基于动态S盒机制及其分块优化的块加密实时更新算法研究

为了确定图像块加密算法中的S盒所能加密的最大分块数量;并能保证每个S盒在整个加密期间都可实时更新,提出了动态S盒和密文反馈机制。引入单一性距离,优化了每个S盒所能加密的最大分块数量。利用不同的S盒加密不同的分块,根据动态S盒机制形成S盒集合,用该集合根据左循环移位置乱图像分块;再用不同的S盒根据替代-移位操作加密置乱分块。设计的密文反馈机制改变混沌映射迭代次数,增强每个S盒与明文图像之间的关系,确保本文算法可实时更新。MATLAB仿真结果表明:动态S盒的非线性很高;且与其他算法相比,算法可实时更新,其安全性最高,密钥空间大,抗攻击能力强。

The Study of Image Block Encryption Update Algorithm Based on Dynamic S-boxes Mechanism and Its blocks Optimization

In order to determine the maximum number of blocks encrypted by the current image blocks encryption algorithm; and guarantee the keys used by the each S-boxes during the diffusion can be real-time update. The dynamic S-boxes mechanism and cipher feedback mechanism were proposed, and introduced the single distance to optimize the maximum number of blocks encrypted by each S-box. The sets of dynamic S-boxes were generated by the generation method of dynamic S-boxes, and the blocks were permutated by the S-boxes set according to the left cyclic shift operation; the permutated blocks were encrypted by different S-boxes according to the substitution and shift operation. The cipher feedback was used to change the iteration times of chaotic map to get a new dynamic S-boxes set for enhance the relations between the plaintext and S-boxes as well as ensuring this algorithm can real time update. Finally the MATLAB simulation platform was used to test this algorithm; the results showed that the S-boxes have a higher linear property; and compared with other algorithms, this algorithm had a highest security, huge key space and strong anti-attack capability.