A Quick Glance over the Digital Watermarking

Digital watermarking is a process for modifying physical or electronic media to embed a machine-readable code into the media. The media may be modified such that the embedded code is imperceptible or nearly imperceptible to the user, yet may be detected through an automated detection process. Watermarking is the art of imperceptibly embedding a message into a work. More than 700 years ago in Fabriano (Italy), paper watermarks appeared in handmade paper, in order to identify its provenance, format, and quality. In this context, the watermark is a kind of invisible signature that allows identifying the creator or the owner of a document, and to detect possible copyright violations, and especially non-authorized copying [1]. More recently, different watermarking techniques and strategies have been proposed in order to solve a number of problems, ranging from the detection of content manipulations, to information hiding (steganography), to document usage tracing. In particular, the insertion of multiple watermarks to trace a document during its lifecycle is a very interesting and challenging application [1]. The main property of the proposed method is that it allows the insertion of multiple watermarks by different users, who sequentially come into play one after the other and do not need any extra information besides the public keys. This characteristic makes the present approach more attractive than previously available solutions.