True-Randomness and Pseudo-Randomness in Ring Oscillator-Based True Random Number Generators

The paper deals with true random number generators employing oscillator rings, namely, with the one proposed by Sunar et al. in 2007 and enhanced by Wold and Tan in 2009. Our mathematical analysis shows that both architectures behave identically when composed of the same number of rings and ideal lo...

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Main Authors: Nathalie Bochard, Florent Bernard, Viktor Fischer, Boyan Valtchanov
Format: Article
Language:English
Published: Wiley 2010-01-01
Series:International Journal of Reconfigurable Computing
Online Access:http://dx.doi.org/10.1155/2010/879281
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author Nathalie Bochard
Florent Bernard
Viktor Fischer
Boyan Valtchanov
author_facet Nathalie Bochard
Florent Bernard
Viktor Fischer
Boyan Valtchanov
author_sort Nathalie Bochard
collection DOAJ
description The paper deals with true random number generators employing oscillator rings, namely, with the one proposed by Sunar et al. in 2007 and enhanced by Wold and Tan in 2009. Our mathematical analysis shows that both architectures behave identically when composed of the same number of rings and ideal logic components. However, the reduction of the number of rings, as proposed by Wold and Tan, would inevitably cause the loss of entropy. Unfortunately, this entropy insufficiency is masked by the pseudo-randomness caused by XOR-ing clock signals having different frequencies. Our simulation model shows that the generator, using more than 18 ideal jitter-free rings having slightly different frequencies and producing only pseudo-randomness, will let the statistical tests pass. We conclude that a smaller number of rings reduce the security if the entropy reduction is not taken into account in post-processing. Moreover, the designer cannot avoid that some of rings will have the same frequency, which will cause another loss of entropy. In order to confirm this, we show how the attacker can reach a state where over 25% of the rings are locked and thus completely dependent. This effect can have disastrous consequences on the system security.
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spelling doaj-art-484ccb40428642a8a69e5e6be3604eb32025-08-20T02:38:01ZengWileyInternational Journal of Reconfigurable Computing1687-71951687-72092010-01-01201010.1155/2010/879281879281True-Randomness and Pseudo-Randomness in Ring Oscillator-Based True Random Number GeneratorsNathalie Bochard0Florent Bernard1Viktor Fischer2Boyan Valtchanov3CNRS, UMR5516, Laboratoire Hubert Curien, Université de Lyon, 42000 Saint-Etienne, FranceCNRS, UMR5516, Laboratoire Hubert Curien, Université de Lyon, 42000 Saint-Etienne, FranceCNRS, UMR5516, Laboratoire Hubert Curien, Université de Lyon, 42000 Saint-Etienne, FranceCNRS, UMR5516, Laboratoire Hubert Curien, Université de Lyon, 42000 Saint-Etienne, FranceThe paper deals with true random number generators employing oscillator rings, namely, with the one proposed by Sunar et al. in 2007 and enhanced by Wold and Tan in 2009. Our mathematical analysis shows that both architectures behave identically when composed of the same number of rings and ideal logic components. However, the reduction of the number of rings, as proposed by Wold and Tan, would inevitably cause the loss of entropy. Unfortunately, this entropy insufficiency is masked by the pseudo-randomness caused by XOR-ing clock signals having different frequencies. Our simulation model shows that the generator, using more than 18 ideal jitter-free rings having slightly different frequencies and producing only pseudo-randomness, will let the statistical tests pass. We conclude that a smaller number of rings reduce the security if the entropy reduction is not taken into account in post-processing. Moreover, the designer cannot avoid that some of rings will have the same frequency, which will cause another loss of entropy. In order to confirm this, we show how the attacker can reach a state where over 25% of the rings are locked and thus completely dependent. This effect can have disastrous consequences on the system security.http://dx.doi.org/10.1155/2010/879281
spellingShingle Nathalie Bochard
Florent Bernard
Viktor Fischer
Boyan Valtchanov
True-Randomness and Pseudo-Randomness in Ring Oscillator-Based True Random Number Generators
International Journal of Reconfigurable Computing
title True-Randomness and Pseudo-Randomness in Ring Oscillator-Based True Random Number Generators
title_full True-Randomness and Pseudo-Randomness in Ring Oscillator-Based True Random Number Generators
title_fullStr True-Randomness and Pseudo-Randomness in Ring Oscillator-Based True Random Number Generators
title_full_unstemmed True-Randomness and Pseudo-Randomness in Ring Oscillator-Based True Random Number Generators
title_short True-Randomness and Pseudo-Randomness in Ring Oscillator-Based True Random Number Generators
title_sort true randomness and pseudo randomness in ring oscillator based true random number generators
url http://dx.doi.org/10.1155/2010/879281
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AT viktorfischer truerandomnessandpseudorandomnessinringoscillatorbasedtruerandomnumbergenerators
AT boyanvaltchanov truerandomnessandpseudorandomnessinringoscillatorbasedtruerandomnumbergenerators