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Tuesday, August 23rd, 2011

Dieharder Test

Categories: [ IT ]


It took about a week to generate a bit over 100 MB of random data with the arduino-based hardware random number generator. I used the JeeLink-based one, and the last chunk of random data (50 MB) was generated at a speed of 1562 bits/s.

And now for some statistical tests.

Fourmilab's ent test returns:

Entropy = 7.999998 bits per byte.
Optimum compression would reduce the size
of this 106315776 byte file by 0 percent.
Chi square distribution for 106315776 samples is 240.83, and randomly
would exceed this value 72.90 percent of the times.
Arithmetic mean value of data bytes is 127.4987 (127.5 = random).
Monte Carlo value for Pi is 3.140987091 (error 0.02 percent).
Serial correlation coefficient is 0.000165 (totally uncorrelated = 0.0).

I also ran the Dieharder test suite, which ran 40 tests on the data. Out of those, I got:

  • 34 PASSED
  • 1 POOR (1 RGB Bit Distribution Test out of 12 instances of the test)
  • 2 POSSIBLY WEAK (Diehard OPSO and Diehard Squeeze Test)
  • 3 FAILED (Diehard Sums Test and two instances of Marsaglia and Tsang GCD Test)

At the end of the series of tests, the software indicates that “The file file_input_raw was rewound 181 times”, meaning that I should get a lot more random data than 100 MB (ideally 18 GB, which means running the generator for 3.5 years) not to have the rewind the file for any of the tests.

The important question is however: 34 passed out of 40, is it good enough or not?

[ Posted on August 23rd, 2011 at 10:48 | 2 comments | ]

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Comment #2, Matthieu Weber (Jyväskylä, Finland), August 23rd, 2011 at 10:47

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