中文摘要：

提出把双随机相位编码中的相位密钥记录为数字全息图，以实现密钥的复制。这能使用户远程访问密文时，可以通过相应的相移算法从记录的数字全息图中重构出相位密钥，并解密得到原始图像。给出了一种可能的应用方案，并分析了CCD噪声对相位密钥重构质量的影响。

英文摘要：

A phase-key duplication technique is introduced. The phase-key in the doudle random-phase encoding system is recorded as digital holograms for this purpose. Therefore,the user who remotely access the encrypted data can recover the original image with the phase-key reconstructed by use of a corresponding phase-shifting algorithm from the recorded holograms. We analyze the influence of the noise in the COD camera on the recording process to the reconstruction of the phase-key. In addition,we also present a possible application of the technique of phase-key duplication based on digital holography.