摘要
提出了一种基于光学柱面衍射的非对称双图像加密方法.首先对两幅灰度图像作离散余弦变换,得到相应的频谱,分别保留两幅离散余弦变换频谱的低频数据和任意1/3的高频数据,并将其中一幅图的低频和任意1/3的高频融合为新的复合频谱,对其进行柱面衍射后进行相位截断生成振幅和密钥.生成的振幅与第二幅图像的低频数据进行相同的加密过程产生新的振幅与密钥.最后将新生成的振幅与第二幅图的任意1/3的高频数据融合为新的复合频谱,通过柱面衍射后的相位截断生成密文和新的密钥,其中密文变成了原图的1/4.对两幅512×512的灰度图像进行加密测试,结果表明重建图像的质量高,相关系数值均高于0.97,峰值信噪比均大于33dB.基于柱面衍射的光学图像加密克服了传统平面衍射的对称性,同时柱面衍射的内柱面半径、柱面高度、衍射距离可以作为加密系统的附加密钥,扩大了密钥空间,增加了系统的安全性.
An asymmetric dual images encryption method based on optical cylindrical diffraction is proposed.Firstly,discrete cosine transform is performed on two grayscale images to obtain the corresponding spectrum.The low frequency data and the 1/3 high frequency data of the two discrete cosine transform spectra are respectively reserved,and the low frequency and the 1/3 high frequency of one of the images are merged into a new composite spectrum,which is subjected to cylindrical diffraction and phase truncation to generate amplitude and a key for decryption.The generated amplitude is encrypted in the same way with the low-frequency data of the second image to generate a new amplitude and a key for decryption.Finally the newly generated amplitude is fused with the 1/3 high-frequency data of the second image into a new composite spectrum.The phase truncation after cylindrical diffraction produces ciphertext and a new key for decryption,where the ciphertext becomes 1/4 of the original image.Numerical simulations prove that the proposed algorithm can effectively perform dual image encryption with high key sensitivity and good robustness.Encryption tests on two images with grayscale of 512×512 show that the reconstructed images are of high quality,the correlation coefficient values are higher than 0.97,and the peak signal-to-noise ratio is greater than 33 dB.The optical image encryption based on cylindrical diffraction overcomes the symmetry of the traditional plane diffraction,and the inner cylinder radius,cylinder height and diffraction distance of the cylindrical diffraction can be used as an additional key to the encryption system,which enlarges the key space and increases system security.
作者
曾健清
王君
吴超
ZENG Jian-qing;WANG Jun;WU Chao(School of Electronics and Information Engineering,Sichuan University,Chengdu,610065,China)
出处
《光子学报》
EI
CAS
CSCD
北大核心
2019年第6期163-172,共10页
Acta Photonica Sinica
基金
四川省科技计划(No.2018GZ0533)~~
关键词
信息光学
双图像加密
离散余弦变换
柱面衍射
相位截断
Information optics
Dual images encryption
Discrete cosine transform
Cylindrical diffraction
Phase truncation
