Image Encryption by Using Block-Based Symmetric Transformation Algorithm (International Data Encryption Algorithm)

摘要

Today's world of communication is using image for message exchange also, may be one of the reason is that, text-based data is not that much secure until and unless we perform a good level of confusion-and diffusion-based encryption. In the case of image, security of image is a serious issue now-a-days because of ever increasing multimedia development, use, and associated brute force attacks. In the proposed paper, we are using IDEA (International Data Encryption Algorithm) as one of the strongest secret-key block ciphers by describing how IDEA can be used for image encryption before modifying the plaintext. The block cipher IDEA operates on 64-bit plaintext blocks, uses 128-bit key to give 64-bit cipher text blocks. We have used the pixel values of image to be encrypted. The proposed method consists of following five stages 1. Getting the pixel values of an image in two-dimensional plane. 2. Expending the 24-bit value of each pixel in 64-bit representation. 3. Applying IDEA algorithm over the 64-bit plaintext. 4. Adding eight bits at RHS to the generated 64-bit ciphertext in 24-bit. 5. Reallocating the color value from that 72-bit resultant in three pixel values.