Abstract: Aiming at the problem of low data embedding rate of dynamic watermarking,this paper proposed a dynamic-graph watermarking algorithm based on Petri net coding.First,the watermark information is converted into a sequence,and then it is encoded into a running state sequence of Petri net.Finally,the code that generates the Petri net structure is embedded into the source code of the protected software.Since the Petri net transitions will produce different marks,the multiple values are expressed in the same Petri network structure,which means that the watermarking scheme has high data embedding rate and error detection ability,and can successfully resist multiple and typical attacks such as the insertion of nodes,the deletion of transitions,the deletion of places and the deletion of arcs.Finally,the feasibility and effectiveness of the algorithm were verified in the experiment,and the distortion attack test was carried out.The result shows that the dynamic map software watermark based on Petri net coding is robust,and it has a strong ability to resist distortion.

Key words: Software protection, Software watermarking, Dynamic-graph watermarking, Petri net coding, Data embedding rate