With the advent of internet, creation and delivery of digital data (images, video and audio files, digital repositories and libraries, web publishing) has grown many fold. Along with it, issues like protection of rights of content and proving ownership arises.Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, has the knowledge of the existence of the message, a form of security through obscurity. Watermarking, a part of steganography is often applied for protection of messages.Watermarking has come up as a tool to overcome shortcomings of current copyright laws for digital data. To prove ownership and protect rights, a watermark is embedded in the data. Also to save watermark from counterfeiters we need to find the locations which are invariant to any kind of attack (rotation, expansion, compression, cropping, filtering, and blurring).Every image has regions, also known as patches, which are invariant to attacks. These patches can be found by using Scale Invariant Feature Transform (SIFT) over image. As these patches are very stable and resistant to attacks, watermark is inserted in these patches. During decryption these watermarks can also be successfully extracted with low error probability. The algorithms can be strengthened using visible watermark technique.

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