采用超混沌系统的图像压缩加密联合算法

Joint image compression and encryption algorithm using hyper-chaotic system

为了同步实现图像压缩和加密,提出了一种采用超混沌Chen系统和改进零树编码相结合的图像压缩加密算法。该算法在改进零树编码基础上,先利用超混沌Chen系统产生的密钥流修正位平面编码过程中形成的上下文和判决,然后送入MQ算术编码器中进行熵编码生成相应的压缩码流,最后将压缩后码流反馈到超混沌Chen系统的输入端,产生新的密钥,使密钥流和明文相关,实现图像的联合压缩加密。实验结果表明,该算法的峰值信噪比(PSNR)至少提高了1dB,密钥空间为256bit,加密时间占总时间的百分比均小于45%,明文和密钥敏感性高。该算法实现了图像的联合压缩加密,比原始嵌入式零树小波(EZW)算法的图像重建质量高,具有高抗线性攻击和差分攻击能力,密钥空间大,安全性好。

To compress and encrypt images synchronously, a joint compression-encryption algorithm by using a hyper-chaos Chen system and a improved zero tree coding was proposed. Based on the improved zero-tree coding, a key stream produced by the hyper-chaotic Chen system was used to modify the context and the decision after bit-plane encoding, then they were fed into a MQ arithmetic coder to compress and produce the corresponding code streams. The code streams were feedbacked into the input end of hyper-chaos Chen system to produce a new secret key related to the plaintext and to realize the joint compression-encryption. Experimental results indicate that the Peak Signal to Noise （PSNR） of proposed algorithm is improved at least 1 dB, and the key space is 256 bit. The encryption time percentages of total time are all less than 45~//00 and the plaintext and secret have higher sensitivity. The proposed algorithm realizes the synchronization of image compression and encryption, and the image reconstruction quality is higher than that of embedded zero wavelet. It is characterized by the high resistance for linear attack and differential attack, a large key space and better safety performance.