Enhanced AES for Securing Hand Written Signature Using Residue Number System

The uncertainty and vulnerability of symmetric algorithm, Advanced Encryption Standard (AES), which uses a shared public secret key, however, timing attacks have called for a modification to it, to retain its potency and effectiveness. Residue Number System (RNS) has good potential in applications where speed and power consumption is very significant and with a carry-free propagation. To this effect, this paper focuses on the security of digital images based on hand written offline digital signature samples form CEDAR signatory images by enhancing the public key AES algorithm encryption and introducing RNS with three moduli which gives a three light weight image shares termed as residues. The study presents a hybrid method by further converting the encrypted images from the AES algorithm into residues using forward conversion technique with moduli of {2n − 2, 2n − 1, 2n + 1} into residues. Authentication stage involves conversion of residues to encrypted signatory using residue -to- binary (R/B) converters known as Chinese Remainder Theorem (CRT) by performing modular operations. Furthermore, the decryption stage utilizes inverse function going by the backward procedures involved in the encryption process. The AES + RNS model secured the digital signatory images stronger and further optimizes in terms of computation time, memory and throughput on both side of encryption and decryption and no constraint on image width or size with the advantage of dimensionality reduction and low power consumption of RNS to process the resultant image.