Building a Modern TRNG: An Entropy Source Interface for RISC-V

Saarinen Markku-Juhani O., G. Richard Newell, Ben Marshall

Research output: Contribution to conferenceConference Paperpeer-review


The currently proposed RISC-V True Random Number Generator (TRNG) architecture breaks with previous ISA TRNG practice by splitting the Entropy Source (ES) component away from cryptographic PRNGs into a separate interface, and in its use of polling. We describe the interface, its use in cryptography, and offer additional discussion, background, and rationale for various aspects of it. This design is informed by lessons learned from earlier mainstream ISAs, recently introduced SP 800-90B and FIPS 140-3 entropy audit requirements, AIS 31 and Common Criteria, current and emerging cryptographic needs such as post-quantum cryptography, and the goal of supporting a wide variety of RISC-V implementations and applications. Many of the architectural choices are a result of quantitative observations about random number generators in secure microcontrollers, the Linux kernel, and cryptographic libraries. We further compare the architecture to some contemporary random number generators and describe a minimalistic TRNG reference implementation that uses the Entropy Source together with RISC-V
AES instructions.
Original languageEnglish
Publication statusPublished - Nov 2020
Event4th Workshop on Attacks and Solutions in Hardware Security - Virtual Event
Duration: 13 Sep 2020 → …


Workshop4th Workshop on Attacks and Solutions in Hardware Security
Abbreviated titleASHES’20
Period13/09/20 → …
Internet address


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