| /* |
| * stats.c |
| * |
| * statistical tests for randomness (FIPS 140-2, Section 4.9) |
| * |
| * David A. McGrew |
| * Cisco Systems, Inc. |
| */ |
| |
| #ifdef HAVE_CONFIG_H |
| #include <config.h> |
| #endif |
| |
| #include "stat.h" |
| |
| debug_module_t mod_stat = { |
| 0, /* debugging is off by default */ |
| (char *)"stat test" /* printable module name */ |
| }; |
| |
| /* |
| * each test assumes that 20,000 bits (2500 octets) of data is |
| * provided as input |
| */ |
| |
| #define STAT_TEST_DATA_LEN 2500 |
| |
| err_status_t |
| stat_test_monobit(uint8_t *data) { |
| uint8_t *data_end = data + STAT_TEST_DATA_LEN; |
| uint16_t ones_count; |
| |
| ones_count = 0; |
| while (data < data_end) { |
| ones_count += octet_get_weight(*data); |
| data++; |
| } |
| |
| debug_print(mod_stat, "bit count: %d", ones_count); |
| |
| if ((ones_count < 9725) || (ones_count > 10275)) |
| return err_status_algo_fail; |
| |
| return err_status_ok; |
| } |
| |
| err_status_t |
| stat_test_poker(uint8_t *data) { |
| int i; |
| uint8_t *data_end = data + STAT_TEST_DATA_LEN; |
| double poker; |
| uint16_t f[16] = { |
| 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0 |
| }; |
| |
| while (data < data_end) { |
| f[*data & 0x0f]++; /* increment freq. count for low nibble */ |
| f[(*data) >> 4]++; /* increment freq. count for high nibble */ |
| data++; |
| } |
| |
| poker = 0.0; |
| for (i=0; i < 16; i++) |
| poker += (double) f[i] * f[i]; |
| |
| poker *= (16.0 / 5000.0); |
| poker -= 5000.0; |
| |
| debug_print(mod_stat, "poker test: %f\n", poker); |
| |
| if ((poker < 2.16) || (poker > 46.17)) |
| return err_status_algo_fail; |
| |
| return err_status_ok; |
| } |
| |
| |
| /* |
| * runs[i] holds the number of runs of size (i-1) |
| */ |
| |
| err_status_t |
| stat_test_runs(uint8_t *data) { |
| uint8_t *data_end = data + STAT_TEST_DATA_LEN; |
| uint16_t runs[6] = { 0, 0, 0, 0, 0, 0 }; |
| uint16_t gaps[6] = { 0, 0, 0, 0, 0, 0 }; |
| uint16_t lo_value[6] = { 2315, 1114, 527, 240, 103, 103 }; |
| uint16_t hi_value[6] = { 2685, 1386, 723, 384, 209, 209 }; |
| int state = 0; |
| uint16_t mask; |
| int i; |
| |
| /* |
| * the state variable holds the number of bits in the |
| * current run (or gap, if negative) |
| */ |
| |
| while (data < data_end) { |
| |
| /* loop over the bits of this byte */ |
| for (mask = 1; mask < 256; mask <<= 1) { |
| if (*data & mask) { |
| |
| /* next bit is a one */ |
| if (state > 0) { |
| |
| /* prefix is a run, so increment the run-count */ |
| state++; |
| |
| /* check for long runs */ |
| if (state > 25) { |
| debug_print(mod_stat, ">25 runs: %d", state); |
| return err_status_algo_fail; |
| } |
| |
| } else if (state < 0) { |
| |
| /* prefix is a gap */ |
| if (state < -25) { |
| debug_print(mod_stat, ">25 gaps: %d", state); |
| return err_status_algo_fail; /* long-runs test failed */ |
| } |
| if (state < -6) { |
| state = -6; /* group together gaps > 5 */ |
| } |
| gaps[-1-state]++; /* increment gap count */ |
| state = 1; /* set state at one set bit */ |
| } else { |
| |
| /* state is zero; this happens only at initialization */ |
| state = 1; |
| } |
| } else { |
| |
| /* next bit is a zero */ |
| if (state > 0) { |
| |
| /* prefix is a run */ |
| if (state > 25) { |
| debug_print(mod_stat, ">25 runs (2): %d", state); |
| return err_status_algo_fail; /* long-runs test failed */ |
| } |
| if (state > 6) { |
| state = 6; /* group together runs > 5 */ |
| } |
| runs[state-1]++; /* increment run count */ |
| state = -1; /* set state at one zero bit */ |
| } else if (state < 0) { |
| |
| /* prefix is a gap, so increment gap-count (decrement state) */ |
| state--; |
| |
| /* check for long gaps */ |
| if (state < -25) { |
| debug_print(mod_stat, ">25 gaps (2): %d", state); |
| return err_status_algo_fail; |
| } |
| |
| } else { |
| |
| /* state is zero; this happens only at initialization */ |
| state = -1; |
| } |
| } |
| } |
| |
| /* move along to next octet */ |
| data++; |
| } |
| |
| if (mod_stat.on) { |
| debug_print(mod_stat, "runs test", NULL); |
| for (i=0; i < 6; i++) |
| debug_print(mod_stat, " runs[]: %d", runs[i]); |
| for (i=0; i < 6; i++) |
| debug_print(mod_stat, " gaps[]: %d", gaps[i]); |
| } |
| |
| /* check run and gap counts against the fixed limits */ |
| for (i=0; i < 6; i++) |
| if ( (runs[i] < lo_value[i] ) || (runs[i] > hi_value[i]) |
| || (gaps[i] < lo_value[i] ) || (gaps[i] > hi_value[i])) |
| return err_status_algo_fail; |
| |
| |
| return err_status_ok; |
| } |
| |
| |
| /* |
| * the function stat_test_rand_source applys the FIPS-140-2 statistical |
| * tests to the random source defined by rs |
| * |
| */ |
| |
| #define RAND_SRC_BUF_OCTETS 50 /* this value MUST divide 2500! */ |
| |
| err_status_t |
| stat_test_rand_source(rand_source_func_t get_rand_bytes) { |
| int i; |
| double poker; |
| uint8_t *data, *data_end; |
| uint16_t f[16] = { |
| 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0 |
| }; |
| uint8_t buffer[RAND_SRC_BUF_OCTETS]; |
| err_status_t status; |
| int ones_count = 0; |
| uint16_t runs[6] = { 0, 0, 0, 0, 0, 0 }; |
| uint16_t gaps[6] = { 0, 0, 0, 0, 0, 0 }; |
| uint16_t lo_value[6] = { 2315, 1114, 527, 240, 103, 103 }; |
| uint16_t hi_value[6] = { 2685, 1386, 723, 384, 209, 209 }; |
| int state = 0; |
| uint16_t mask; |
| |
| /* counters for monobit, poker, and runs tests are initialized above */ |
| |
| /* main loop: fill buffer, update counters for stat tests */ |
| for (i=0; i < 2500; i+=RAND_SRC_BUF_OCTETS) { |
| |
| /* fill data buffer */ |
| status = get_rand_bytes(buffer, RAND_SRC_BUF_OCTETS); |
| if (status) { |
| debug_print(mod_stat, "couldn't get rand bytes: %d",status); |
| return status; |
| } |
| |
| #if 0 |
| debug_print(mod_stat, "%s", |
| octet_string_hex_string(buffer, RAND_SRC_BUF_OCTETS)); |
| #endif |
| |
| data = buffer; |
| data_end = data + RAND_SRC_BUF_OCTETS; |
| while (data < data_end) { |
| |
| /* update monobit test counter */ |
| ones_count += octet_get_weight(*data); |
| |
| /* update poker test counters */ |
| f[*data & 0x0f]++; /* increment freq. count for low nibble */ |
| f[(*data) >> 4]++; /* increment freq. count for high nibble */ |
| |
| /* update runs test counters */ |
| /* loop over the bits of this byte */ |
| for (mask = 1; mask < 256; mask <<= 1) { |
| if (*data & mask) { |
| |
| /* next bit is a one */ |
| if (state > 0) { |
| |
| /* prefix is a run, so increment the run-count */ |
| state++; |
| |
| /* check for long runs */ |
| if (state > 25) { |
| debug_print(mod_stat, ">25 runs (3): %d", state); |
| return err_status_algo_fail; |
| } |
| |
| } else if (state < 0) { |
| |
| /* prefix is a gap */ |
| if (state < -25) { |
| debug_print(mod_stat, ">25 gaps (3): %d", state); |
| return err_status_algo_fail; /* long-runs test failed */ |
| } |
| if (state < -6) { |
| state = -6; /* group together gaps > 5 */ |
| } |
| gaps[-1-state]++; /* increment gap count */ |
| state = 1; /* set state at one set bit */ |
| } else { |
| |
| /* state is zero; this happens only at initialization */ |
| state = 1; |
| } |
| } else { |
| |
| /* next bit is a zero */ |
| if (state > 0) { |
| |
| /* prefix is a run */ |
| if (state > 25) { |
| debug_print(mod_stat, ">25 runs (4): %d", state); |
| return err_status_algo_fail; /* long-runs test failed */ |
| } |
| if (state > 6) { |
| state = 6; /* group together runs > 5 */ |
| } |
| runs[state-1]++; /* increment run count */ |
| state = -1; /* set state at one zero bit */ |
| } else if (state < 0) { |
| |
| /* prefix is a gap, so increment gap-count (decrement state) */ |
| state--; |
| |
| /* check for long gaps */ |
| if (state < -25) { |
| debug_print(mod_stat, ">25 gaps (4): %d", state); |
| return err_status_algo_fail; |
| } |
| |
| } else { |
| |
| /* state is zero; this happens only at initialization */ |
| state = -1; |
| } |
| } |
| } |
| |
| /* advance data pointer */ |
| data++; |
| } |
| } |
| |
| /* check to see if test data is within bounds */ |
| |
| /* check monobit test data */ |
| |
| debug_print(mod_stat, "stat: bit count: %d", ones_count); |
| |
| if ((ones_count < 9725) || (ones_count > 10275)) { |
| debug_print(mod_stat, "stat: failed monobit test %d", ones_count); |
| return err_status_algo_fail; |
| } |
| |
| /* check poker test data */ |
| poker = 0.0; |
| for (i=0; i < 16; i++) |
| poker += (double) f[i] * f[i]; |
| |
| poker *= (16.0 / 5000.0); |
| poker -= 5000.0; |
| |
| debug_print(mod_stat, "stat: poker test: %f", poker); |
| |
| if ((poker < 2.16) || (poker > 46.17)) { |
| debug_print(mod_stat, "stat: failed poker test", NULL); |
| return err_status_algo_fail; |
| } |
| |
| /* check run and gap counts against the fixed limits */ |
| for (i=0; i < 6; i++) |
| if ((runs[i] < lo_value[i] ) || (runs[i] > hi_value[i]) |
| || (gaps[i] < lo_value[i] ) || (gaps[i] > hi_value[i])) { |
| debug_print(mod_stat, "stat: failed run/gap test", NULL); |
| return err_status_algo_fail; |
| } |
| |
| debug_print(mod_stat, "passed random stat test", NULL); |
| return err_status_ok; |
| } |
| |
| err_status_t |
| stat_test_rand_source_with_repetition(rand_source_func_t source, unsigned num_trials) { |
| unsigned int i; |
| err_status_t err = err_status_algo_fail; |
| |
| for (i=0; i < num_trials; i++) { |
| err = stat_test_rand_source(source); |
| if (err == err_status_ok) { |
| return err_status_ok; |
| } |
| debug_print(mod_stat, "failed stat test (try number %d)\n", i); |
| } |
| |
| return err; |
| } |