To improve the security and reliability of image transmission, an image encryption algorithm based on combination Low Density Parity Check ( LDPC) coding with chaotic system was proposed. Firstly, the algorithm used parity encoding to extend pixels' value of image into 10 bits and calculated its deviation acted as chaotic initial value. Secondly, Arnold transformation was used to scramble the positions of image pixels and Henon mapping was used to diffuse the values of pixels. Finally, the high 2 bits were separated from 10 bits of pixel value and transmitted faultlessly by LDPC code, the other 8 bits acted as the encryption result. The experimental results show that the proposed algorithm has strong sensitivity to the keys and plaintext, possesses favorable avalanche effect, and it can resist plaintext attack and differential attack effectively. Moreover, the encryption result has strong ability of resisting cutting and noise attacks.%为提高图像传输的安全性和可靠性,提出一种结合LDPC编码和混沌系统的图像加密方法.首先,通过奇偶校验码将像素值扩展为10比特,并计算标准差作为混沌映射初值；其次,使用Arnold变换置乱像素位置,并利用Henon映射扩散像素值；最后,从10比特像素值中分离高2比特经LDPC编码实现无差错传输,而其余8比特则为加密结果.实验结果表明,所提方法对密钥及明文敏感性强,具有良好的雪崩效应,能有效抵抗明文和差分等攻击,同时其加密结果具有较强的抗剪切和抗噪声攻击能力.
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