Abstract In this paper, we proposed an iterative attacking algorithm to the pure phase asymmetric optical cryptosystem based on unequal modulus decomposition. Furthermore, we have proposed a secure asymmetric cryptosystem based on cascaded unequal modulus decomposition in the Fresnel domain. Fresnel transform and unequal modulus decomposition are highly sensitive to their parameters. An input grayscale image is first convoluted with a random phase mask, then Fresnel transformed, and followed by unequal modulus decomposition. This process is cascaded twice to get an encrypted image, which is quite random and looks like a noisy white image. The scheme is validated on various types of grayscale and binary images, but simulations are demonstrated for Binary dots, Boat, Jetplane, Medical, and Vegetable images. The results show that the proposed cryptosystem eliminates the silhouette problem and endures statistical and special attacks. The statistical attack based on the histogram, entropy, and correlation distribution analysis on neighbouring pixels is performed on the proposed cryptosystem. Results are shown in terms of statistical metrics such as correlation coefficient and mean squared error between plaintext and ciphertext. The proposed scheme also resists noise attack. The results show that the proposed scheme is highly secure and resist the cryptographic attacks.

中文翻译：

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基于菲涅尔域的密码系统级联不等模分解增强图像安全性

摘要 本文提出了一种基于不等模分解的纯相位非对称光密码系统迭代攻击算法。此外，我们提出了一种基于菲涅耳域级联不等模分解的安全非对称密码系统。菲涅尔变换和不等模量分解对其参数高度敏感。输入的灰度图像首先与随机相位掩模进行卷积，然后进行菲涅耳变换，然后进行不等模分解。这个过程被级联两次以获得加密图像，这是非常随机的，看起来像一个嘈杂的白色图像。该方案在各种类型的灰度和二值图像上进行了验证，但对二值点、船、喷气式飞机、医疗和蔬菜图像进行了模拟。结果表明，所提出的密码系统消除了轮廓问题，并能承受统计和特殊攻击。对所提出的密码系统进行了基于直方图、熵和相邻像素相关分布分析的统计攻击。结果以统计指标显示，例如明文和密文之间的相关系数和均方误差。所提出的方案还可以抵抗噪声攻击。结果表明，所提出的方案具有较高的安全性和抵抗密码攻击的能力。结果以统计指标显示，例如明文和密文之间的相关系数和均方误差。所提出的方案还可以抵抗噪声攻击。结果表明，所提出的方案具有较高的安全性和抵抗密码攻击的能力。结果以统计指标显示，例如明文和密文之间的相关系数和均方误差。所提出的方案还可以抵抗噪声攻击。结果表明，所提出的方案具有较高的安全性和抵抗密码攻击的能力。