Add RAND_priv_bytes() for private keys
[openssl.git] / crypto / rand / drbg_lib.c
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 <string.h>
11 #include <openssl/crypto.h>
12 #include <openssl/err.h>
13 #include <openssl/rand.h>
14 #include "rand_lcl.h"
15
16 /*
17  * Support framework for NIST SP 800-90A DRBG, AES-CTR mode.
18  * The RAND_DRBG is OpenSSL's pointer to an instance of the DRBG.
19  *
20  * The OpenSSL model is to have new and free functions, and that new
21  * does all initialization.  That is not the NIST model, which has
22  * instantiation and un-instantiate, and re-use within a new/free
23  * lifecycle.  (No doubt this comes from the desire to support hardware
24  * DRBG, where allocation of resources on something like an HSM is
25  * a much bigger deal than just re-setting an allocated resource.)
26  */
27
28 /*
29  * Set/initialize |drbg| to be of type |nid|, with optional |flags|.
30  * Return -2 if the type is not supported, 1 on success and -1 on
31  * failure.
32  */
33 int RAND_DRBG_set(RAND_DRBG *drbg, int nid, unsigned int flags)
34 {
35     int ret = 1;
36
37     drbg->state = DRBG_UNINITIALISED;
38     drbg->flags = flags;
39     drbg->nid = nid;
40
41     switch (nid) {
42     default:
43         RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
44         return -2;
45     case 0:
46         /* Uninitialized; that's okay. */
47         return 1;
48     case NID_aes_128_ctr:
49     case NID_aes_192_ctr:
50     case NID_aes_256_ctr:
51         ret = ctr_init(drbg);
52         break;
53     }
54
55     if (ret < 0)
56         RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
57     return ret;
58 }
59
60 /*
61  * Allocate memory and initialize a new DRBG.  The |parent|, if not
62  * NULL, will be used to auto-seed this RAND_DRBG as needed.
63  */
64 RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
65 {
66     RAND_DRBG *drbg = OPENSSL_zalloc(sizeof(*drbg));
67     unsigned char *ucp = OPENSSL_zalloc(RANDOMNESS_NEEDED);
68
69     if (drbg == NULL || ucp == NULL) {
70         RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
71         goto err;
72     }
73     drbg->size = RANDOMNESS_NEEDED;
74     drbg->randomness = ucp;
75
76     drbg->parent = parent;
77     if (RAND_DRBG_set(drbg, type, flags) < 0)
78         goto err;
79
80     if (parent != NULL) {
81         if (parent->state == DRBG_UNINITIALISED
82                 && RAND_DRBG_instantiate(parent, NULL, 0) == 0)
83             goto err;
84         if (!RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_parent,
85                                      drbg_release_entropy,
86                                      NULL, NULL)
87                 /*
88                  * Add in our address.  Note we are adding the pointer
89                  * itself, not its contents!
90                  */
91                 || !RAND_DRBG_instantiate(drbg,
92                                           (unsigned char*)&drbg, sizeof(drbg)))
93             goto err;
94     }
95
96     return drbg;
97
98 err:
99     OPENSSL_free(ucp);
100     OPENSSL_free(drbg);
101     return NULL;
102 }
103
104 RAND_DRBG *RAND_DRBG_get0_global(void)
105 {
106     return &rand_drbg;
107 }
108
109 /*
110  * Uninstantiate |drbg| and free all memory.
111  */
112 void RAND_DRBG_free(RAND_DRBG *drbg)
113 {
114     /* The global DRBG is free'd by rand_cleanup_int() */
115     if (drbg == NULL || drbg == &rand_drbg)
116         return;
117
118     ctr_uninstantiate(drbg);
119     OPENSSL_cleanse(drbg->randomness, drbg->size);
120     OPENSSL_free(drbg->randomness);
121     CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
122     OPENSSL_clear_free(drbg, sizeof(*drbg));
123 }
124
125 /*
126  * Instantiate |drbg|, after it has been initialized.  Use |pers| and
127  * |perslen| as prediction-resistance input.
128  */
129 int RAND_DRBG_instantiate(RAND_DRBG *drbg,
130                           const unsigned char *pers, size_t perslen)
131 {
132     unsigned char *nonce = NULL, *entropy = NULL;
133     size_t noncelen = 0, entlen = 0;
134
135     if (perslen > drbg->max_pers) {
136         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
137                 RAND_R_PERSONALISATION_STRING_TOO_LONG);
138         goto end;
139     }
140     if (drbg->state != DRBG_UNINITIALISED) {
141         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
142                 drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
143                                           : RAND_R_ALREADY_INSTANTIATED);
144         goto end;
145     }
146
147     drbg->state = DRBG_ERROR;
148     if (drbg->get_entropy != NULL)
149         entlen = drbg->get_entropy(drbg, &entropy, drbg->strength,
150                                    drbg->min_entropy, drbg->max_entropy);
151     if (entlen < drbg->min_entropy || entlen > drbg->max_entropy) {
152         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
153         goto end;
154     }
155
156     if (drbg->max_nonce > 0 && drbg->get_nonce != NULL) {
157         noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
158                                    drbg->min_nonce, drbg->max_nonce);
159         if (noncelen < drbg->min_nonce || noncelen > drbg->max_nonce) {
160             RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_NONCE);
161             goto end;
162         }
163     }
164
165     if (!ctr_instantiate(drbg, entropy, entlen,
166                          nonce, noncelen, pers, perslen)) {
167         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
168         goto end;
169     }
170
171     drbg->state = DRBG_READY;
172     drbg->reseed_counter = 1;
173
174 end:
175     if (entropy != NULL && drbg->cleanup_entropy != NULL)
176         drbg->cleanup_entropy(drbg, entropy);
177     if (nonce != NULL && drbg->cleanup_nonce!= NULL )
178         drbg->cleanup_nonce(drbg, nonce);
179     if (drbg->state == DRBG_READY)
180         return 1;
181     return 0;
182 }
183
184 /*
185  * Uninstantiate |drbg|. Must be instantiated before it can be used.
186  */
187 int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
188 {
189     int ret = ctr_uninstantiate(drbg);
190
191     OPENSSL_cleanse(&drbg->ctr, sizeof(drbg->ctr));
192     drbg->state = DRBG_UNINITIALISED;
193     return ret;
194 }
195
196 /*
197  * Mix in the specified data to reseed |drbg|.
198  */
199 int RAND_DRBG_reseed(RAND_DRBG *drbg,
200                      const unsigned char *adin, size_t adinlen)
201 {
202     unsigned char *entropy = NULL;
203     size_t entlen = 0;
204
205     if (drbg->state == DRBG_ERROR) {
206         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
207         return 0;
208     }
209     if (drbg->state == DRBG_UNINITIALISED) {
210         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
211         return 0;
212     }
213
214     if (adin == NULL)
215         adinlen = 0;
216     else if (adinlen > drbg->max_adin) {
217         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
218         return 0;
219     }
220
221     drbg->state = DRBG_ERROR;
222     if (drbg->get_entropy != NULL)
223         entlen = drbg->get_entropy(drbg, &entropy, drbg->strength,
224                                    drbg->min_entropy, drbg->max_entropy);
225     if (entlen < drbg->min_entropy || entlen > drbg->max_entropy) {
226         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
227         goto end;
228     }
229
230     if (!ctr_reseed(drbg, entropy, entlen, adin, adinlen))
231         goto end;
232     drbg->state = DRBG_READY;
233     drbg->reseed_counter = 1;
234
235 end:
236     if (entropy != NULL && drbg->cleanup_entropy != NULL)
237         drbg->cleanup_entropy(drbg, entropy);
238     if (drbg->state == DRBG_READY)
239         return 1;
240     return 0;
241 }
242
243 /*
244  * Generate |outlen| bytes into the buffer at |out|.  Reseed if we need
245  * to or if |prediction_resistance| is set.  Additional input can be
246  * sent in |adin| and |adinlen|.
247  */
248 int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
249                        int prediction_resistance,
250                        const unsigned char *adin, size_t adinlen)
251 {
252     if (drbg->state == DRBG_ERROR) {
253         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
254         return 0;
255     }
256     if (drbg->state == DRBG_UNINITIALISED) {
257         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
258         return 0;
259     }
260     if (outlen > drbg->max_request) {
261         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
262         return 0;
263     }
264     if (adinlen > drbg->max_adin) {
265         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
266         return 0;
267     }
268
269     if (drbg->reseed_counter >= drbg->reseed_interval)
270         drbg->state = DRBG_RESEED;
271
272     if (drbg->state == DRBG_RESEED || prediction_resistance) {
273         if (!RAND_DRBG_reseed(drbg, adin, adinlen)) {
274             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
275             return 0;
276         }
277         adin = NULL;
278         adinlen = 0;
279     }
280
281     if (!ctr_generate(drbg, out, outlen, adin, adinlen)) {
282         drbg->state = DRBG_ERROR;
283         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
284         return 0;
285     }
286
287     if (drbg->reseed_counter >= drbg->reseed_interval)
288         drbg->state = DRBG_RESEED;
289     else
290         drbg->reseed_counter++;
291     return 1;
292 }
293
294 /*
295  * Set the callbacks for entropy and nonce.  We currently don't use
296  * the nonce; that's mainly for the KATs
297  */
298 int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
299                             RAND_DRBG_get_entropy_fn cb_get_entropy,
300                             RAND_DRBG_cleanup_entropy_fn cb_cleanup_entropy,
301                             RAND_DRBG_get_nonce_fn cb_get_nonce,
302                             RAND_DRBG_cleanup_nonce_fn cb_cleanup_nonce)
303 {
304     if (drbg->state != DRBG_UNINITIALISED)
305         return 0;
306     drbg->get_entropy = cb_get_entropy;
307     drbg->cleanup_entropy = cb_cleanup_entropy;
308     drbg->get_nonce = cb_get_nonce;
309     drbg->cleanup_nonce = cb_cleanup_nonce;
310     return 1;
311 }
312
313 /*
314  * Set the reseed interval.
315  */
316 int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, int interval)
317 {
318     if (interval < 0 || interval > MAX_RESEED)
319         return 0;
320     drbg->reseed_interval = interval;
321     return 1;
322 }
323
324 /*
325  * Get and set the EXDATA
326  */
327 int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
328 {
329     return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
330 }
331
332 void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
333 {
334     return CRYPTO_get_ex_data(&drbg->ex_data, idx);
335 }
336
337
338 /*
339  * The following functions provide a RAND_METHOD that works on the
340  * global DRBG.  They lock.
341  */
342
343 static int drbg_bytes(unsigned char *out, int count)
344 {
345     int ret = 0;
346     size_t chunk;
347
348     CRYPTO_THREAD_write_lock(rand_drbg.lock);
349     if (rand_drbg.state == DRBG_UNINITIALISED
350             && RAND_DRBG_instantiate(&rand_drbg, NULL, 0) == 0)
351         goto err;
352
353     for ( ; count > 0; count -= chunk, out += chunk) {
354         chunk = count;
355         if (chunk > rand_drbg.max_request)
356             chunk = rand_drbg.max_request;
357         ret = RAND_DRBG_generate(&rand_drbg, out, chunk, 0, NULL, 0);
358         if (!ret)
359             goto err;
360     }
361     ret = 1;
362
363 err:
364     CRYPTO_THREAD_unlock(rand_drbg.lock);
365     return ret;
366 }
367
368 static int drbg_add(const void *buf, int num, double randomness)
369 {
370     unsigned char *in = (unsigned char *)buf;
371     unsigned char *out, *end;
372
373     CRYPTO_THREAD_write_lock(rand_bytes.lock);
374     out = &rand_bytes.buff[rand_bytes.curr];
375     end = &rand_bytes.buff[rand_bytes.size];
376
377     /* Copy whatever fits into the end of the buffer. */
378     for ( ; --num >= 0 && out < end; rand_bytes.curr++)
379         *out++ = *in++;
380
381     /* XOR any the leftover. */
382     while (num > 0) {
383         for (out = rand_bytes.buff; --num >= 0 && out < end; )
384             *out++ ^= *in++;
385     }
386
387     CRYPTO_THREAD_unlock(rand_bytes.lock);
388     return 1;
389 }
390
391 static int drbg_seed(const void *buf, int num)
392 {
393     return drbg_add(buf, num, num);
394 }
395
396 static int drbg_status(void)
397 {
398     int ret;
399
400     CRYPTO_THREAD_write_lock(rand_drbg.lock);
401     ret = rand_drbg.state == DRBG_READY ? 1 : 0;
402     CRYPTO_THREAD_unlock(rand_drbg.lock);
403     return ret;
404 }
405
406 RAND_DRBG rand_drbg; /* The default global DRBG. */
407 RAND_DRBG priv_drbg; /* The global private-key DRBG. */
408
409 RAND_METHOD rand_meth = {
410     drbg_seed,
411     drbg_bytes,
412     NULL,
413     drbg_add,
414     drbg_bytes,
415     drbg_status
416 };
417
418 RAND_METHOD *RAND_OpenSSL(void)
419 {
420     return &rand_meth;
421 }