### On Entropy and Bit Patterns of Ring Oscillator Jitter

Markku-Juhani O. Saarinen

##### Abstract

Thermal jitter (phase noise) from a free-running ring oscillator is a common, easily implementable physical randomness source in True Random Number Generators (TRNGs). We show how to evaluate entropy, autocorrelation, and bit pattern distributions of ring oscillator noise sources, even with low jitter levels or some bias. Entropy justification is required in NIST 800-90B and AIS-31 testing and for applications such as the RISC-V entropy source extension. Our numerical evaluation algorithms outperform Monte Carlo simulations in speed and accuracy. We also propose a new lower bound estimation formula for the entropy of ring oscillator sources which applies more generally than previous ones.

Note: There is supplementary code available at: https://github.com/mjosaarinen/bitpat

Available format(s)
Category
Implementation
Publication info
Published elsewhere. MINOR revision.IEEE AsianHOST 2021
Keywords
Ring OscillatorEntropy SourceRandom NumbersStochastic ModelAIS-31NIST SP 800-90B
Contact author(s)
mjos @ mjos fi
History
2021-11-04: last of 5 revisions
See all versions
Short URL
https://ia.cr/2021/1363

CC BY

BibTeX

@misc{cryptoeprint:2021/1363,
author = {Markku-Juhani O.  Saarinen},
title = {On Entropy and Bit Patterns of Ring Oscillator Jitter},
howpublished = {Cryptology ePrint Archive, Paper 2021/1363},
year = {2021},
note = {\url{https://eprint.iacr.org/2021/1363}},
url = {https://eprint.iacr.org/2021/1363}
}

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