基于振幅调制的菲涅耳域的光学图像加密技术

针对基于菲涅耳域的双随机相位加密系统不能抵抗选择明文攻击的弱点,提出了一种基于振幅调制的菲涅耳域的图像加密方法。该方法通过在系统第二块随机相位板后面添加一个振幅调制密钥来实现加密,同时分析了该密钥的安全性,密钥参数对加密效果的影响。实验表明振幅调制密钥的密钥空间非常大,且正常解密时密钥吻合度要求非常高,攻击者很难获取原始图像的信息;另一方面引入振幅调制密钥后扰乱了系统固有的线性性质,添加非线性环节,从而提高了系统的抗选择明文攻击能力。研究可知:引入振幅调制技术后系统的安全性和抗攻击能力大大提高,加密效果良好。

Optical image encryption technique based on amplitude modulation in the Fresnel domain

Double random phase encoding system in the Fresnel domain has a vulnerability to a chosen-plaintext attack. To overcome this weakness, an image encryption method based on amplitude modulation is proposed. It is implemented by adding a key for amplitude modulation behind the second random phase mask, also the security of the key and the effects of parameter on the performance of the encryption are systematically analyzed. The experiments show that the key space for amplitude modulation is huge, and moreover the key requires a high conformability for normal decryption. It is very difficult for attackers to obtain the information of the original image. Meanwhile, as an additional nonlinear operation, the introduced key can disturb the linearity of the system, thus enhancing the resistance against to a chosen-plaintext attack. Research has proved that the security and resistance against attacks of the system are highly enhanced with amplitude modulation, thus the effect of encryption is well.