Abstract: A medical image encryption is proposed based on the Fisher-Yates scrambling, filter diffusion and S-box substitution. First, chaotic sequence associated with the plaintext is generated by logistic-sine-cosine system, which is used for the scrambling, substitution and diffusion processes. The three-dimensional Fisher-Yates scrambling, S-box substitution and diffusion are employed for the first round of encryption. The chaotic sequence is adopted for secondary encryption to scramble the ciphertext obtained in the first round. Then, three-dimensional filter is applied to diffusion for further useful information hiding. The key to the algorithm is generated by the combination of hash value of plaintext image and the input parameters. It improves resisting ability of plaintext attacks. The security analysis shows that the algorithm is effective and efficient. It can resist common attacks. In addition, the good diffusion effect shows that the scheme can solve the differential attacks encountered in the transmission of medical images and has positive implications for future research.

Key words: medical image encryption, Fisher-Yates scrambling, three-dimensional filter diffusion, bidirectional diffusion, S-box substitution

摘要： 本文提出了一种基于Fisher-Yates置乱、滤波器扩散和S盒替换的医学图像加密方案。首先，通过logistic-sine-cosine系统生成与明文相关的混沌序列，该序列用于算法的置乱、替换和扩散过程。采用提出的三维Fisher-Yates置乱、S盒替换和扩散实现第一轮加密。第二轮加密利用混沌序列对第一轮得到的密文进行置乱，然后利用三维滤波器进行扩散，进一步隐藏有用信息。算法结合输入参数和明文图像的哈希值生成密钥，提高了抗明文攻击的能力。安全分析表明，该算法的性能良好,并且能够抵抗常见的攻击。此外，扩散效果良好，表明该方案能解决医学图像传输中遇到的差分攻击,对未来的研究具有积极意义。

关键词: 医学图像加密，Fisher-Yates置乱，三维滤波器扩散，S盒替换，双向扩散