基于均匀置乱和混沌映射的医学图像加密方法

医学图像由于涉及隐私等重要问题，存储与传输过程中需要加密，为了提高医学图像加密的质量并保证加密速度，针对分块后的图像使用一种基于Arnold映射的均匀置乱方法，结合logistic映射生成伪随机数来控制置乱参数，同时对像素点的值进行异或操作以进一步加密图像.实验发现此方法对密钥的敏感性较强，能很好地掩盖图片信息，与单一的logistic映射等加密方法相比，可同时抵御一些裁剪和篡改攻击.上述方法的操作步骤比经典加密算法简单，因此也能满足加密速度的要求.

Medical Image Encrypting Method Based on Even Scrambling and Chaotic Mapping

Medical image involves privacy and other important information， so encrypting medical images during the storage and transmission is essential. In order to improve the quality of the encryption at a high speed， a segmented medical image was treated using an even scrambling method based on the Arnold mapping combined with logistic mapping for generating quasi random numbers to control scrambling parameters. The image was further encrypted through NOR/OR operation of the pixel values. Experimental results show that the method is sensitive to the key and covers the information of an image well， and that it resists cropping and tampering attacks simultaneously， compared with the single logistic mapping method. The operations of the method proposed are simpler than that of conventional ones， so， the method meets the requirement of the encryption speed.