S盒变换规则融合雅克比椭圆混沌映射的图像加密算法研究

由于当前的基于混沌映射的图像加密算法存在瞬态效应,且在像素扩散阶段都没有使用完整的随机密码序列,从而降低了加密系统的安全性,无法抵御各类明文与密文攻击。对此,设计了一个完整的随机密码序列和新的雅克比椭圆映射,并定义了一个S盒变换规则;构造了预混淆-混淆-扩散结构,提出了S盒变换规则耦合雅克比椭圆混沌映射的图像加密算法。首先利用S盒变换规则对初始图像进行预混淆;再根据Logistic混沌映射与代数变换模型所生成的外部密钥迭代雅克比椭圆混沌映射,以消除瞬态效应;改变初始外部密钥,再次迭代雅克比椭圆混沌映射,用序列修正函数对迭代得到的伪随机序列进行修正,产生的新序列在混淆机制下改变预混淆图像像素值;根据密钥流机制和新序列来设计一个完整的随机密码序列,对混淆像素进行扩散。在MATLAB仿真平台上测试结果表明:该算法高度安全,拥有很强的密钥敏感性,密钥空间巨大。

The Study on Image Encryption Algorithm Based on the S-box Transformation Rule Integration with Jacobian Elliptic Chaotic Map

Because of the current image encryption algorithm based on the chaotic system exist the negative factor induced by the transient effect, and the pixel diffusion phase of theses algorithm was not using the whole random code sequence, resulting in the low security and not against each plain- and cipher- text attack. So the whole random code sequence and new Jacobian elliptic map were designed in this paper, as well as defining a S-box transformation rule; and constructing the pre-confusion-mixing-diffusion architecture, the image encryption algorithm based on the S-box transformation rule integration with Jacobian elliptic chaotic map was proposed to overcome above defects. Firstly, the S-box transformation rule was used to substitute and permute the pixel of original image; secondly, the external key was generated by the logistic map and algebra transformation function to iterate the Jacobian elliptic chaotic map to eliminate the transient effect, and ignore the results of the iteration; changing the external key, one group of pseudo-random sequence was got by iterating the Jacobian elliptic chaotic map again, and the new sequence was obtained by sequence correction function correcting the pseudo-random sequence to mixing the pixel of pre-confusion image under the condition of mixing mechanism; then the key stream mechanism was used to quantify the correcting sequence to obtain the one-dimension array to encrypt the pixel of mixing image under the condition of diffusion mechanism. This algorithm in paper was test on the platform of MATLAB simulation software; the results showed that the image encryption algorithm has a excellent encryption property such as highly secure, strong key sensitivity, the huge key space to against various kinds of attacks.