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Side by Side Diff: srtp/crypto/math/stat.c

Issue 2344973002: Update libsrtp to version 2.0 (Closed)
Patch Set: Add '.' back to include_dirs Created 4 years, 2 months ago
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1 /*
2 * stats.c
3 *
4 * statistical tests for randomness (FIPS 140-2, Section 4.9)
5 *
6 * David A. McGrew
7 * Cisco Systems, Inc.
8 */
9
10 /*
11 *
12 * Copyright (c) 2001-2006, Cisco Systems, Inc.
13 * All rights reserved.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 *
19 * Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 *
22 * Redistributions in binary form must reproduce the above
23 * copyright notice, this list of conditions and the following
24 * disclaimer in the documentation and/or other materials provided
25 * with the distribution.
26 *
27 * Neither the name of the Cisco Systems, Inc. nor the names of its
28 * contributors may be used to endorse or promote products derived
29 * from this software without specific prior written permission.
30 *
31 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
32 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
33 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
34 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
35 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
36 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
37 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
38 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
40 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
41 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
42 * OF THE POSSIBILITY OF SUCH DAMAGE.
43 *
44 */
45
46 #ifdef HAVE_CONFIG_H
47 #include <config.h>
48 #endif
49
50 #include "stat.h"
51
52 debug_module_t mod_stat = {
53 0, /* debugging is off by default */
54 (char *)"stat test" /* printable module name */
55 };
56
57 /*
58 * each test assumes that 20,000 bits (2500 octets) of data is
59 * provided as input
60 */
61
62 #define STAT_TEST_DATA_LEN 2500
63
64 err_status_t
65 stat_test_monobit(uint8_t *data) {
66 uint8_t *data_end = data + STAT_TEST_DATA_LEN;
67 uint16_t ones_count;
68
69 ones_count = 0;
70 while (data < data_end) {
71 ones_count += octet_get_weight(*data);
72 data++;
73 }
74
75 debug_print(mod_stat, "bit count: %d", ones_count);
76
77 if ((ones_count < 9725) || (ones_count > 10275))
78 return err_status_algo_fail;
79
80 return err_status_ok;
81 }
82
83 err_status_t
84 stat_test_poker(uint8_t *data) {
85 int i;
86 uint8_t *data_end = data + STAT_TEST_DATA_LEN;
87 double poker;
88 uint16_t f[16] = {
89 0, 0, 0, 0, 0, 0, 0, 0,
90 0, 0, 0, 0, 0, 0, 0, 0
91 };
92
93 while (data < data_end) {
94 f[*data & 0x0f]++; /* increment freq. count for low nibble */
95 f[(*data) >> 4]++; /* increment freq. count for high nibble */
96 data++;
97 }
98
99 poker = 0.0;
100 for (i=0; i < 16; i++)
101 poker += (double) f[i] * f[i];
102
103 poker *= (16.0 / 5000.0);
104 poker -= 5000.0;
105
106 debug_print(mod_stat, "poker test: %f\n", poker);
107
108 if ((poker < 2.16) || (poker > 46.17))
109 return err_status_algo_fail;
110
111 return err_status_ok;
112 }
113
114
115 /*
116 * runs[i] holds the number of runs of size (i-1)
117 */
118
119 err_status_t
120 stat_test_runs(uint8_t *data) {
121 uint8_t *data_end = data + STAT_TEST_DATA_LEN;
122 uint16_t runs[6] = { 0, 0, 0, 0, 0, 0 };
123 uint16_t gaps[6] = { 0, 0, 0, 0, 0, 0 };
124 uint16_t lo_value[6] = { 2315, 1114, 527, 240, 103, 103 };
125 uint16_t hi_value[6] = { 2685, 1386, 723, 384, 209, 209 };
126 int state = 0;
127 uint16_t mask;
128 int i;
129
130 /*
131 * the state variable holds the number of bits in the
132 * current run (or gap, if negative)
133 */
134
135 while (data < data_end) {
136
137 /* loop over the bits of this byte */
138 for (mask = 1; mask < 256; mask <<= 1) {
139 if (*data & mask) {
140
141 /* next bit is a one */
142 if (state > 0) {
143
144 /* prefix is a run, so increment the run-count */
145 state++;
146
147 /* check for long runs */
148 if (state > 25) {
149 debug_print(mod_stat, ">25 runs: %d", state);
150 return err_status_algo_fail;
151 }
152
153 } else if (state < 0) {
154
155 /* prefix is a gap */
156 if (state < -25) {
157 debug_print(mod_stat, ">25 gaps: %d", state);
158 return err_status_algo_fail; /* long-runs test failed */
159 }
160 if (state < -6) {
161 state = -6; /* group together gaps > 5 */
162 }
163 gaps[-1-state]++; /* increment gap count */
164 state = 1; /* set state at one set bit */
165 } else {
166
167 /* state is zero; this happens only at initialization */
168 state = 1;
169 }
170 } else {
171
172 /* next bit is a zero */
173 if (state > 0) {
174
175 /* prefix is a run */
176 if (state > 25) {
177 debug_print(mod_stat, ">25 runs (2): %d", state);
178 return err_status_algo_fail; /* long-runs test failed */
179 }
180 if (state > 6) {
181 state = 6; /* group together runs > 5 */
182 }
183 runs[state-1]++; /* increment run count */
184 state = -1; /* set state at one zero bit */
185 } else if (state < 0) {
186
187 /* prefix is a gap, so increment gap-count (decrement state) */
188 state--;
189
190 /* check for long gaps */
191 if (state < -25) {
192 debug_print(mod_stat, ">25 gaps (2): %d", state);
193 return err_status_algo_fail;
194 }
195
196 } else {
197
198 /* state is zero; this happens only at initialization */
199 state = -1;
200 }
201 }
202 }
203
204 /* move along to next octet */
205 data++;
206 }
207
208 if (mod_stat.on) {
209 debug_print(mod_stat, "runs test", NULL);
210 for (i=0; i < 6; i++)
211 debug_print(mod_stat, " runs[]: %d", runs[i]);
212 for (i=0; i < 6; i++)
213 debug_print(mod_stat, " gaps[]: %d", gaps[i]);
214 }
215
216 /* check run and gap counts against the fixed limits */
217 for (i=0; i < 6; i++)
218 if ( (runs[i] < lo_value[i] ) || (runs[i] > hi_value[i])
219 || (gaps[i] < lo_value[i] ) || (gaps[i] > hi_value[i]))
220 return err_status_algo_fail;
221
222
223 return err_status_ok;
224 }
225
226
227 /*
228 * the function stat_test_rand_source applys the FIPS-140-2 statistical
229 * tests to the random source defined by rs
230 *
231 */
232
233 #define RAND_SRC_BUF_OCTETS 50 /* this value MUST divide 2500! */
234
235 err_status_t
236 stat_test_rand_source(rand_source_func_t get_rand_bytes) {
237 int i;
238 double poker;
239 uint8_t *data, *data_end;
240 uint16_t f[16] = {
241 0, 0, 0, 0, 0, 0, 0, 0,
242 0, 0, 0, 0, 0, 0, 0, 0
243 };
244 uint8_t buffer[RAND_SRC_BUF_OCTETS];
245 err_status_t status;
246 int ones_count = 0;
247 uint16_t runs[6] = { 0, 0, 0, 0, 0, 0 };
248 uint16_t gaps[6] = { 0, 0, 0, 0, 0, 0 };
249 uint16_t lo_value[6] = { 2315, 1114, 527, 240, 103, 103 };
250 uint16_t hi_value[6] = { 2685, 1386, 723, 384, 209, 209 };
251 int state = 0;
252 uint16_t mask;
253
254 /* counters for monobit, poker, and runs tests are initialized above */
255
256 /* main loop: fill buffer, update counters for stat tests */
257 for (i=0; i < 2500; i+=RAND_SRC_BUF_OCTETS) {
258
259 /* fill data buffer */
260 status = get_rand_bytes(buffer, RAND_SRC_BUF_OCTETS);
261 if (status) {
262 debug_print(mod_stat, "couldn't get rand bytes: %d",status);
263 return status;
264 }
265
266 #if 0
267 debug_print(mod_stat, "%s",
268 octet_string_hex_string(buffer, RAND_SRC_BUF_OCTETS));
269 #endif
270
271 data = buffer;
272 data_end = data + RAND_SRC_BUF_OCTETS;
273 while (data < data_end) {
274
275 /* update monobit test counter */
276 ones_count += octet_get_weight(*data);
277
278 /* update poker test counters */
279 f[*data & 0x0f]++; /* increment freq. count for low nibble */
280 f[(*data) >> 4]++; /* increment freq. count for high nibble */
281
282 /* update runs test counters */
283 /* loop over the bits of this byte */
284 for (mask = 1; mask < 256; mask <<= 1) {
285 if (*data & mask) {
286
287 /* next bit is a one */
288 if (state > 0) {
289
290 /* prefix is a run, so increment the run-count */
291 state++;
292
293 /* check for long runs */
294 if (state > 25) {
295 debug_print(mod_stat, ">25 runs (3): %d", state);
296 return err_status_algo_fail;
297 }
298
299 } else if (state < 0) {
300
301 /* prefix is a gap */
302 if (state < -25) {
303 debug_print(mod_stat, ">25 gaps (3): %d", state);
304 return err_status_algo_fail; /* long-runs test failed */
305 }
306 if (state < -6) {
307 state = -6; /* group together gaps > 5 */
308 }
309 gaps[-1-state]++; /* increment gap count */
310 state = 1; /* set state at one set bit */
311 } else {
312
313 /* state is zero; this happens only at initialization */
314 state = 1;
315 }
316 } else {
317
318 /* next bit is a zero */
319 if (state > 0) {
320
321 /* prefix is a run */
322 if (state > 25) {
323 debug_print(mod_stat, ">25 runs (4): %d", state);
324 return err_status_algo_fail; /* long-runs test failed */
325 }
326 if (state > 6) {
327 state = 6; /* group together runs > 5 */
328 }
329 runs[state-1]++; /* increment run count */
330 state = -1; /* set state at one zero bit */
331 } else if (state < 0) {
332
333 /* prefix is a gap, so increment gap-count (decrement state) */
334 state--;
335
336 /* check for long gaps */
337 if (state < -25) {
338 debug_print(mod_stat, ">25 gaps (4): %d", state);
339 return err_status_algo_fail;
340 }
341
342 } else {
343
344 /* state is zero; this happens only at initialization */
345 state = -1;
346 }
347 }
348 }
349
350 /* advance data pointer */
351 data++;
352 }
353 }
354
355 /* check to see if test data is within bounds */
356
357 /* check monobit test data */
358
359 debug_print(mod_stat, "stat: bit count: %d", ones_count);
360
361 if ((ones_count < 9725) || (ones_count > 10275)) {
362 debug_print(mod_stat, "stat: failed monobit test %d", ones_count);
363 return err_status_algo_fail;
364 }
365
366 /* check poker test data */
367 poker = 0.0;
368 for (i=0; i < 16; i++)
369 poker += (double) f[i] * f[i];
370
371 poker *= (16.0 / 5000.0);
372 poker -= 5000.0;
373
374 debug_print(mod_stat, "stat: poker test: %f", poker);
375
376 if ((poker < 2.16) || (poker > 46.17)) {
377 debug_print(mod_stat, "stat: failed poker test", NULL);
378 return err_status_algo_fail;
379 }
380
381 /* check run and gap counts against the fixed limits */
382 for (i=0; i < 6; i++)
383 if ((runs[i] < lo_value[i] ) || (runs[i] > hi_value[i])
384 || (gaps[i] < lo_value[i] ) || (gaps[i] > hi_value[i])) {
385 debug_print(mod_stat, "stat: failed run/gap test", NULL);
386 return err_status_algo_fail;
387 }
388
389 debug_print(mod_stat, "passed random stat test", NULL);
390 return err_status_ok;
391 }
392
393 err_status_t
394 stat_test_rand_source_with_repetition(rand_source_func_t source, unsigned num_tr ials) {
395 unsigned int i;
396 err_status_t err = err_status_algo_fail;
397
398 for (i=0; i < num_trials; i++) {
399 err = stat_test_rand_source(source);
400 if (err == err_status_ok) {
401 return err_status_ok;
402 }
403 debug_print(mod_stat, "failed stat test (try number %d)\n", i);
404 }
405
406 return err;
407 }
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