Open AccessPublished: Oct 17, 2026ONB-En 2.0: A Hardware-Optimized Lightweight Cipher with Bit-Sliced S-Boxes for IoT Security
Abstract.The deployment of the Internet of Things (IoT) has left a strong demand on lightweight cryptography. Security and efficiency algorithms on resource-constrained platforms. The given paper introduces the ONB-En 2.0, the improved variant of the ONB-En lightweight block cipher, which resolves the linearity issues that the predecessor was limited to by introducing the nonlinear elements in a very cautious manner. We develop a bit-sliced 4×4 S-box designing modelled by PRESENT, coupled with an optimized permutation layer that maintains hardware achievement while markedly improving resistance against differential and linear cryptanalysis. Our comprehensive security analysis demonstrates that ONB-En 2.0 achieves 10 rounds of security with differential probability bounded by 2−48 and linear bias magnitude below 2−24. Hardware implementation results on Xilinx Artix-7 FPGA show that ONB-En 2.0 requires only 1,247 gate equivalents (GE) with a throughput of 156.2 Mbps at 100 MHz, achieving 125 Kbps/GE efficiency. Comparative analysis against PRESENT, GIFT-128, and SPECK demonstrates that ONB-En 2.0 offers superior hardware efficiency while maintaining cryptographic strength suitable for IoT applications, including wireless sensor networks, RFID systems, and embedded secure communications.