| /* |
| * stats.c |
| * |
| * statistical tests |
| * |
| * David A. McGrew |
| * Cisco Systems, Inc. |
| */ |
| |
| /* |
| * |
| * Copyright (c) 2001-2006, Cisco Systems, Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer in the documentation and/or other materials provided |
| * with the distribution. |
| * |
| * Neither the name of the Cisco Systems, Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived |
| * from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, |
| * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
| * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| * OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| */ |
| |
| #ifdef HAVE_CONFIG_H |
| #include <config.h> |
| #endif |
| |
| #include "stat.h" |
| |
| srtp_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 |
| |
| srtp_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 srtp_err_status_algo_fail; |
| |
| return srtp_err_status_ok; |
| } |
| |
| srtp_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 srtp_err_status_algo_fail; |
| |
| return srtp_err_status_ok; |
| } |
| |
| |
| /* |
| * runs[i] holds the number of runs of size (i-1) |
| */ |
| |
| srtp_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 srtp_err_status_algo_fail; |
| } |
| |
| } else if (state < 0) { |
| |
| /* prefix is a gap */ |
| if (state < -25) { |
| debug_print(mod_stat, ">25 gaps: %d", state); |
| return srtp_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 srtp_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 srtp_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 srtp_err_status_algo_fail; |
| |
| |
| return srtp_err_status_ok; |
| } |
| |
| |