时间延迟与超混沌Chen系统相融合的图像加密算法研究  

The Research of Image Encryption Algorithm Based on Hyper-chaotic Chen System Integration with Time Delay

作　　者：孙力[1] 黄正谦[2] 傅为民[1] 

机构地区：[1]浙江警察学院计算机与信息技术系,杭州310053 [2]浙江大学计算机科学与技术学院,杭州310027

出　　处：《科学技术与工程》2013年第35期10523-10530,共8页Science Technology and Engineering

基　　金：浙江省自然科学基金(LY12F02018)资助

摘　　要：时间延迟是自然界一种普遍存在的现象,在图像加密中的伪随机序列形成过程中同样存在时间延迟现象。超混沌系统由于它具有良好的伪随机性、轨迹难以预测与分析以及相空间极其复杂等特征,使其非常适用于加密领域。但是在当前利用混沌或超混沌系统对图像进行加密的研究中,都没有考虑时间延迟这一特征,使其产生的混沌序列的自相关性不理想,加密效果不佳,无法反映出加密的实际过程。对此,提出一个时间延迟函数与位置索引置乱方法,采用时间延迟与超混沌Chen系统相结合的加密方法来解决此问题。通过时间延迟函数将时间延迟引入到超混沌Chen系统生成的混沌序列中,得到一组关于时间延迟的超混沌伪随机序列;然后利用位置索引置乱方法对其进行置乱,得到一组新的伪随机序列;并利用该序列对图像进行置乱处理;最后采用密钥流机制对时间延迟的混沌伪随机序列进行量化,并利用密钥流机制处理后的新序列对图像进行扩散加密处理。借助MATLAB仿真软件来验证该算法,结果表明:提出的图像加密新算法具有理想的加密性能,所生成的混沌序列的自相关性系数变化更小,其密钥空间相当大,抗攻击能力大幅度提升。Time delay was a widespread phenomenon in nature, the phenomenon of time delay was also existed during the generation of pseudo-random sequence in the image encryption. This system was very suitable for this field due to the characteristics such as the good randomness, difficult to prediction and analyze of the track and complex. However, the phenomenon of time delay was not considered by the researchers when they used the chaotic or hyper-chaotic system to encrypt the image, resulting in the non-ideal autocorrelation of the pseudo-random se- quence and the misadventure performance of encryption. Therefore, a new image encryption algorithm based on the hyper-chaotic Chen system integration with time delay to solve this problem. The time delay was introduced into the chaotic sequence generated by hyper-chaotic Chen system to obtain the hyper-chaotic pseudo-random sequence on the time delay; the permutation method of position index was used to permute the row and column of the pseudo-random sequence on the time delay to get a new group pseudo-random sequence, and used it to permute the image; Finally, the key stream sequence was used to treat the new pseudo-random sequence and the diffusion function to encrypt image. The MATLAB simulation software was used to validate the method proposed, the results show that the image encryption algorithm had better encryption performance, the key space is larger, the anti-plaintext attack property was greatly enhanced, and the variation of autocorrelation of chaotic sequence was smaller.

关 键 词：时间延迟 位置索引置乱 自相关性 密钥流机制 抗攻击 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]