A metastable RNG using interleaved NAND- and NOR-based TEROs

ABSTRACT

This study introduces a novel approach to address the limitations observed in existing random number generator (RNG) designs, focusing on the resolution for insufficiently covered problem statements and study purposes. In response to these challenges, we propose a high-throughput metastable-based RNG tailored for cryptography applications. Our design is featured with a two-layer transient effect ring oscillator (TERO) architecture, meticulously crafted to mitigate the locking phenomenon and enhance RNG randomness. Leveraging interleaved two-layer TEROs, realised through NAND and NOR SR latches, our RNG achieves unpredictable irregular sampling, crucial for cryptographic applications. To further enhance irregular sampling, the first layer of the RNG employs a multiplexer that selects inputs randomly. This multiplexer is governed by selection signals generated by the second layer of the RNG, ensuring superior randomness. Implemented using TSMC 40-nm CMOS process, our RNG passed the FIPS 140–1 randomness test at a clock frequency of 100 MHz, boasting a remarkable throughput of 50 Mbps. This study represents a significant advancement in RNG technology, addressing previous shortcomings and paving the way for high-speed communication systems’ secure cryptographic applications.

KEYWORDS:

• Long run test
• metastable
• monobit test
• random number generator
• transient effect ring oscillator

Acknowledgments

The authors thank Taiwan Semiconductor Research Institute (TSRI) for the EDA tool assistance and chip fabrication.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded by National Science and Technology Council (NSTC), Taiwan, under grant NSTC 109-2218-E-110-007-, 109-2224-E-110-001-, and 111-2623-E-110-002-.