according to the pixel value, so the algorithm can resist the attack of chosen plaintext. In decryption, the decryption key is only the initial value of the chaotic system, and the sum of the pixels of the plaintext image is not needed, In this way, the difficulty of key management in “one time pad” encryption scheme（encryption of different images with different keys） is overcome. The experimental results and security analysis show that the algorithm has the advantages of large key space, no obvious statistical characteristics of ciphertext, sensitive to plaintext and key, and able to resist differential attacks and chosen plaintext attack. It has good application prospects.

Key words: six dimensional hyperchaos, image encryption, scrambling-diffusion, key dynamic selection mechanism, chosen plaintext attack