图像加密是信息安全领域的重要内容之一.为此，提出一种基于四元数旋转理论的彩色图像加密方案，并给出了四元数旋转的详细定义及图解，把彩色图像的3个颜色分量作为一个整体进行加密，以实现同步处理.首先将原始图像分解成两个相同尺寸的子图像，并转化成纯四元数矩阵；然后运用四元数的旋转变换性质由给定初始密钥迭代产生大量加密时所需要的密钥，并通过迭代循环的结构体系实现加密.实验结果表明，该方案能够获得较好的彩色图像加密效果，具有较强的安全性以及较快的加解密速度.
Image encryption plays one of the important roles in the field of information security. A new encryption scheme for color image based on quaternion rotation theory is proposed. The detailed definition and diagram of quaternion rotation are also given. The encryption scheme succeeds in getting the three color components of color image as a whole, and treating the encryption operation simultaneously. Original image is firstly decomposed into two of the same size of sub images, and then converted into pure quaternion representation of matrix. By using the property named quaternion rotation transformation, we can obtain a large amount of secret keys from iterations of the given initial secret key. Finally through an iterative loop system, the encryption is realized. The experimental results show that the encryption scheme can achieve great effect, strong security, and faster encryption and decryption speed.
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