结合随机数和哈希函数的可重构软件水印方案

提出一种利用哈希函数和随机数特性并结合PPCT和排列图的混合软件水印方案. 利用随机数和哈希函数进行预处理隐藏真实的版权信息，通过修改PPCT的叶节点的左、右指针来创建排列图.在发生版权纠纷时，PPCT或排列图任何一个被提取即可证明版权.利用排列图或随机数可重构嵌入程序中的水印拓扑图,而且，即使在水印被攻击而部分提取的情况下，根据重构的PPCT与提取的PPCT的相似度为证明版权提供证据，进一步增强软件水印的鲁棒性.仿真实验的提取结果表明，混合软件水印方案在删除、修改、增加指针后仍能证明版权，明显增强水印的抗攻击性能.

RECONFIGURABLE MIXED SOFTWARE WATERMARKING SCHEME UTILIZING RANDOM NUMBER AND HASH FUNCTION

It is difficult to protect software copyrights. In order to improve the robustness of software watermarking, a new software watermarking algorithm is proposed combining the advantages of Pareto Diagram, Planted Plane Cubic Tree (PPCT), Hash function and random number. Hash function and random number are used in preprocessing to hide the real copyrights information. The Pareto Diagram is created by modifying the left and right points of the leaf nodes of the PPCT. Both the PPCT and Pareto Diagram can be used to prove the copyright when it is in a copyright disputes. Even when the code pointers have been attacked, this algorithm will make use of the Pareto Diagram or the random number to reconstruct the PPCT of the watermark information which is embedded in programs. Even in the case of partial extraction，it also can provide evidence for the proof of copyright according to the similarity of reconstructing and extracting PPCT and in this way it further enhances the robustness of the software watermarking. The experimental results show that the proposed system can prove the privacy when some points in software watermark have been deleted, modified, or added and it significantly improves the performance against attack.