Digital Signature Scheme for Image

Image authentication techniques have currently added great consideration due to its importance for a large number of multimedia applications. Digital images are progressively communicated over non-secure channels such as the Internet. Therefore, military, medical and quality control images must be protected against attempts to manipulate them; such manipulations could tamper the decisions based on these images. To protect the authenticity of multimedia images, several approaches have been proposed. These methods comprise conformist cryptography, fragile and semi-fragile watermarking and digital signatures that are based on the image content. The purpose of this paper is to present evolving technique for image authentication. It also familiarizes the new concept of image content authentication and deliberates the most important requirements for an effective image authentication system design. Methods which are discussed provide strict or selective authentication, tamper detection, localization and reconstruction capabilities and robustness against different anticipated image processing operations.