Novel image encryption using significant bits of blocks of gray image with new random number generator

Abstract Image encryption is an effective technique for protecting image content. In this paper, we introduce a novel gray image encryption algorithm that integrates PLCM, Random division of blocks, double permutation, Significant Bits manipulation, and the Piecewise Exponential Function (PEF) as a new random number generator. Initially, the input image is divided into random blocks by PLCM, and the pixels within each block are rearranged using permutation pattern and then put all the blocks back in place and then again apply permutation over the whole image which will give us the permuted image. Secret keys are used to generate random matrix by PEF chaotic map, which produces a random matrix of the same size as the input image. Divide permuted image and random matrix into most significant bit (MSB) and least significant bit (LSB). Finally, the encrypted image is obtained by applying an XOR operation between ( $${MSB}_{P}\oplus {LSB}_{R} \; and \; {LSB}_{P} \oplus {MSB}_{R})$$ the permuted image and the generated random matrix. The experimental outcome proves the proposed algorithm generates strong encryption and performs better than multiple well-known encryption algorithms.