A Lightweight TRNG Based on First‐Order‐Oscillator‐Obfuscated Cross‐Coupled Logic Gates

ABSTRACT With the rapid development of the Internet of Things (IoT), the design of field‐programmable gate array (FPGA)–based lightweight true random number generators (TRNGs) has garnered increasing attention. This paper proposes a TRNG based on the first‐order‐oscillator‐obfuscated cross‐coupled logic gate (OCCLG) unit. The TRNG utilizes a first‐order oscillator to configure the cross‐coupled logic gates within each OCCLG unit, while the fast oscillation generated by the oscillator further obfuscates the output of the XOR‐gate coupling logic. The proposed TRNG consists of six circularly cascaded OCCLG units, whose outputs are sampled by six DFFs through an XOR gate to generate a random bit sequence. Implemented on Artix‐7 and Zynq‐7000 FPGA development boards using automated place‐and‐route, the proposed TRNG delivers a remarkable throughput of 325 Mbps, requiring only 25 LUTs, 6 DFFs, and a power budget of 23 mW, which indicates superior resource efficiency. Experimental results confirm that the output random sequence successfully passes the NIST SP800‐22 test suite, the NIST SP800‐90B tests, and the AIS‐31 tests. It also demonstrates strong robustness against voltage and temperature variations, as well as frequency injection attacks.