基于一个新的四维离散混沌映射的图像加密新算法

摘要

基于修正版Marotto定理构造了一个四维离散混沌映射,并利用该四维离散混沌映射序列设计了一种图像加密方案.该方案利用图像的256位哈希值来生成混沌序列的初始值,由此混沌序列产生的密钥与明文相关,进一步增强了加密系统的安全性.理论分析和仿真试验表明:该加密方案至少具有3.4×10100的密钥空间;加密后图像直方图接近均匀分布;像素的相关性被消除;信息熵接近8bit,没有明显的统计信息.该加密方案对混沌系统的初始条件扰动极为敏感,任何大于10-15的扰动都将使解密失效;加密图像对明文图像极为敏感,能够抵抗差分攻击.%A novel four-dimensional discrete-time chaotic system was constructed on the basis of a modified version of Marotto's theorem.On the basis of this system,a digital image encryption scheme was proposed,in which the 256-bit hash value of plain image is used to generate the initial value of the chaotic sequence.Therefore,the encryption key generated by the chaotic sequence is related with plain image to enhance the security of the encryption system.Theoretical analysis and simulation experiments show that the key space of the image encryption scheme is as large as 3.4× 10100.The histogram of the encrypted image is dose to the uniform distribution.The correlation of pixels is eliminated.The information entropy of encrypted image is close to 8 bit and the encrypted image has no obvious statistical information.The scheme is extremely sensitive to perturbations of the initial conditions of the chaos system.Any perturbations which are larger than 10-15 will make corresponding decryptions impossible.The encrypted image is also very sensitive to the plain image and can resist differential attack.