在光学信息安全领域,双随机相位加密方法最引人注目并得到广泛研究,但由于双随机相位加密系统是基于傅里叶变换的系统,其本质上是一种线性变换系统,明文、密文之间的函数依赖关系比较简单,这就为其安全性留下了很大的隐患。双随机相位加密方法可以用光学和数字的方式实现,提出了一种选择明文攻击的方法,利用多个冲击函数作为选择的明文,成功破解了基于数字方法实现的双随机相位加密系统,并给出了恢复密钥的解析式,此方法最大的优点在于解密图像的无损性,并从理论上加以证明,给出了实验结果。

In the field of optical information security, the most attractive work is the so-called double random phase encoding encryption scheme. This encryption method is based on the principle of Fourier transform algorithm and its linearity opens avenues of attacks. Double random phase encoding encryption can be implemented optically or digitally. We demonstrate a new approach to chosen-plaintext attack on double-phase encoding encryption system implemented digitally. With this attack an opponent can access both random phase keys with the help of impulse functions. The expressions of retrieved keys are also given. One of the most apparent advantage of proposed approach is that the decryption process is lossless. Numerical simulations show a good agreement with theoretical analysis.