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1 | /* |
2 | * Copyright 2011-2017 The OpenSSL Project Authors. All Rights Reserved. | |
3 | * | |
4 | * Licensed under the OpenSSL license (the "License"). You may not use | |
5 | * this file except in compliance with the License. You can obtain a copy | |
6 | * in the file LICENSE in the source distribution or at | |
7 | * https://www.openssl.org/source/license.html | |
8 | */ | |
9 | ||
10 | #include <stdlib.h> | |
11 | #include <string.h> | |
12 | #include <openssl/crypto.h> | |
13 | #include <openssl/err.h> | |
14 | #include <openssl/rand.h> | |
15 | #include "rand_lcl.h" | |
16 | #include "internal/thread_once.h" | |
17 | ||
18 | /* | |
19 | * Mapping of NIST SP 800-90A DRBG to OpenSSL RAND_METHOD. | |
20 | */ | |
21 | ||
22 | ||
23 | /* | |
24 | * The default global DRBG and its auto-init/auto-cleanup. | |
25 | */ | |
26 | static DRBG_CTX ossl_drbg; | |
27 | ||
28 | static CRYPTO_ONCE ossl_drbg_init = CRYPTO_ONCE_STATIC_INIT; | |
29 | ||
30 | DEFINE_RUN_ONCE_STATIC(do_ossl_drbg_init) | |
31 | { | |
32 | ossl_drbg.lock = CRYPTO_THREAD_lock_new(); | |
33 | return ossl_drbg.lock != NULL; | |
34 | } | |
35 | ||
36 | void rand_drbg_cleanup(void) | |
37 | { | |
38 | CRYPTO_THREAD_lock_free(ossl_drbg.lock); | |
39 | } | |
40 | ||
41 | static void inc_128(DRBG_CTR_CTX *cctx) | |
42 | { | |
43 | int i; | |
44 | unsigned char c; | |
45 | unsigned char *p = &cctx->V[15]; | |
46 | ||
47 | for (i = 0; i < 16; i++, p--) { | |
48 | c = *p; | |
49 | c++; | |
50 | *p = c; | |
51 | if (c != 0) { | |
52 | /* If we didn't wrap around, we're done. */ | |
53 | break; | |
54 | } | |
55 | } | |
56 | } | |
57 | ||
58 | static void ctr_XOR(DRBG_CTR_CTX *cctx, const unsigned char *in, size_t inlen) | |
59 | { | |
60 | size_t i, n; | |
61 | ||
62 | if (in == NULL || inlen == 0) | |
63 | return; | |
64 | ||
65 | /* | |
66 | * Any zero padding will have no effect on the result as we | |
67 | * are XORing. So just process however much input we have. | |
68 | */ | |
69 | n = inlen < cctx->keylen ? inlen : cctx->keylen; | |
70 | for (i = 0; i < n; i++) | |
71 | cctx->K[i] ^= in[i]; | |
72 | if (inlen <= cctx->keylen) | |
73 | return; | |
74 | ||
75 | n = inlen - cctx->keylen; | |
76 | if (n > 16) { | |
77 | /* Should never happen */ | |
78 | n = 16; | |
79 | } | |
80 | for (i = 0; i < 16; i++) | |
81 | cctx->V[i] ^= in[i + cctx->keylen]; | |
82 | } | |
83 | ||
84 | /* | |
85 | * Process a complete block using BCC algorithm of SP 800-90A 10.3.3 | |
86 | */ | |
87 | static void ctr_BCC_block(DRBG_CTR_CTX *cctx, unsigned char *out, | |
88 | const unsigned char *in) | |
89 | { | |
90 | int i; | |
91 | ||
92 | for (i = 0; i < 16; i++) | |
93 | out[i] ^= in[i]; | |
94 | AES_encrypt(out, out, &cctx->df_ks); | |
95 | } | |
96 | ||
97 | ||
98 | /* | |
99 | * Handle several BCC operations for as much data as we need for K and X | |
100 | */ | |
101 | static void ctr_BCC_blocks(DRBG_CTR_CTX *cctx, const unsigned char *in) | |
102 | { | |
103 | ctr_BCC_block(cctx, cctx->KX, in); | |
104 | ctr_BCC_block(cctx, cctx->KX + 16, in); | |
105 | if (cctx->keylen != 16) | |
106 | ctr_BCC_block(cctx, cctx->KX + 32, in); | |
107 | } | |
108 | ||
109 | /* | |
110 | * Initialise BCC blocks: these have the value 0,1,2 in leftmost positions: | |
111 | * see 10.3.1 stage 7. | |
112 | */ | |
113 | static void ctr_BCC_init(DRBG_CTR_CTX *cctx) | |
114 | { | |
115 | memset(cctx->KX, 0, 48); | |
116 | memset(cctx->bltmp, 0, 16); | |
117 | ctr_BCC_block(cctx, cctx->KX, cctx->bltmp); | |
118 | cctx->bltmp[3] = 1; | |
119 | ctr_BCC_block(cctx, cctx->KX + 16, cctx->bltmp); | |
120 | if (cctx->keylen != 16) { | |
121 | cctx->bltmp[3] = 2; | |
122 | ctr_BCC_block(cctx, cctx->KX + 32, cctx->bltmp); | |
123 | } | |
124 | } | |
125 | ||
126 | /* | |
127 | * Process several blocks into BCC algorithm, some possibly partial | |
128 | */ | |
129 | static void ctr_BCC_update(DRBG_CTR_CTX *cctx, | |
130 | const unsigned char *in, size_t inlen) | |
131 | { | |
132 | if (in == NULL || inlen == 0) | |
133 | return; | |
134 | ||
135 | /* If we have partial block handle it first */ | |
136 | if (cctx->bltmp_pos) { | |
137 | size_t left = 16 - cctx->bltmp_pos; | |
138 | ||
139 | /* If we now have a complete block process it */ | |
140 | if (inlen >= left) { | |
141 | memcpy(cctx->bltmp + cctx->bltmp_pos, in, left); | |
142 | ctr_BCC_blocks(cctx, cctx->bltmp); | |
143 | cctx->bltmp_pos = 0; | |
144 | inlen -= left; | |
145 | in += left; | |
146 | } | |
147 | } | |
148 | ||
149 | /* Process zero or more complete blocks */ | |
150 | for (; inlen >= 16; in += 16, inlen -= 16) { | |
151 | ctr_BCC_blocks(cctx, in); | |
152 | } | |
153 | ||
154 | /* Copy any remaining partial block to the temporary buffer */ | |
155 | if (inlen > 0) { | |
156 | memcpy(cctx->bltmp + cctx->bltmp_pos, in, inlen); | |
157 | cctx->bltmp_pos += inlen; | |
158 | } | |
159 | } | |
160 | ||
161 | static void ctr_BCC_final(DRBG_CTR_CTX *cctx) | |
162 | { | |
163 | if (cctx->bltmp_pos) { | |
164 | memset(cctx->bltmp + cctx->bltmp_pos, 0, 16 - cctx->bltmp_pos); | |
165 | ctr_BCC_blocks(cctx, cctx->bltmp); | |
166 | } | |
167 | } | |
168 | ||
169 | static void ctr_df(DRBG_CTR_CTX *cctx, | |
170 | const unsigned char *in1, size_t in1len, | |
171 | const unsigned char *in2, size_t in2len, | |
172 | const unsigned char *in3, size_t in3len) | |
173 | { | |
174 | static unsigned char c80 = 0x80; | |
175 | size_t inlen; | |
176 | unsigned char *p = cctx->bltmp; | |
177 | ||
178 | ctr_BCC_init(cctx); | |
179 | if (in1 == NULL) | |
180 | in1len = 0; | |
181 | if (in2 == NULL) | |
182 | in2len = 0; | |
183 | if (in3 == NULL) | |
184 | in3len = 0; | |
185 | inlen = in1len + in2len + in3len; | |
186 | /* Initialise L||N in temporary block */ | |
187 | *p++ = (inlen >> 24) & 0xff; | |
188 | *p++ = (inlen >> 16) & 0xff; | |
189 | *p++ = (inlen >> 8) & 0xff; | |
190 | *p++ = inlen & 0xff; | |
191 | ||
192 | /* NB keylen is at most 32 bytes */ | |
193 | *p++ = 0; | |
194 | *p++ = 0; | |
195 | *p++ = 0; | |
196 | *p = (unsigned char)((cctx->keylen + 16) & 0xff); | |
197 | cctx->bltmp_pos = 8; | |
198 | ctr_BCC_update(cctx, in1, in1len); | |
199 | ctr_BCC_update(cctx, in2, in2len); | |
200 | ctr_BCC_update(cctx, in3, in3len); | |
201 | ctr_BCC_update(cctx, &c80, 1); | |
202 | ctr_BCC_final(cctx); | |
203 | /* Set up key K */ | |
204 | AES_set_encrypt_key(cctx->KX, cctx->keylen * 8, &cctx->df_kxks); | |
205 | /* X follows key K */ | |
206 | AES_encrypt(cctx->KX + cctx->keylen, cctx->KX, &cctx->df_kxks); | |
207 | AES_encrypt(cctx->KX, cctx->KX + 16, &cctx->df_kxks); | |
208 | if (cctx->keylen != 16) | |
209 | AES_encrypt(cctx->KX + 16, cctx->KX + 32, &cctx->df_kxks); | |
210 | } | |
211 | ||
212 | /* | |
213 | * NB the no-df Update in SP800-90A specifies a constant input length | |
214 | * of seedlen, however other uses of this algorithm pad the input with | |
215 | * zeroes if necessary and have up to two parameters XORed together, | |
216 | * handle both cases in this function instead. | |
217 | */ | |
218 | static void ctr_update(DRBG_CTX *dctx, | |
219 | const unsigned char *in1, size_t in1len, | |
220 | const unsigned char *in2, size_t in2len, | |
221 | const unsigned char *nonce, size_t noncelen) | |
222 | { | |
223 | DRBG_CTR_CTX *cctx = &dctx->ctr; | |
224 | ||
225 | /* ks is already setup for correct key */ | |
226 | inc_128(cctx); | |
227 | AES_encrypt(cctx->V, cctx->K, &cctx->ks); | |
228 | ||
229 | /* If keylen longer than 128 bits need extra encrypt */ | |
230 | if (cctx->keylen != 16) { | |
231 | inc_128(cctx); | |
232 | AES_encrypt(cctx->V, cctx->K + 16, &cctx->ks); | |
233 | } | |
234 | inc_128(cctx); | |
235 | AES_encrypt(cctx->V, cctx->V, &cctx->ks); | |
236 | ||
237 | /* If 192 bit key part of V is on end of K */ | |
238 | if (cctx->keylen == 24) { | |
239 | memcpy(cctx->V + 8, cctx->V, 8); | |
240 | memcpy(cctx->V, cctx->K + 24, 8); | |
241 | } | |
242 | ||
243 | if (dctx->flags & RAND_DRBG_FLAG_CTR_USE_DF) { | |
244 | /* If no input reuse existing derived value */ | |
245 | if (in1 != NULL || nonce != NULL || in2 != NULL) | |
246 | ctr_df(cctx, in1, in1len, nonce, noncelen, in2, in2len); | |
247 | /* If this a reuse input in1len != 0 */ | |
248 | if (in1len) | |
249 | ctr_XOR(cctx, cctx->KX, dctx->seedlen); | |
250 | } else { | |
251 | ctr_XOR(cctx, in1, in1len); | |
252 | ctr_XOR(cctx, in2, in2len); | |
253 | } | |
254 | ||
255 | AES_set_encrypt_key(cctx->K, dctx->strength, &cctx->ks); | |
256 | } | |
257 | ||
258 | int ctr_instantiate(DRBG_CTX *dctx, | |
259 | const unsigned char *ent, size_t entlen, | |
260 | const unsigned char *nonce, size_t noncelen, | |
261 | const unsigned char *pers, size_t perslen) | |
262 | { | |
263 | DRBG_CTR_CTX *cctx = &dctx->ctr; | |
264 | ||
265 | memset(cctx->K, 0, sizeof(cctx->K)); | |
266 | memset(cctx->V, 0, sizeof(cctx->V)); | |
267 | AES_set_encrypt_key(cctx->K, dctx->strength, &cctx->ks); | |
268 | ctr_update(dctx, ent, entlen, pers, perslen, nonce, noncelen); | |
269 | return 1; | |
270 | } | |
271 | ||
272 | int ctr_reseed(DRBG_CTX *dctx, | |
273 | const unsigned char *ent, size_t entlen, | |
274 | const unsigned char *adin, size_t adinlen) | |
275 | { | |
276 | ctr_update(dctx, ent, entlen, adin, adinlen, NULL, 0); | |
277 | return 1; | |
278 | } | |
279 | ||
280 | int ctr_generate(DRBG_CTX *dctx, | |
281 | unsigned char *out, size_t outlen, | |
282 | const unsigned char *adin, size_t adinlen) | |
283 | { | |
284 | DRBG_CTR_CTX *cctx = &dctx->ctr; | |
285 | ||
286 | if (adin != NULL && adinlen != 0) { | |
287 | ctr_update(dctx, adin, adinlen, NULL, 0, NULL, 0); | |
288 | /* This means we reuse derived value */ | |
289 | if (dctx->flags & RAND_DRBG_FLAG_CTR_USE_DF) { | |
290 | adin = NULL; | |
291 | adinlen = 1; | |
292 | } | |
293 | } else { | |
294 | adinlen = 0; | |
295 | } | |
296 | ||
297 | for ( ; ; ) { | |
298 | inc_128(cctx); | |
299 | if (outlen < 16) { | |
300 | /* Use K as temp space as it will be updated */ | |
301 | AES_encrypt(cctx->V, cctx->K, &cctx->ks); | |
302 | memcpy(out, cctx->K, outlen); | |
303 | break; | |
304 | } | |
305 | AES_encrypt(cctx->V, out, &cctx->ks); | |
306 | out += 16; | |
307 | outlen -= 16; | |
308 | if (outlen == 0) | |
309 | break; | |
310 | } | |
311 | ||
312 | ctr_update(dctx, adin, adinlen, NULL, 0, NULL, 0); | |
313 | return 1; | |
314 | } | |
315 | ||
316 | int ctr_uninstantiate(DRBG_CTX *dctx) | |
317 | { | |
318 | memset(&dctx->ctr, 0, sizeof(dctx->ctr)); | |
319 | return 1; | |
320 | } | |
321 | ||
322 | int ctr_init(DRBG_CTX *dctx) | |
323 | { | |
324 | DRBG_CTR_CTX *cctx = &dctx->ctr; | |
325 | size_t keylen; | |
326 | ||
327 | switch (dctx->nid) { | |
328 | default: | |
329 | /* This can't happen, but silence the compiler warning. */ | |
330 | return -1; | |
331 | case NID_aes_128_ctr: | |
332 | keylen = 16; | |
333 | break; | |
334 | case NID_aes_192_ctr: | |
335 | keylen = 24; | |
336 | break; | |
337 | case NID_aes_256_ctr: | |
338 | keylen = 32; | |
339 | break; | |
340 | } | |
341 | ||
342 | cctx->keylen = keylen; | |
343 | dctx->strength = keylen * 8; | |
344 | dctx->blocklength = 16; | |
345 | dctx->seedlen = keylen + 16; | |
346 | ||
347 | if (dctx->flags & RAND_DRBG_FLAG_CTR_USE_DF) { | |
348 | /* df initialisation */ | |
349 | static unsigned char df_key[32] = { | |
350 | 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07, | |
351 | 0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f, | |
352 | 0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17, | |
353 | 0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f | |
354 | }; | |
355 | /* Set key schedule for df_key */ | |
356 | AES_set_encrypt_key(df_key, dctx->strength, &cctx->df_ks); | |
357 | ||
358 | dctx->min_entropy = cctx->keylen; | |
359 | dctx->max_entropy = DRBG_MAX_LENGTH; | |
360 | dctx->min_nonce = dctx->min_entropy / 2; | |
361 | dctx->max_nonce = DRBG_MAX_LENGTH; | |
362 | dctx->max_pers = DRBG_MAX_LENGTH; | |
363 | dctx->max_adin = DRBG_MAX_LENGTH; | |
364 | } else { | |
365 | dctx->min_entropy = dctx->seedlen; | |
366 | dctx->max_entropy = dctx->seedlen; | |
367 | /* Nonce not used */ | |
368 | dctx->min_nonce = 0; | |
369 | dctx->max_nonce = 0; | |
370 | dctx->max_pers = dctx->seedlen; | |
371 | dctx->max_adin = dctx->seedlen; | |
372 | } | |
373 | ||
374 | dctx->max_request = 1 << 16; | |
375 | dctx->reseed_interval = 1 << 24; | |
376 | return 1; | |
377 | } | |
378 | ||
379 | ||
380 | /* | |
381 | * The following function tie the DRBG code into the RAND_METHOD | |
382 | */ | |
383 | ||
384 | DRBG_CTX *RAND_DRBG_get_default(void) | |
385 | { | |
386 | if (!RUN_ONCE(&ossl_drbg_init, do_ossl_drbg_init)) | |
387 | return NULL; | |
388 | return &ossl_drbg; | |
389 | } | |
390 | ||
391 | static int drbg_bytes(unsigned char *out, int count) | |
392 | { | |
393 | DRBG_CTX *dctx = RAND_DRBG_get_default(); | |
394 | int ret = 0; | |
395 | ||
396 | CRYPTO_THREAD_write_lock(dctx->lock); | |
397 | do { | |
398 | size_t rcnt; | |
399 | ||
400 | if (count > (int)dctx->max_request) | |
401 | rcnt = dctx->max_request; | |
402 | else | |
403 | rcnt = count; | |
404 | ret = RAND_DRBG_generate(dctx, out, rcnt, 0, NULL, 0); | |
405 | if (!ret) | |
406 | goto err; | |
407 | out += rcnt; | |
408 | count -= rcnt; | |
409 | } while (count); | |
410 | ret = 1; | |
411 | err: | |
412 | CRYPTO_THREAD_unlock(dctx->lock); | |
413 | return ret; | |
414 | } | |
415 | ||
416 | static int drbg_status(void) | |
417 | { | |
418 | DRBG_CTX *dctx = RAND_DRBG_get_default(); | |
419 | int ret; | |
420 | ||
421 | CRYPTO_THREAD_write_lock(dctx->lock); | |
422 | ret = dctx->status == DRBG_STATUS_READY ? 1 : 0; | |
423 | CRYPTO_THREAD_unlock(dctx->lock); | |
424 | return ret; | |
425 | } | |
426 | ||
427 | static void drbg_cleanup(void) | |
428 | { | |
429 | DRBG_CTX *dctx = RAND_DRBG_get_default(); | |
430 | ||
431 | CRYPTO_THREAD_write_lock(dctx->lock); | |
432 | RAND_DRBG_uninstantiate(dctx); | |
433 | CRYPTO_THREAD_unlock(dctx->lock); | |
434 | } | |
435 | ||
436 | static const RAND_METHOD rand_drbg_meth = | |
437 | { | |
438 | NULL, | |
439 | drbg_bytes, | |
440 | drbg_cleanup, | |
441 | NULL, | |
442 | drbg_bytes, | |
443 | drbg_status | |
444 | }; | |
445 | ||
446 | const RAND_METHOD *RAND_drbg(void) | |
447 | { | |
448 | return &rand_drbg_meth; | |
449 | } |