RSA-based Encryption Algorithm for Digital Images

With the spread of Covid-19, secure transmission of data over the Internet has drawn prior attention. Therefore, protecting these data is a very important process. This objective can be achieved through encryption. In this study, a digital image encryption algorithm is suggested depending on the RSA cryptosystem, since the RSA is a strong and well-known asymmetric encryption system. The proposed algorithm divides the image into blocks of 2×2 size rather than encrypting one pixel at a time. This improves the encryption process and then converts each block into a single vector. The vector elements are converted to binary and then into to a single binary number. After that, the binary number is converted to decimal to be compatible with using RSA algorithm. The proposed algorithm is lossless; the original image is restored without losing any information or data. Finally, the suggested algorithm is executed in MATLAB environment and tested on various images. The results of the experiment reveal the suggested encryption algorithm is both reliable, secure and applicable to image protection.