基于非对称密码系统的多图像加密算法

Multiple-image encryption algorithm based on asymmetric cryptosystem

基于变形分数傅里叶变换提出一种非对称光学图像加密算法。在光学系统中,引入非线性相位截断策略消除了线性对称密码系统存在的安全隐患。幅相调制技术结合相位截断运算实现单通道多图像加密,通过重复使用一组光电混合设备,5幅图像被加密为一个实值密文。相位保留运算产生与原始图像相关的4个私钥,变形分数傅里叶变换的分数阶次和4个私钥增大了算法的安全性。数字模拟结果验证了该算法的可行性和有效性,加密和解密图像的均方误差分析了所有密钥的安全性。

A new asymmetric optical image encryption algorithm based on anamorphic fractional Fourier transform （AFrFT） is proposed, which introduces the nonlinear phase-truncated strategy to get rid of the potential insecurity existing in the linear symmetric cryptosystem. The amplitude-phase encoding is employed to achieve single-channel multiple images encryption combining with the phase truncation operation, and five images are encrypted into one real-valued ciphertext by using a set of optoelectronic hy- brid devices repeatedly. Four private keys are generated by phase reservation operation and determined by the original images, and the fractional orders of the AFrFT and the private keys can enhance the safety strength of the encryption algorithm. Numerical simulation results demonstrate the feasibility and effectiveness of the proposed method, and the security of all keys has been analyzed with the mean square error （MSE） between decrypted image and original image.