基于分阶Fourier频谱分解与混合随机掩码的光学加密算法  

Optical Encryption Algorithm Based on Fractional Fourier Spectral Decomposition and Mixed Random Mask

作　　者：潘良 邱建林[2] PAN Liang;QIU Jian-lin(School of Computer and Information Engineering, Nantong University of Technology, Nantong 226002,China;School of Computer Science and Technology, Nantong University, Nantong 226002,China)

机构地区：[1]南通理工学院计算机与信息工程学院,南通226002 [2]南通大学计算机科学与技术学院,南通226002

出　　处：《科学技术与工程》2019年第14期249-256,共8页Science Technology and Engineering

基　　金：国家自然科学基金(61202006);计算机软件新技术国家重点实验室开放课题基金KFKT2012B29);江苏省科技创新基金(BC2013167)资助

摘　　要：为了解决当前光学加密方法主要是借助普通相位掩码来调制初始图像,导致输出密文的安全性不理想的问题,通过融合Fresnel波带、Hilbert相位与混沌掩码,设计了分阶Fourier频谱分解与混合随机掩码的光学图像加密算法。首先,根据SHA-256哈希方法,形成一个256位的外部密钥,并将其分割为32个子密钥;引入二维Ushiki映射,利用子密钥来计算其初始条件,通过迭代来输出一组随机序列,从而构建一个混沌相位掩码;随后,引入Fresnel波带振幅与Hilbert相位函数,将二者与混沌相位掩码融合,形成一个混合掩码,兼顾其随机性与光轴校准精度;基于分阶Fourier变换,联合混合掩码,对初始明文完成光学调制,获取Fourier频谱;最后,通过等模分解方法来分割Fourier频谱,输出密文与私钥。测试数据表明:较已有的光学加密方案而言,所研究加密技术具备更理想的抗干扰能力与安全性,在噪声、剪切等攻击下,具有更为理想的解密质量。In order to solve the defect as low security of output cipher induced by using the ordinary phase mask to modulate the initial image in current optical image encryption methods,the optical image encryption algorithm based on fractional Fourier spectral decomposition and mixed random mask was designed by fusing Fresnel band,Hilbert phase and chaotic mask. Firstly,the 256 bit external key was formed according to the SHA-256 hash method and divided it into 32 sub-keys. The initial conditions of two-dimensional Ushiki map were computed by these subkeys,which was used to iterate the Ushiki map for obtaining a group of random sequences to construct the chaotic phase mask. Then,the Fresnel band amplitude and Hilbert phase function were introduced to fuse the chaotic phase mask for forming a hybrid mask,which took into account the randomness of the mask and the calibration accuracy of the optical axis. The optical modulation of the original plaintext was completed based on fractional Fourier transform and hybrid mask to obtain Fourier spectrum. Finally,the Fourier spectrum was segmented by the equal modulus decomposition method to output the ciphertext and the private key. Test data show that the proposed encryption scheme has better anti-disturbance ability and higher security,which has better quality of decryption under noise,shearing and other attacks compared with current optical encryption scheme.

关 键 词：光学图像加密 二维Ushiki映射 混沌相位掩码 Fresnel波带 Hilbert相位函数 分阶Fourier变换 等模分解 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]