一种混沌图像加密算法的选择明文攻击和改进

发布时间：2018-08-30 14:05

【摘要】：在已有的四维超混沌系统的基础上构造了一个五维超混沌系统,对一种结合超混沌序列和移位密码的数字图像加密算法进行了分析,通过选择明文攻击的方法,成功破解了该算法中用于像素位置置乱以及像素值扩散和混淆的等效密钥,从而能利用破解的等效密钥解密出目标明文。为此对该算法进行了两个方面的改进。一个改进是加密系统中使用了新构造的五维超混沌系统,使得改进算法的密钥空间更大,进一步提高了安全性。另一个改进是设计混沌系统的初始值与明文图像的SHA-256哈希值有关,从而使得密钥流与明文图像相关,达到"一次一密"的效果。密钥空间分析、密钥敏感性分析、统计分析、信息熵分析、差分攻击分析、抗剪切、抗噪声、抗压缩分析等实验结果表明,改进后的图像加密算法比原加密算法更加安全有效。
[Abstract]:Based on the existing four-dimensional hyperchaotic system, a five-dimensional hyperchaotic system is constructed. A digital image encryption algorithm combining hyperchaotic sequence and shift cipher is analyzed, and the method of plaintext attack is selected. The equivalent key which is used for pixel location scrambling and pixel value diffusion and confusion in this algorithm is successfully deciphered, thus the target plaintext can be decrypted by using the deciphered equivalent key. For this reason, the algorithm is improved in two aspects. One improvement is the use of a new five-dimensional hyperchaotic system in the encryption system, which makes the key space of the improved algorithm larger and further improves the security. Another improvement is that the initial value of the chaotic system is related to the SHA-256 hash value of the plaintext image, so that the key stream is related to the plaintext image, and the effect of "one time, one density" is achieved. The experimental results of key space analysis, key sensitivity analysis, statistical analysis, information entropy analysis, differential attack analysis, anti-shear, anti-noise and anti-compression analysis show that the improved image encryption algorithm is more secure and effective than the original encryption algorithm.
【作者单位】：聊城大学计算机学院;
【基金】：国家自然科学基金面上项目(No.61573178)
【分类号】：TP309.7;TP391.41

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