Digital watermarking

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DIGITAL WATERMARKING

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INTRODUCTION:-

Think of a multimedia data that is being distributed over the Internet.

Someone downloads it , claims it that he has the copyright, and sells it. In these kinds of situations, digital watermarking techniques can be used for establishing ownership rights, ensuring authorized access, preventing illegal reapplication and facilitating content authentication.

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“Digital watermarking is the process of embedding information into a digital signal in a way that is difficult to remove.”

The signal may be audio, pictures or video, for example. If the signal is copied, then the information is also carried in the copy. A signal may carry several different watermarks at the same time.

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General Procedure for Digital Watermarking:

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WATERMARKING LIEF-CYCLE

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ATTACKS:-

Attacks on watermark may not necessarily remove the watermark, but disable its readability. Image processing and transforms are commonly employed to create and apply watermarks.

These same techniques can also be used to disable or overwrite watermarks. Multiple watermarks can be placed in an image and one cannot determine which one is valid. Currently watermark registration service is "first come, first served." Someone other than the rightful owner may attempt to register a copyright first.

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TYPES OF ATTACKS ON WATERMARKS Removal attacks Geometrical attacks Cryptographic attacks Protocol attacks

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TYPES OF WATERMARK:

(1)ROBUST WATERMARK: A robust watermark is a watermark that is difficult to remove from the object in which it is embedded.

(2)FRAGILE WATERMARK: A fragile watermark is destroyed if anybody attempts to tamper with the object in which it is embedded.

(3)VISIBLE WATERMARK: A visible watermark is immediately perceptible and clearly identifies the cover object as copyright-protected material, much like the copyright symbols ã, â, and ä

(4)INVISIBLE WATERMARK: An invisible watermark is not normally perceptible, but can still be used by the rightful owner as evidence of data authenticity in a court of law.

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Important Parameters

Transparency Robustness Security Capacity Invertibility (reversibility) Complexity Possibility of verification

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Common watermarking techniques

Choice of Watermark Object Time domain-LSB Modification Frequency Domain Wavelet Domain

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APPLICATION

Owner identification and proof of ownership

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Broadcast monitoring Transaction tracking Usage control

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CONCLUSION:-

Digital watermarking has emerged as an essential security technology, fully complementary to encryption-based secure transmission and copy protection.

This technology is widely applicable to almost all electronic information services and systems where data protection, security, and intellectual property rights are needed.

However, effective uses in fields such as digital camera, DVD, digital broadcasting, electronic commerce, and law enforcement have not been explored.

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