Safeguarding the Digital Contents: Digital Watermarking

DESIDOC Journal of Library & Information Technology, Vol. 29, No. 3, May 2009, pp. 29-35 © 2009, DESIDOC Safeguarding the Digital Contents: Digital Watermarking M. Natarajan and Gayas Makhdumi1 NISCAIR, 14, Satsang Vihar Marg, New Delhi-110 067 E-mail: 1 Department of Library & Information Science, Jamia Millia Islamia University, New Delhi-110 025. E-mail: ABSTRACT Digital watermarks are one of the tools which helps to make the distribution of digital material more secure. It is a kind of digital signal or pattern hidden directly in digital content. The paper deals with the multi-faceted aspects of digital watermarking (DWM) technology. It also discusses the need for DWM with the properties like robustness, security, invertibility, transparency, complexity, capacity, and verification. The key aspects are given with the solutions for DWM. Few companies involved in DWM activities are discussed with the technique of embedding with different types of watermarks. It discusses tool and techniques for images, text, and other applications of DWM. The possible attacks on DWM and the organisations involved in developing standards for it are described. It has been concluded that the protection of individual rights is a must, and deeper understanding of the DWM will lead to the design of more reliable systems for safe-guarding digital contents. Keywords: Digital water marking, DWM, safeguarding, digital library, watermarking 1. INTRODUCTION The popularity of World Wide Web demonstrated the commercial potential of offering multimedia resources through the digital networks. Since commercial interests seek to use the digital network to offer digital media for profit, they have a strong interest in protecting their ownership rights. The digital data can be processed, accessed, and it can be transmitted very quickly using networks. There are numerous technical, legal, and organisational problems which arise when there is widescale use of digital documents. Digital information can be copied any number of times from one medium to another; they can be transmitted through networks, etc., all without compromising the quality of the data. There is no way to distinguish between an original electronic documents and its copy. It is easy to change any part of an unprotected electronic document. One possibility here is to replace original signatures with cryptographic methods. Digital signature is data items formed by the signatory and created from the document that is to be signed. It relates the documents to the signatory in a Received on 25 November 2008 secure and reliable way. The signature of one document cannot be used to sign another, even if the two documents in question differ by just a single character. Digital watermarking has been proposed as one way to accomplish this. Also advanced Internet services enabled the users to create copy and distribute multimedia products such as audio, video, and still images with much ease and less effort, minimum or no cost, and in less time. Though it encouraged trading on the Internet, but on the other hand it has created the problem of illegal copying or copyright infringement. E-commerce has become a significant business with well-established online shopping services, and online delivery of digital media such as audio and video. Thus, protection of digital rights assumed a primary importance in the digital age. 2. PROTECTION TECHNIQUES Significant research has been conducted since 1996 on copyright protection and authentication. Steganography, cryptography, digital watermarking, etc., have become the most relevant and significant topics for research scientists and vendor consortiums. Because of the massive illegal copying of media files, content owners 29 utilise various protection technologies like digital rights management (DRM) and/or digital watermarking. DRM is one of the way to protect and secure the rights of the author (owner) on the contents of the product. DRM links specific user rights to media in order to provide persistent governance of user activities such as viewing, accessing, and duplication. The management technique is aimed at balancing information protection, usability and cost to provide beneficial environment for all parties concerned. It is achieved through the interaction of effective and economic models, social values, legal policy, and technology. Copyright protection inserts authentication data such as owner registration, buyer and seller information and logo in the digital media without sacrificing quality. In case of any dispute, the data of authentication is extracted from the product and can be used as an authoritative proof to prove the ownership or copyrights. Copyright infringement includes the user activities beyond the fair use of digital media. DRM is regarded as an extension of copy protection measures1. 3. data or cover could be any multimedia product such as still images, audio data, video clip, or text document. Watermark can be any useful information to prove the authenticity of the owner. The host and watermark are never separated so that the embedding watermark is the key point in this DWM. Once embedded, the watermark is invisible in the host. The original content is called the cover or the host and embedded message is known as watermark and the resulting cover after watermarking is called watermarked cover18.
DEFINITIONS 3.1 Digital Libraries


A Digital Library (DL) is a collection of services and “information objects” that are available digitally. “Information objects” can be defined as anything in a digital format such as books, journal articles and sounds, since DLs organise and present information objects to users, and support them in dealing with these objects. The DL is the widely accepted term describing the use of digital technologies to acquire, store, preserve and provide access to information and material originally published in digital form or digitised from existing print, audio-visual and other forms. The above definitions reveal that a DL is a source of information, in different formats, e.g., text, video or audio, and that such information is stored digitally. Thus, the definition of DL is “a DL is a networked repository of digital content”. 3.2 Digital Watermarking
A Digital Watermarking (DWM) is a form of steganography in which copyright and other source information is hidden inside a document, image or sound file without the user’s knowledge, but copies will retain the information. It can prove authorship and track copies to the original owner.
A DWM is a digital signal or a pattern hidden directly in digital content. The digital content known as host 30 The watermarking of the document involves the transformation of the original into another form. It is contrasted with public-key encryption, which also transform original files into another form. It is a common practice now-a-days to encrypt digital documents so that they become un-viewable wi (...truncated)