基于级联迭代傅里叶(CIFT)变换算法提出了一种新的光学图像的加密方法，该方法通过输入和4-F相关的傅里叶域的模糊设计和定位，从而实现光学加密以及真实性验证。与以往的方法有所不同，新算法采用改进的搜索策略：修改两个阶段的同步分布，同时扩大搜索空间。计算机模拟实验表明其快速的收敛算法能够更好地恢复图像的质量，密钥会被分配到不同的方面，用户只有在得到这些密钥的授权之后才能得到解密后的图像，这种密钥分配策略可以极大减少被入侵的风险。%A Cascaded Iterative Fourier Transform (CIFT) algorithm is presented for optical security applications. Two phase-masks are designed and located in the input and the Fourier domains of a 4-F correlator respectively,implementing the optical encryption or authen-ticity verification. Compared with previous methods,the proposed algorithm employs an improved searching strategy:modifying the phase-distributions of both masks synchronously as well as enlarging the searching space. Computer simulations show that the algorithm results in much faster convergence and better image quality for the recovered image. Each of these masks is assigned to different person. There-fore,the decrypted image can be obtained only when all these masks are under authorization. This key-assignment strategy may reduce the risk of being intruded.
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