双随机相位加密系统的已知明文攻击

运用密码分析学的方法对双随机相位加密系统进行了初步的安全性分析.研究结果表明，该系统属于线性的对称分组密码系统，线性性质为其安全性留下隐患.在已知明文攻击下，攻击者可通过常规的相位恢复算法获得4-f系统输入平面的随机相位函数密钥，继而可轻易推出频谱平面的随机相位函数密钥，从而攻破此密码系统. 关键词： 光学信息安全 双随机相位加密 密码分析学 已知明文攻击

Known-plaintext attack on double phase encoding encryption technique

In the field of optical information security, the most attractive work is the so-called double-random-phase encoding encryption scheme proposed by Javidi. However, the security of this cryptosystem has not been analyzed thoroughly from the point of view of cryptoanalysis. In this article, the weakness of Javidi's optical security system is carefully analyzed with a known-plain text attack. It is shown that the double-random-phase encoding encryption scheme is a linear symmetric block cipher cryptosystem and its linearity opens avenues of attacks. Under the known-plaintext attack, attacker can obtain the phase key(s) in the input plane using the typical phase retrieval algorithms and subsequently deduce the phase key(s) in the Fourier domain easily. In addition, an optical implementation of known-plain text attack is also proposed.