1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
|
/*
* stats.c
*
* statistical tests for randomness (FIPS 140-2, Section 4.9)
*
* David A. McGrew
* Cisco Systems, Inc.
*/
#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;
}
|
