Digital Forensic Enabled Image Authentication Using Least Significant Bit (LSB) with Tamper Localization Based Hash Function

Abstract

Addition of hash component in a message is always for verification of authentication of message without integrity. In order to retain integrity certain schemes such as Merkle–Damgard scheme or Rabin scheme based on the block cipher can be used. However, the block cipher schemes in messages do not get applicable on image which are encoding message in a visual format. Therefore, block cipher based schemes are not able to provide tamper localization in case of image authentication. Tamper detection is needed in case of images as it is not visualized without proper verification. Moreover, localization is not possible by hash verification making the authentication processes only detectable but not identifiable. The paper presents a generation process of three least significant bits of hash function. The image insertion is not visualized due to human eye limitation. The method proposed is able to embed a secret image (gray scale) inside a corner image. Experimental results show an improvement in peak signal-to-noise ratio (PSNR) values of the proposed technique over the other techniques available, such as hash-based LSB(2-3-3) image steganography in spatial domain. This paper proposes an image authentication process not only for robustness, security, and tamper detection but also successfully able to identify tamper by a process of tamper localization. The parameters compared include the classical mechanism along with newly introduced entropy measurement of images. A performance analysis is able to show the result claimed in the paper. The paper uses a least significant bit (LSB) based hash function, which is a blind technique as image-related information is never sent to receiver separately. In fact, the proposed approach is a clever design as the generated hash function will be embedded in the image itself. The proposed mechanism is able to offer good imperceptibility between original image and embedded image with hash bits. Even a minute tampering can be detected with proper localization; the localization of tampering is having its wide applicability in case of forensic evidence of malicious image morphing.