The double random phase encoding techniques have received considerable attention from researchers in recent years because of their advantages of parallel and high-speed processing capability. Meanwhile, the security of the cryptosystem is also one of the major concerns. We experimentally showed the ciphertext redundancy vulnerability of the coherent double random phase encryption (DRPE) system. Based on the statistical ergodicity of speckles and the consistency of the energy spectral density (ESD), we have proved that the method can retrieve the most plaintext information from partial ciphertext alone. We performed the simulation and experimental results to verify whether the algorithm is effective. The ciphertext redundancy of the DRPE system is analyzed from the results of the ciphertext occlusion test. There is a risk of plaintext leakage in this scheme, as long as the average ESD can be estimated from the sub-images. The results will further our understanding of the limitation of current optical security techniques. The DRPE system has potential redundancy risk. This vulnerability allows a cryptanalyst to estimate the plaintext information with only a half or less ciphertext.

双随机相位编码技术由于具有并行和高速处理能力的优点，近年来受到了研究人员的广泛关注。同时，密码系统的安全性也是主要关注点之一。我们通过实验展示了相干双随机相位加密 (DRPE) 系统的密文冗余漏洞。基于散斑的统计遍历性和能谱密度（ESD）的一致性，我们证明了该方法可以仅从部分密文中检索出最明文的信息。我们进行了仿真和实验结果来验证算法是否有效。从密文遮挡测试结果分析DRPE系统的密文冗余度。该方案存在明文泄漏的风险，只要可以从子图像中估计出平均 ESD 即可。结果将进一步我们了解当前光学安全技术的局限性。DRPE 系统存在潜在的冗余风险。该漏洞允许密码分析者仅用一半或更少的密文来估计明文信息。