Cryptographic Randomness from Air Turbulence in Disk Drives

  • Don Davis
  • Ross Ihaka
  • Philip Fenstermacher
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 839)


A computer disk drive’s motor speed varies slightly but irregularly, principally because of air turbulence inside the disk’s enclosure. The unpredictability of turbulence is well-understood mathematically; it reduces not to computational complexity, but to information losses. By timing disk accesses, a program can efficiently extract at least 100 independent, unbiased bits per minute, at no hardware cost. This paper has three parts: a mathematical argument tracing our RNG’s randomness to a formal definition of turbulence’s unpredictability, a novel use of the FFT as an unbiasing algorithm, and a “sanity check” data analysis.


Disk Drive Weak Turbulence Sanity Check Taylor Vortex Flow Disk Controller 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1994

Authors and Affiliations

  • Don Davis
    • 1
  • Ross Ihaka
    • 2
  • Philip Fenstermacher
    • 3
  1. 1.Openvision TechnologiesCambridge
  2. 2.Mathematics DeptUniversity of AucklandAuckland
  3. 3.Cambridge

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