FIPS Standard

A run is defined as a maximal se
quence of consecutive bits of either all ones or all zeros that is part of the
20,000 bit sample stream. The incidences of runs (for both consecutive zeros and consecutive ones) of all
lengths (≥ 1) in the sample stream should be counted and stored.
The
test is passed if the runs that occur (of lengths 1 through 6) are each within the corresponding interval
specified in the table below. This must hold for both the zeros and ones (i.e., all 12 counts must lie in the
specified interval). For the purposes of this test, runs of greater than 6 are considered to be of length 6.
Length of
Run
Required
Interval
1 2,343 – 2,657
2 1,135 – 1,365
3 542 - 708
4 251 - 373
5 111 - 201
6+ 111 - 201
Table 3.
Required intervals for length of runs test
The long runs test
A long run is defined to be a run of length
26 or more (of either zeros or ones).
On the sample of 20,000 bits, the test is passed if there are no long runs.
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