基于LDPC码和Rao-Nam体制的图像加密方法

An image encryption algorithm based on LDPC and Rao-Nam scheme

为实现图像的纠错码加密,解决图像传输中安全和可靠性问题,提出一种基于LDPC码的Rao-Nam体制的图像加密方法。首先,将图像进行位平面分解;其次,利用混沌系统生成置换矩阵S、P和错误图样E,并与LDPC码生成矩阵G作为私钥;最后对Rao-Nam私钥加密体制进行修正,并用其对位平面矩阵加密得到密文图像。通过实验仿真测试,表明该方法对明文和密钥敏感性强,密钥空间大,具有良好的加密效果和较强的抗信道噪声能力,且对受损密文能较好恢复。

To achieve the image encryption with error-correcting codes and solve the security and reliability of image transmission, the Low-Density Parity Check （LDPC） coding and Rao-Nam private-key cryptosystem were studied. An image encryption algorithm based on Rao-Nam scheme and LDPC coding was proposed. Firstly, the image was divided into 8 bit-planes. Second- ly, the transform matrix S, P and error patterns E was generated by using the chaos system, and the LDPC generator matrix G was designed to act as private-key. Finally, the bit-planes were en- crypted by Rao-Nam private-key cryptosystem and acted as ciphertext image. Experimental re- sults showed that this algorithm had stronger sensitive to the keys and plaintext, and bigger key space. This algorithm showed not only favorable encryption effects and strong ability of resisting channel noise, but also well recovery of impaired encryption image.