结合离散余弦变换与离散小波变换的无损彩色图像加密算法

Lossless Color Image Encryption Algorithm Combining Discrete Cosine Transform and Discrete Wavelet Transform

为使图像在网络中进行安全传输,结合频域领域的图像加密相关研究,提出一种新的彩色图像加密算法。首先将明文图像划分为三基色分量,执行二维离散余弦变换(DCT)得到DC和AC置乱序列;然后对置乱矩阵执行二维离散小波变换(DWT)得到4个子带矩阵,并对置乱后的子带执行逆二维小波变换得到用于扩散的二进制矩阵;接下来将二维十进制矩阵转化为三维二进制矩阵,并对两个二进制矩阵执行异或运算,将其转化为二维十进制矩阵;最后进行扩散操作得到密文图像。实验结果表明,该算法能有效抵抗明文攻击与非法者攻击。

In order to make the image transmission in the network safely,combined with the research of image encryption in the frequency domain,a new color image encryption algorithm is proposed.Firstly,the plain-text image is divided into three primary color components,and the two-dimensional discrete cosine transform(DCT)is performed to obtain the DC and AC scrambling sequences.Nextly,perform two-dimensional discrete wavelet transform(DWT)on the scrambling matrix to obtain four sub-bands matrices,then the binary matrix for diffusion is obtained by performing inverse two-dimensional wavelet transform on the scrambled sub-bands,convert the two-dimensional decimal matrix into a three-dimensional binary matrix,two binary matrices are converted into two-dimensional decimal matrix after XOR operation,and finally perform a diffusion operation to obtain a cipher-text image.The experimental results show that the designed algorithm can effectively resist plain-text attacks and unlawful attacks.