Rajput Sudheesh K, Nishchal Naveen K
Department of Physics, Indian Institute of Technology Patna, Patliputra, Patna-800 013, India.
Appl Opt. 2012 Aug 1;51(22):5377-86. doi: 10.1364/AO.51.005377.
A single channel asymmetric color image encryption scheme is proposed that uses an amplitude- and phase- truncation approach with interference of polarized wavefronts. Instead of commonly used random phase masks, wavelength-dependent structured phase masks (SPM) are used in the fractional Fourier transform domain for image encoding. The primary color components bonded with different SPMs are combined into one grayscale image using convolution. We then apply the amplitude and phase truncation to the fractional spectrum, which helps generate unique decryption keys. The encrypted image bonded with a different SPM is then encoded into a polarization selective diffractive optical element. The proposed scheme alleviates the alignment problem of interference and does not need iterative encoding and offers multiple levels of security. The effect of a special attack to the proposed asymmetric cryptosystem has been studied. To measure the effectiveness of the proposed method, we calculated the mean square error between the original and the decrypted images. The computer simulation results support the proposed idea.
提出了一种单通道非对称彩色图像加密方案，该方案采用幅度和相位截断方法以及偏振波前干涉。在分数傅里叶变换域中，使用与波长相关的结构化相位掩模（SPM）进行图像编码，而不是常用的随机相位掩模。通过卷积将与不同SPM结合的原色分量组合成一幅灰度图像。然后对分数频谱进行幅度和相位截断，这有助于生成唯一的解密密钥。将与不同SPM结合的加密图像编码到偏振选择衍射光学元件中。该方案缓解了干涉的对准问题，无需迭代编码，并提供了多层次的安全性。研究了针对所提出的非对称密码系统的特殊攻击的效果。为了衡量所提方法的有效性，我们计算了原始图像和解密图像之间的均方误差。计算机仿真结果支持了所提的想法。
