基于矢量分解及双随机相位编码设计了一种光学图像加密系统。通过矢量分解将原始图像分解为两个相位模板, 其中一个相位模板通过双随机相位编码系统进行加密, 另一个相位模板作为额外的密钥, 参与图像的解密, 通过与解密光束相干叠加恢复出原始图像。数值模拟表明, 所设计加密系统具有较好的加密和解密效果, 以及较强的抗噪声和剪切攻击能力。相较于双随机编码系统, 文中加密系统通过矢量分解增加了一个密钥, 拓展了系统密钥空间, 且矢量分解破坏了加密系统的线性关系, 加密系统能够抵御唯密文攻击、已知明文攻击及选择明文攻击, 具有较高的安全性。

An optical image encryption system is designed based on vector decomposition and double random phase encoding. The original image is decomposed into two phase masks. One of the phase masks is encrypted in double random phase encoding system. The other phase mask, which acts as an additional key in the decryption process, is coherently superposed with the decrypted beam to recover the original image. Simulation indicates that the designed encryption system has good encryption and decryption effects, and strong resistance to noise and occlusion attacks. Compared with double random phase encoding system, the designed encryption system has one more key due to vector decomposition, and the key space is thus enlarged. The linearity of the encryption system is broken by vector decomposition. The encryption is resistant to ciphertext-only attack, known-plaintext attack and chosen-plaintext attack, and has high security.