Abstract In this paper, a silhouette-free and crosstalk-free multiple-color-image cryptosystem is presented based on unequal modulus decomposition (UMD) in the gyrator transform (GT) domains. To the best of our knowledge, it is the first time that the use of cascaded GT, UMD, and inverse-GT operations is demonstrated which features four-orders-of-magnitude higher sensitivity relative to the known GT-UMD cryptosystems. This significantly enlarges its key space. It is demonstrated that this method eliminates the silhouette and cross-talk problems which are well-known in previous interference-based and multiple-image cryptosystems. The polarization and time degrees of freedom (DoFs) are harnessed to realize the proposed cryptosystem using a compact optical system. Also for more compactness, the inverse-GT operation is performed by propagating the beam carrying the image in the reverse direction through the optical GT system. The cryptosystem is verified robust against occlusion, noise, statistical attacks, as well as the chosen-plaintext attack. The quality of the output images is found unaffected by the number of encrypted images which offers ultimately high multiplexing capacity.

中文翻译：

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基于多色图像不等模分解的紧凑型光学非对称密码系统

摘要 在本文中，基于回转器变换（GT）域中的不等模分解（UMD），提出了一种无轮廓和无串扰的多色图像密码系统。据我们所知，这是第一次展示级联 GT、UMD 和逆 GT 操作的使用，其具有相对于已知 GT-UMD 密码系统高四个数量级的灵敏度。这显着扩大了其密钥空间。证明该方法消除了先前基于干扰和多图像密码系统中众所周知的轮廓和串扰问题。利用偏振和时间自由度 (DoF) 来使用紧凑型光学系统实现所提出的密码系统。也为了更紧凑，逆 GT 操作是通过光学 GT 系统沿相反方向传播携带图像的光束来执行的。该密码系统经验证可抵抗遮挡、噪声、统计攻击以及选择明文攻击。发现输出图像的质量不受提供最终高复用容量的加密图像数量的影响。