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Entropy Evaluation for Oscillator-Based True Random Number Generators

  • Yuan Ma
  • Jingqiang Lin
  • Tianyu Chen
  • Changwei Xu
  • Zongbin Liu
  • Jiwu Jing
Part of the Lecture Notes in Computer Science book series (LNCS, volume 8731)

Abstract

True random number generators (TRNGs) are crucial to the implementations of cryptographic algorithms and protocols. The quality of randomness directly influences the security of cryptographic systems. Oscillator-based sampling is popular in the design of TRNGs due to its nice properties of elegant structure and high speed. However, the credibility of randomness generated from high-speed oscillator-based TRNGs, especially ring oscillator-based (RO-based) ones, is still in controversy. This is mainly because pseudo-randomness is hardly distinguished from true randomness and RO-based TRNGs are susceptible to external perturbations. In this paper, we present a stochastic model to evaluate the entropy of oscillator-based TRNGs, and then deduce the requirement of design parameters (including the sampling interval) for sufficient entropy per random bit, i.e., to ensure true randomness. Furthermore, we design a jitter measuring circuit to verify the theory, and the theoretical results are confirmed by both the simulation and practical experiments. Finally, we apply the stochastic model to analyze the effect of deterministic perturbations, and demonstrate that the randomness of RO-based TRNGs (under deterministic perturbations) can be overestimated and predicting the “random” bits could be possible.

Keywords

True random number generators ring oscillators sufficient entropy perturbation stochastic model 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Yuan Ma
    • 1
    • 2
  • Jingqiang Lin
    • 1
    • 2
  • Tianyu Chen
    • 1
    • 2
  • Changwei Xu
    • 1
    • 2
  • Zongbin Liu
    • 1
    • 2
  • Jiwu Jing
    • 1
    • 2
  1. 1.Data Assurance and Communication Security Research CenterChinese Academy of SciencesBeijingChina
  2. 2.State Key Laboratory of Information Security, Institute of Information EngineeringChinese Academy of SciencesBeijingChina

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