Problem - Kevin Tafuro

}
int cur_val, i, j, runsz;
unsigned char curr;
for (cur_val = i = runsz = 0; i < FIPS_NUMBYTES; i++) {
curr = data[i];
for (j = 0; j < 8; j++) {
/* Check to see if the current bit is the same as the last one */
if ((curr & 0x01) ^ cur_val) {
/* The bits are different. A run is over, and a new run of 1 has begun */
if (runsz >= FIPS_LONGRUN) return 0;
if (runsz > 6) runsz = 6;
runs[cur_val][runsz]++;
runsz = 1;
cur_val = (cur_val + 1) & 1; /* Switch the value. */
} else runsz++;
curr >>= 1;
}
}
return (runs[0][1] > FIPS_RUNS_1_LO && runs[0][1] < FIPS_RUNS_1_HI &&
runs[0][2] > FIPS_RUNS_2_LO && runs[0][2] < FIPS_RUNS_2_HI &&
runs[0][3] > FIPS_RUNS_3_LO && runs[0][3] < FIPS_RUNS_3_HI &&
runs[0][4] > FIPS_RUNS_4_LO && runs[0][4] < FIPS_RUNS_4_HI &&
runs[0][5] > FIPS_RUNS_5_LO && runs[0][5] < FIPS_RUNS_5_HI &&
runs[0][6] > FIPS_RUNS_6_LO && runs[0][6] < FIPS_RUNS_6_HI &&
runs[1][1] > FIPS_RUNS_1_LO && runs[1][1] < FIPS_RUNS_1_HI &&
runs[1][2] > FIPS_RUNS_2_LO && runs[1][2] < FIPS_RUNS_2_HI &&
runs[1][3] > FIPS_RUNS_3_LO && runs[1][3] < FIPS_RUNS_3_HI &&
runs[1][4] > FIPS_RUNS_4_LO && runs[1][4] < FIPS_RUNS_4_HI &&
runs[1][5] > FIPS_RUNS_5_LO && runs[1][5] < FIPS_RUNS_5_HI &&
runs[1][6] > FIPS_RUNS_6_LO && runs[1][6] < FIPS_RUNS_6_HI);
The FIPS continuous output test
The FIPS continuous output test requires that random number generators (which
would include both entropy sources and PRNGs) have the data they are going to
produce broken up into “blocks” of at least 16 bytes. If the generator has a “natural”
block size of greater than 16 bytes, that should always get used. Otherwise,
any size 16 bytes or greater can be used. We recommend never using blocks larger
than 16 bytes (unless required) because the underlying generator uses larger blocks
naturally. *
This test collects the first block of output and never gives it to anyone. Instead, it is
compared against the second block of output and thrown away. The second block
may be output if it is not identical to the first block; otherwise, the system must fail.
* Usually, entropy sources do not have a natural block size that large, if they have one at all (there is usually a
somewhat artificial block size, such as the width of the memory you read to query the source).
Statistically Testing Random Numbers | 619
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