Cryptography of a Gray Level Image using a Novel Block Cipher Involving Feistel Structure and Modular Arithmetic

In this paper, we have made use of a novel block cipher involving Feistel structure and modular arithmetic for encrypting a Gray levelimage. The image is represented in the form of a matrix of size 256 x 256, and this is divided into 32 parts, wherein each part is of size 32 x 64. A key of size 8 x 8 is taken and it is transformed into a key of size 32 x 32. This key is utilised in carrying out the computations required forencryption and decryption. As the cipher is a strong one, we find that no one can identify the original image by any means