## Processor Flutter - Part 3

The numerical results of the R analysis in

part 2
are summarized below:

Processor |
bogomips |
Log Mean |
Log SD |
Log 1st Q |
Log 3rd Q |
Mean |
1st Q |
3rd Q |

I7 |
6731.54 |
2.006 |
0.2162 |
1.851 |
2.161 |
101 |
71 |
145 |

Xeon |
5984.78 |
2.745 |
0.098 |
2.681 |
2.799 |
556 |
480 |
630 |

Pentium |
4793.92 |
5.984 |
2.4142 |
4.724 |
7.827 |
963,829 |
52,966 |
67,142,855 |

The "INJECT" feature of the haveged diagnostic build can be used to verify the sanity
check on the previous conclusions. Injection replaces haveged timer readings with values
read from an input file. This produces output which can then be analyzed by the usual
tools used to validate haveged output. In particular, CAPTURE data can be injected into
haveged to indeed insure that the data sequence does pass the haveged statistical tests
(ent and a subset of the NIST test).

The CAPTURE data in three test cases above pass both ent and NIST tests. The log-normal
proposition can be tested by replacing the CAPTURE data with the proposed distribution.
This is done by generating a normal distribution using the mean and sd values tablulated
below in R and then saving the anti-log (10^value) of the value in an injection file.

Data thus synthesized for three test cases above also passes both ent and NIST tests. The
synthesized distributions are shown below using a log scale. Even with the log scale
compression, the tail of the Pentium distribution had to be trimed to show any detail. This
exaggerates the y axis of that plot by a factor of roughly 10.

### Conclusions

The results contain encouragement that the haveged noise source does have the
characteristics of a distribution created as the product of independent timing
effects. This result must be tempered with the obvious appearance of “edge”
effects which in the Pentium case seem to be comparable to the actual timing
variation. More secure conclusions must await a more detailed analysis of the
havege “whitener” to determine the actual uncertainty/bit of the output.

Home