Fractional transform based image encryption methods have been widely studied in recent years. However, most of the existing fractional transform based image encryption methods are defined in the complex field. Thus, the en-crypted images contain both phase and amplitude information, which is not conducive to transmission and storage. Moreover, some encryption methods that meet the requirements of reality-preserving have problems of relatively single keys, lacking of sensitivity and so on. An image encryption method was proposed based on multiple-order fractional dis-crete Tchebichef transform and generating sequence. The proposed method used randomly generated row and column vectors and generating sequence generated by Chaotic sequences as keys to encrypt images, which not only satisfied property of reality-preserving transmission but also greatly expanded the key space. The experimental results further demonstrate that the proposed encryption method can resist a variety of attacks, and decrypted images are almost non-distored, which indicate excellent encryption effect, sufficient security and robustness of the method.%基于分数阶变换的图像加密方法近些年被广泛研究和使用,然而现有的基于分数阶变换的图像加密技术多在复数域进行,加密后的图像既包含了相位信息也包含了振幅信息,不利于传输和存储.另外,一些满足保实性的加密方法,则存在密钥相对单一、敏感性不足等问题.基于此,提出一种基于多阶分数离散切比雪夫变换和产生序列的图像加密方法,该方法使用随机生成的行、列分数阶向量以及通过混沌序列生成的产生序列作为密钥对图像进行加密,在满足实值传输的同时大大扩展了密钥空间.实验结果进一步表明,该加密方法可以抵抗多种攻击,解密后的图像几乎无失真,具有很好的加密效果以及足够的安全性和顽健性.
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