Fragile watermarking scheme based on SHA-256 hash function and mersenne twister for medical image authentication

Medical images can be easily manipulated by irresponsible persons and the altered medical image can be hard to identify. Fragile watermarking scheme is an alternative solution to authenticate and protect the medical images. Fragile watermarking scheme becomes vulnerable against modification by attackers. This research proposed a fragile watermarking scheme for medical images based onSHA-256 and Mersenne twister. A medical image was split into a region of interest (ROI) and region of non-interest (RONI). The ROI as watermarked image is encrypted by SHA-256 and the result is scrambled by Arnold transform with a secret key before embedding the watermark. The scrambled hash values are randomly embedded into RONI by using Mersenne Twister with a secret key. The experimental results showed that our scheme produces high imperceptibility with PSNR value of about 83 dB. The proposed scheme was able to detect tampers accurately on the medical images. The proposed scheme improved the invisibility of the watermarked image and it provided additional security. The proposed scheme authenticated and validated the originality of the medical images

Digital watermarking by utilizing the properties of self-organization map based on least significant bit and most significant bit

Information security is one of the most important branches concerned with maintaining the confidentiality and reliability of data and the medium for which it is transmitted. Digital watermarking is one of the common techniques in this field and it is developing greatly and rapidly due to the great importance it represents in the field of reliability and security. Most modern watermarking systems, however, use the self-organization map (SOM), which is safer than other algorithms because an unauthorized user cannot see the result of the SOM's training. Our method presents a semi-fragile watermark under spatial domain using least significant bit (LSB) and by relying on most significant bit (MSB) when the taken values equal to (2 or 4 bits) depending on the characteristics of SOM through developing the so-called best matching unit (BMU) which working to determine the best location for concealment. As a result, it shows us the ability of the proposed method to maintain the quality of the host with the ability to retrieve data, whether it is a binary image or a secret message

Cellular Automata Based Image Authentication Scheme Using Extended Visual Cryptography

Most of the Visual Cryptography based image authentication schemes hide the share and authentication data into cover images by using an additional data hiding process. This process increases the computational cost of the schemes. Pixel expansion, meaningless shares and use of codebook are other challenges in these schemes. To overcome these issues, an authentication scheme is proposed in which no embedding into the cover images is performed and meaningful authentication shares are created using the watermark and cover images. This makes the scheme completely imperceptible. The watermark can be retrieved just by superimposing these authentication shares, thus reducing the computational complexity at receiver's side. Cellular Automata is used to construct the master share that provides self-construction ability to the shares. The meaningful authentication shares help in enhancing the security of the scheme while size invariance saves transmission and storage cost. The scheme possesses the ability of tamper detection. Experimental results demonstrate the improved security and quality of the generated shares of the proposed scheme as compared to existing schemes