3. An Optimal Lightweight RECTANGLE Block Cipher for Secure Image Transmission in Wireless Sensor Networks

The fast development of networking permits substantial documents, for example, multimedia images, to be effectively transmitted over the Wireless Sensor Networks (WSNs). An image encryption is generally used to guarantee the security as it may secure the images in the greater part. The process of securing the images in WSN against unauthorized users is a challenging one. For guaranteeing high security among Digital Images (DIs), Light Weight Cryptographic (LWC) algorithms are utilized which split the DI into a number of blocks; this will upgrade the level of security in WSN. Here, the proposed block cipher is RECTANGLE which separates the image in a bit-slice style; and improves the DI security level by encryption and decryption depending on the determination of optimal public key and private key individually. The key optimization was finished by the metaheuristic algorithm, for example, Opposition-based Grey Wolf Optimization (OGWO) which chosen optimal key on the basis of the most extreme PSNR value. The exhibited RECTANGLE–OGWO accomplished the least time to produce key which remained as an incentive to encrypt and decrypt the image. The result showed that the RECTANGLE–OGWO algorithm enhanced the accuracy of DI security for all the images (Lena, Barbara, Baboon, Airplane and House) when contrasted with existing algorithms.