Introduction nformation hiding can be mainly divided into three processes -cryptography, steganography and watermarks. Cryptography is the process of converting information to an unintelligible form so that only the authorized person with the key can decipher it. As many advances were made in the field of communication it became rather simple to decrypt a cipher text. Hence more sophisticated methods were designed to offer better security than what cryptography could offer. This led to the discovery of stenography and watermarking. Stenography is the process of hiding information over a cover object such that the hidden information cannot be perceived by the user. Thus even the existence of secret information is not known to the attacker. Watermarking is closely related to steganography, but in watermarking the hidden information is usually related to the cover object. Hence it is mainly used for copyright protection and owner authentication. Digital watermarking is the process of embedding information into digital multimedia content such that the information (the watermark) can later be extracted or detected for a variety of purposes including copy prevention and control. Digital watermarking has become an active and important area of research, and development. Key research problem that we still face today is the development of truly robust, transparent and secure watermarking technique for different digital media including images, video and audio. So we propose a new robust digital watermarking system based on DCT and fuzzy vault techniques # PRINCIPLE OF WATERMARKING A watermarking system is usually divided into three distinct steps, embedding, attack and detection. In embedding, an algorithm accepts the host and the data to be embedded and produces a watermarked signal. The watermarked signal is then transmitted or stored, usually transmitted to another person. If this person makes a modification, this is called an attack. There are many possible attacks. Detection is an algorithm which is applied to the attacked signal to attempt to extract the watermark from it. If the signal was not modified during transmission, then the watermark is still present and it can be extracted. If the signal is copied, then the information is also carried in the copy. The embedding takes place by manipulating the content of the digital data, which means the information is not embedded in the frame around the data, it is carried with the signal itself. The watermark is visible which can be a text or a logo used to identify the owner. Any text or logo to verify or hide content. # III. # Digital watermarking technology The watermark is embedded into the image in such a way that it cannot be perceived by human eye. It is used to protect the image authentication and prevent it from being copied. Invisible watermark can be further divided into three types, Invisible watermark cannot be manipulated without disturbing the host signal. This is by far the most important requirement of a watermark. There are various attacks, unintentional (cropping, compression, scaling) and unintentional attacks which are aimed at destroying the watermark. So, the embedded watermark should be such that it is invariant to various such attacks. They are designed to resist any manipulations that may be encountered. All applications where security is the main issue use robust watermarks. They are designed with very low robustness. They are used to check the integrity of objects. They are differentiated in accordance with the secrecy requirements for the key used to embed and retrieve watermarks. If the original image is not known during the detection process then it is called a public or a blind watermark and if the original image is known it is called a non blind watermark or a private watermark. # IV. # System architecture a) Embedding Watermark This module is designed to insert the fuzzy vault into the host image. The fuzzy vault is combination of set of genuine points and set of chaff points. Secret data is used to construct the polynomial. In this module first we extract minutiae features from fingerprint image. And these features are further used to project the polynomial then set of genuine points and chaff points is calculated. And the union of set of genuine points and chaff points is nothing but the fuzzy vault.For inserting the fuzzy vault into an image DCT is applied on that image and to get the watermarked image IDCT is applied. In this module secret data is extracted by using the watermarked image and fingerprint image to validate the user. Again the DCT is applied on the watermarked image and fuzzy vault is extracted from that image. And minutiae features are extracted from the fingerprint image. By comparing the minutiae features and fuzzy vault candidate points are calculated. And then applying Langrange Interpolation CRC is calculated. If the CRC is correct then we get the secret data that proves that the user is valid user. # V. APPLICATION In this project, an efficient blind digital image watermarking algorithm using mapping technique is presented. The algorithm can embed or hide an entire image or pattern (logo) directly into the original image. The embedding process is based on changing the selected DCT coefficients of the host image to odd or even values depending on the binary bit value of watermark DCT coefficients. The algorithm is tested for fingerprint image embedded with a face watermark. It is demonstrated that the watermarking algorithm offers a significant advantage of providing biometric image compression and authentication without introducing any significant degradation in the image quality. Moreover the watermarking scheme is blind and does not require any additional data for logo extraction. # Applications of image watermarking: a) Copyright Protection This is by far the most prominent application of watermarks. With tons of images being exchanged over insecure networks every day, copyright protection becomes a very important issue. Watermarking an image will prevent redistribution of copyrighted images. # b) Authentication Sometimes the ownership of the contents has to be verified. This can be done by embedding a watermark and providing the owner with a private key which gives him an access to the message. ID cards, ATM cards, credit cards are all examples of documents which require authentication. # c) Broadcast Monitoring As the name suggests broadcast monitoring is used to verify the programs broadcasted on TV or radio. It especially helps the advertising companies to see if their advertisements appeared for the right duration or not. # d) Content Labeling Watermarks can be used to give more information about the cover object. This process is named content labeling. # e) Tamper Detection Fragile watermarks can be used to detect tampering in an image. If the fragile watermark is degraded in any way then we can say that the image or document in question has been tampered. # f) Digital Fingerprinting This is a process used to detect the owner of the content. Every fingerprint will be unique to the owner. # g) Content Protection In this process the content stamped with a visible watermark that is very difficult to remove so that it can be publicly and freely distributed. # CONCLUSION With the popularity of the network, the safety communication issue of digital product becomes an important and urgent research topic. The basic principles and algorithms of the digital watermarking technology are discussed, and the DCT algorithm is selected to do the application test of digital image copyright protection. The experiment proves that DCT-based watermark can well withstand a variety of image processing, and the watermark can survive after compression, cropping, and other attacks. Digital watermarking technology can provide a new way to protect the copyright of multimedia information and to ensure the safe use of multimedia information. Comparing to the traditional information security technology, digital watermarking technology has its own advantages in the multimedia information security protection. Then it can meet the application need in many aspects and has a bright development prospect. 1![Figure 1: Types of Steganography](image-2.png "Figure 1 :") ![As an Emerging Interdisciplinary application Technology, Digital Watermarking Involves the Ideas and Theories of Different Subject Coverage Such as Signal Processing, Cryptography, Probability Theory, Network Theory Algorithm Design, and other techniques. a) Classfication of Digital Watermarking](image-3.png "") 2![Figure 2: Embedding watermark b) Extracting Watermark](image-4.png "Figure 2 :") 317![Figure 3: Extracting watermark Global Journal of Computer Science and Technology Volume XII Issue IX Version I 16](image-5.png "Figure 3 : 1 . 7 .") © 2012 Global Journals Inc. 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