A Multilevel Asymmetric Scheme for Digital Fingerprinting

The present paper proposes an asymmetric watermarking scheme suitable for fingerprinting and precision-critical applications. The method is based on linear algebra and is proved to be secure under projection attack. The problem of anonymous fingerprinting is also addressed, by allowing a client to get a watermarked image from a server without revealing her own identity. In particular, we consider the specific scenario where the client is a structured organization being trusted as a whole but involving possibly untrusted members. In such a context, where the watermarked copy can be made available to all members, but only authorized subgroups should be able to remove the watermark and recover a distortion-free image, a multilevel access to the embedding key is provided by applying Birkhoff polynomial interpolation. Extensive simulations demonstrate the robustness of the proposed method against standard image degradation operators.