A Novel Lightweight Image Cryptographic Algorithm via Substitution‐Permutation Methods

ABSTRACT In this era of ubiquitous computing, there is an abrupt increase in the transmission of multimedia, including images, audio, video, and so forth, through communication channels. The attackers try to intercept confidential data transferred through these channels, resulting in serious security breaches. Hence, there is an imperative necessity for efficient and reliable image transmission to secure the confidential image data against malicious attacks. To counter these attacks, image cryptography is a viable solution for protecting image data from unauthorized access. In this research work, we propose a lightweight block‐cipher‐inspired image encryption technique by employing a designed substitution‐permutation network using an improved S‐box. The constructed substitution box is evaluated using standard criteria, including nonlinearity, autocorrelation, balance, differential uniformity, bit independence criteria, differential approximation probability (DAP), and linear approximation probability (LAP). Our technique employs elementary operations such as XOR, shift operations, and division of blocks, which makes the algorithm less complex. The experimental results show the efficacy of the presented image cipher in terms of various metrics and outperform various existing lightweight approaches, with a correlation coefficient of 0.01853, a structural similarity index measure (SSIM) of 0.0197, a peak signal‐to‐noise ratio (PSNR) of 27.809 dB, a number of pixels change rate (NPCR) of 99.65%, and a unified average changing intensity (UACI) of 29.97%. Moreover, the proposed cipher is efficient in terms of gate equivalence for hardware implementation in constraint devices (i.e., CCTV) and results in low latency for encryption or decryption. The cryptanalysis of the cipher via linear or differential methods demonstrates its resilience against various attacks.