Problem - Kevin Tafuro

For this reason, we think the full suite of FIPS 140-1 tests is the way to go any time
you really want to test whether an entropy source is producing good data, and it is a
good idea to run these tests on startup, and then periodically, when feasible. You
should always support the continuous test that FIPS 140-2 mandates whenever you
are using hardware random number generators that could possibly be prone to disastrous
failure, because it might help you detect such a failure.
FIPS 140-1 power-up and on-demand tests
The FIPS 140-1 standard specifies four statistical tests that operate on 20,000 consecutive
bits of output (2,500 bytes).
In the first test, the “Monobit” test, the number of bits set to 1 are counted. The test
passes if the number of bits set to 1 is within a reasonable proximity to 10,000. The
function spc_fips_monobit( ), implemented as follows, performs this test, returning 1
on success, and 0 on failure.
#define FIPS_NUMBYTES 2500
#define FIPS_MONO_LOBOUND 9654
#define FIPS_MONO_HIBOUND 10346
/* For each of the 256 possible bit values, how many 1 bits are set? */
static char nb_tbl[256] = {
0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3,
4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4,
4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2,
3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5,
4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3,
4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3,
3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5,
6, 6, 7, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6,
4, 5, 5, 6, 5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 4, 5, 5,
6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
};
int spc_fips_monobit(unsigned char data[FIPS_NUMBYTES]) {
int i, result;
for (i = result = 0; i < FIPS_NUMBYTES; i++)
result += nb_tbl[data[i]];
return (result > FIPS_MONO_LOBOUND && result < FIPS_MONO_HIBOUND);
}
The second test is the “Poker” test, in which the data is broken down into consecutive
4-bit values to determine how many times each of the 16 possible 4-bit values appears.
The square of each result is then added together and scaled to see whether the result
falls in a particular range. If so, the test passes. The function spc_fips_poker( ), implemented
as follows, performs this test, returning 1 on success and 0 on failure:
#define FIPS_NUMBYTES 2500
#define FIPS_POKER_LOBOUND 1.03
Statistically Testing Random Numbers | 617
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