Markov Matrix and Entropy based Tamper Detection Technique for Text Images

In this paper, a novel watermarking technique for the tamper detection of text images is pro- posed. Entropy of every sentence is computed and Markov matrix using the occurrences of the characters is used to generate a character pattern. Entropy and character patterns are converted to Unicode Zero Width Characters (ZWCs) by using a lookup table. The ZWCs of entropy of each sentence is embedded at the end of every sentence after terminator. ZWCs of the character patterns are embedded in the end of the text of the image. On receiver side, ZWCs are extracted and converted to numerical form using the same lookup table. Entropy of every sentence and character patterns are recalculated and compared with extracted values for tamper detection. Comparison of technique with existing state-of-art techniques shows the effectiveness of the proposed technique.

Image Forensic Tool (IFT)

Images now-a-days are often used as an authenticated proof for any cyber-crime. Images that do not remain genuine can mislead the court of law. The fast and dynamically growing technology doubts the trust in the integrity of images. Tampering mostly refers to adding or removing important features from an image without leaving any obvious trace. In earlier days, digital signatures were used to preserve the integrity, but now a days various tools are available to tamper digital signatures as well. Even in various state-of-the-art works in tamper detection, there are various restrictions in the type of inputs and the type of tampering detection. In this paper, the researchers propose a prototype model in the form of a tool that will retrieve all the image files from given digital evidence and detect tampering in the images. For various types of tampering, different tampering detection algorithms have been used. The proposed prototype will detect if tampering has been done or not and will classify the image files into groups based on the type of tampering.