A reversible watermarking for authenticating 2D vector graphics based on bionic spider web

Based on the principle of predation using spider web, a novel semi-blind and semi-fragile reversible watermarking scheme for authenticating 2D vector graphics is proposed. Aiming to resolve the problem of the deficiency in robustness resulting from watermark embedding in file stream order, this scheme proposes to embed geometric correlated watermark by adding vertices for entities. Firstly, two spider webs are generated based on the convex hull of 2D vector graphics and a secret key. Secondly, let the first spider web intersect with the 2D vector graphics, and some vertices are added at the intersections. After that, let the second spider web intersect with the 2D vector graphics, and record the number of intersections between every cobweb and entities. The authentication is carried out by checking the intersection states and the number of intersections between the 2D vector graphics and two spider webs. Experimental results and analysis show that it can localize the tampers in entity with the premise that the convex hull is kept. Meanwhile, the watermarking can keep the shape of 2D vector graphics, and it is robust against translation, scaling, rotation and even entity rearrangement. It provides a novel means for the content protection of 2D vector graphics.