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diff --git a/content/RandomnessTesting.md b/content/RandomnessTesting.md index 6d8fdc7..29001c8 100644 --- a/content/RandomnessTesting.md +++ b/content/RandomnessTesting.md @@ -21,17 +21,17 @@ Dieharder is by far the most extensive blackbox test suite. However, it is orig Generally the best approach to use `dieharder` is to first generate an output file, e.g. `random.out` to run the tests on, so `dieharder` can apply all its individual tests to the same data. For a standard test, at least about 14 GB worth of data are needed; more if one of the tests needing large amounts of data returns a suspect result and `dieharder` re-tries the same test with more data. The command line options I (bs) personally use are `dieharder -g 201 -f random.out -s 1 -Y 1 -k 2 -a`: - -g 201 -f random.out:: Don't use a compiled-in pseudo RNG but the file `random.out` as input. - -s 1:: Rewind the input after every test. Without this, successive tests use successive parts of the input file. - -Y 1:: Keep testing until a definite (in probabilistic terms:-) test result is obtained. - -k 2:: Use some high precision numerics for the KS test; recommended by the man page. - -a:: Run all tests. +* `-g 201 -f random.out`: Don't use a compiled-in pseudo RNG but the file `random.out` as input. +* `-s 1`: Rewind the input after every test. Without this, successive tests use successive parts of the input file. +* `-Y 1`: Keep testing until a definite (in probabilistic terms:-) test result is obtained. +* `-k 2`: Use some high precision numerics for the KS test; recommended by the man page. +* `-a`: Run all tests. Additionally, these may be useful for more targeted testing: - -m <n>:: Multiply the `psamples` value by `n`; good for getting even more reliable results, at the expense of the additional data needed. - -d <test name/number>:: Perform a specific test. - -l:: List all available tests by name and number. - -p <n>:: Set the `psamples` value. See below why you may need this. +* `-m <n>`: Multiply the `psamples` value by `n`; good for getting even more reliable results, at the expense of the additional data needed. +* `-d <test name/number>`: Perform a specific test. +* `-l`: List all available tests by name and number. +* `-p <n>`: Set the `psamples` value. See below why you may need this. ### Interpretation of Results The way `dieharder` works, it simply returns a clear assessment of the test results; interpretation should be immediately obvious. @@ -56,12 +56,13 @@ They generally work on blocks of 20000 bits. ### Usage The `rngtest` program reads data from its standard input and by default returns a statistics overview when it reaches EOF. This can be changed with these two options (among others): - -c <n>:: Stop running after `n` blocks. - -b <n>:: Give intermediate results every `n` blocks. +* `-c <n>`: Stop running after `n` blocks. +* `-b <n>:` Give intermediate results every `n` blocks. Use at least one of these when running on a pipe or device... ### Interpretation of Results Since `rngtest` works on rather small sample sizes it causes a significant number of false alarms: + | Test | Expected failure rate | |---|---| | Total | 800ppm | @@ -74,9 +75,3 @@ Since `rngtest` works on rather small sample sizes it causes a significant numbe These failure rates were however measured experimentally rather than derived from the algorithms themselves, so caveat utilitor. Seriously flawed inputs often show excessive failures from very small input; it is generally a good idea to keep testing until at least about 100 failures in total have occurred before seriously comparing the measured results to the expected failure rates from the table. - - - - - - |