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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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