采用变形分数傅立叶变换的光学图像加密

Optical image encryption using anamorphic fractional fourier transform

针对如何在双随机编码中提高加密图像的保密性能,提出了一种新的光学图像加密方法,采用变形分数傅立叶变换的光学结构来完成对图像的加密和解密。其显著特点是在解密时采用了便于光学实现的非负阶次的分数傅立叶变换,能够使加密系统有6个以上的加密自由度,并能增加加密密钥的数量。仿真结果表明:分数阶作为加密密钥的鲁棒性好,被加密图像的保密性能得到提高。

A novel optical image encryption method and its optical implementation are proposed. The method applies an optical architecture of the anamorphic fractional Fourier transform to encrypting as well as decrypting images. It is the unique property to use nonnegative fractional orders in decryption for the purpose of its optical implementation easily. The new method can provide six or more degrees of freedom in encryption . The amount of encryption keys is two more than that of using normal fractional Fourier transform with the same stages. The numerical simulations show that the decryption image will be recognized difficultly when any individual error of the fractional Fourier orders is over 0.005 and the fractional orders being used as encryption keys are quite robust in blind decryption. Therefore it can effectively improve the security of the encrypted image.