密钥动态选择机制的图像加密算法

New Image Encryption Algorithm Based on Key Dynamic Selection Mechanism

构造了一个六维离散混沌系统,并在此混沌系统的基础上设计了一个伪随机数生成器。基于该伪随机数生成器提出了一种密钥动态选择机制的图像加密方案。该加密方案采用了经典的置乱-扩散加密结构。在该加密方案中,置乱序列与明文图像的像素总和相关,而在扩散阶段的扩散密钥流是根据每个像素值动态变化的,因此算法能抵抗选择明文(密文)的攻击。解密时的密钥只是混沌系统的初始值,明文图像的像素的总和是不需要的,因此克服了"一次一密"加密方案(加密不同明文所用密钥不同)中密钥管理的难度。实验结果和安全性分析表明:该算法具有密钥空间大、密文没有明显的统计特性、密文对明文和密钥非常敏感、能够抵抗差分攻击和选择明(密)文的攻击等优点,具有良好应用前景。

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.