Low‐cost TRNG IPs

Abstract

This study presents a low-cost multi-throughput true random number generator (TRNG) intellectual property (IP) based on a variable-length multi-mode ring oscillator. The proposed TRNG implements a multi-throughput feature by bypassing inverter cells in the ring oscillator for reducing the loop delay. This multi-throughput feature offers the advantage of high-performance or low-power operation when needed. These options make the proposed TRNG suitable for end-to-end encryption in highly restricted devices such as Internet of Things sensor nodes. Measurement results show that the proposed TRNG passes national institute of standards and technology (NIST) tests for different throughput operations. The TRNG is embedded in a reduced instruction set computer V (RISC-V)-based system-on-chip (SoC) for periodical-driven applications, and it achieves an energy efficiency of 92 pJ at 3.7 Mbps, occupying 58 μ m × 150 μ m in a 180 nm technology. This study also presents a system technique to implement the entropy enhanced TRNGs, using multiple entropy sources. An extraction system provides high-quality random numbers with a sampling method that takes one entropy output to sample the other entropy sources. The system requires few resources, using low-cost TRNG IPs as entropy sources.