ABSTRACT In this paper, a double image encryption mechanism for iris template protection using 3D Lorenz chaotic system with modified equal modulus decomposition in the hybrid transform domain is proposed. The hybrid transform is produced by the combination of Walsh transform, Kekre transform and fractional Fourier transform of various orders. Here the fractional orders of the fractional Fourier transform enlarge the key-space of the proposed scheme and improve robustness against brute-force attack. The proposed scheme is asymmetric and non-linear in nature. To validate and authenticate the proposed cryptosystem, the numerical simulations have been performed on grayscale images. Results demonstrate that the proposed cryptosystem has higher robustness against noise and special attacks.

中文翻译：

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混合变换域中使用3D Lorenz系统和修正等模分解的虹膜模板保护双图像加密方案

摘要 在本文中，提出了一种在混合变换域中使用具有修正等模分解的 3D Lorenz 混沌系统的虹膜模板保护的双重图像加密机制。混合变换是由各种阶数的沃尔什变换、凯克雷变换和分数阶傅里叶变换的组合产生的。这里分数阶傅里叶变换的分数阶扩大了所提出方案的密钥空间并提高了对抗蛮力攻击的鲁棒性。所提出的方案本质上是非对称和非线性的。为了验证和验证所提出的密码系统，对灰度图像进行了数值模拟。结果表明，所提出的密码系统对噪声和特殊攻击具有更高的鲁棒性。