Separable Robust Reversible Watermarking in Encrypted 2D Vector Graphics

Abstract

To accomplish robust watermark extraction in reversible watermarking both in plaintext domain and encrypted domain, a separable robust reversible watermarking in encrypted 2D vector graphics is proposed in this paper. Firstly, a content owner uses a key to scramble the polar angles of the vertices to encrypt the graphics in the polar coordinate system. Consequently, a watermark embedder maps the encoded watermark segments to different vertices under the control of an embedding key and an HMAC (hash-based message authentication code) function. After that, the polar angle of the vertex is slightly adjusted to embed a watermark. Since the decryption operation does not affect the embedded watermark, the watermark can be extracted both in the plaintext and encrypted domain. Experimental results and analysis show that the proposed scheme can achieve good invisibility and reversibility. It can effectively resist normal operations such as rotation, scaling, translation (RST) and entity reordering, and it has good robustness against malicious attacks such as vertices/entities addition, deletion and modification.