xref: /openbsd-src/lib/libcrypto/ec/ec_key.c (revision 1ad61ae0a79a724d2d3ec69e69c8e1d1ff6b53a0) 
1 /* $OpenBSD: ec_key.c,v 1.37 2023/08/03 18:53:56 tb Exp $ */
2 /*
3  * Written by Nils Larsch for the OpenSSL project.
4  */
5 /* ====================================================================
6  * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  *
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  *
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in
17  *    the documentation and/or other materials provided with the
18  *    distribution.
19  *
20  * 3. All advertising materials mentioning features or use of this
21  *    software must display the following acknowledgment:
22  *    "This product includes software developed by the OpenSSL Project
23  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
24  *
25  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26  *    endorse or promote products derived from this software without
27  *    prior written permission. For written permission, please contact
28  *    openssl-core@openssl.org.
29  *
30  * 5. Products derived from this software may not be called "OpenSSL"
31  *    nor may "OpenSSL" appear in their names without prior written
32  *    permission of the OpenSSL Project.
33  *
34  * 6. Redistributions of any form whatsoever must retain the following
35  *    acknowledgment:
36  *    "This product includes software developed by the OpenSSL Project
37  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
38  *
39  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
43  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50  * OF THE POSSIBILITY OF SUCH DAMAGE.
51  * ====================================================================
52  *
53  * This product includes cryptographic software written by Eric Young
54  * (eay@cryptsoft.com).  This product includes software written by Tim
55  * Hudson (tjh@cryptsoft.com).
56  *
57  */
58 /* ====================================================================
59  * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
60  * Portions originally developed by SUN MICROSYSTEMS, INC., and
61  * contributed to the OpenSSL project.
62  */
63 
64 #include <string.h>
65 
66 #include <openssl/opensslconf.h>
67 
68 #ifndef OPENSSL_NO_ENGINE
69 #include <openssl/engine.h>
70 #endif
71 #include <openssl/err.h>
72 
73 #include "bn_local.h"
74 #include "ec_local.h"
75 
76 EC_KEY *
77 EC_KEY_new(void)
78 {
79 	return EC_KEY_new_method(NULL);
80 }
81 LCRYPTO_ALIAS(EC_KEY_new);
82 
83 EC_KEY *
84 EC_KEY_new_by_curve_name(int nid)
85 {
86 	EC_KEY *ret = EC_KEY_new();
87 	if (ret == NULL)
88 		return NULL;
89 	ret->group = EC_GROUP_new_by_curve_name(nid);
90 	if (ret->group == NULL) {
91 		EC_KEY_free(ret);
92 		return NULL;
93 	}
94 	if (ret->meth->set_group != NULL &&
95 	    ret->meth->set_group(ret, ret->group) == 0) {
96 		EC_KEY_free(ret);
97 		return NULL;
98 	}
99 	return ret;
100 }
101 LCRYPTO_ALIAS(EC_KEY_new_by_curve_name);
102 
103 void
104 EC_KEY_free(EC_KEY *r)
105 {
106 	int i;
107 
108 	if (r == NULL)
109 		return;
110 
111 	i = CRYPTO_add(&r->references, -1, CRYPTO_LOCK_EC);
112 	if (i > 0)
113 		return;
114 
115 	if (r->meth != NULL && r->meth->finish != NULL)
116 		r->meth->finish(r);
117 
118 #ifndef OPENSSL_NO_ENGINE
119 	ENGINE_finish(r->engine);
120 #endif
121 	CRYPTO_free_ex_data(CRYPTO_EX_INDEX_EC_KEY, r, &r->ex_data);
122 
123 	EC_GROUP_free(r->group);
124 	EC_POINT_free(r->pub_key);
125 	BN_free(r->priv_key);
126 
127 	freezero(r, sizeof(EC_KEY));
128 }
129 LCRYPTO_ALIAS(EC_KEY_free);
130 
131 EC_KEY *
132 EC_KEY_copy(EC_KEY *dest, const EC_KEY *src)
133 {
134 	if (dest == NULL || src == NULL) {
135 		ECerror(ERR_R_PASSED_NULL_PARAMETER);
136 		return NULL;
137 	}
138 	if (src->meth != dest->meth) {
139 		if (dest->meth != NULL && dest->meth->finish != NULL)
140 			dest->meth->finish(dest);
141 #ifndef OPENSSL_NO_ENGINE
142 		if (ENGINE_finish(dest->engine) == 0)
143 			return 0;
144 		dest->engine = NULL;
145 #endif
146 	}
147 	/* copy the parameters */
148 	if (src->group) {
149 		const EC_METHOD *meth = EC_GROUP_method_of(src->group);
150 		/* clear the old group */
151 		EC_GROUP_free(dest->group);
152 		dest->group = EC_GROUP_new(meth);
153 		if (dest->group == NULL)
154 			return NULL;
155 		if (!EC_GROUP_copy(dest->group, src->group))
156 			return NULL;
157 	}
158 	/* copy the public key */
159 	if (src->pub_key && src->group) {
160 		EC_POINT_free(dest->pub_key);
161 		dest->pub_key = EC_POINT_new(src->group);
162 		if (dest->pub_key == NULL)
163 			return NULL;
164 		if (!EC_POINT_copy(dest->pub_key, src->pub_key))
165 			return NULL;
166 	}
167 	/* copy the private key */
168 	if (src->priv_key) {
169 		if (dest->priv_key == NULL) {
170 			dest->priv_key = BN_new();
171 			if (dest->priv_key == NULL)
172 				return NULL;
173 		}
174 		if (!bn_copy(dest->priv_key, src->priv_key))
175 			return NULL;
176 	}
177 
178 	/* copy the rest */
179 	dest->enc_flag = src->enc_flag;
180 	dest->conv_form = src->conv_form;
181 	dest->version = src->version;
182 	dest->flags = src->flags;
183 
184 	if (!CRYPTO_dup_ex_data(CRYPTO_EX_INDEX_EC_KEY, &dest->ex_data,
185 	    &((EC_KEY *)src)->ex_data))	/* XXX const */
186 		return NULL;
187 
188 	if (src->meth != dest->meth) {
189 #ifndef OPENSSL_NO_ENGINE
190 		if (src->engine != NULL && ENGINE_init(src->engine) == 0)
191 			return 0;
192 		dest->engine = src->engine;
193 #endif
194 		dest->meth = src->meth;
195 	}
196 
197 	if (src->meth != NULL && src->meth->copy != NULL &&
198 	    src->meth->copy(dest, src) == 0)
199 		return 0;
200 
201 	return dest;
202 }
203 LCRYPTO_ALIAS(EC_KEY_copy);
204 
205 EC_KEY *
206 EC_KEY_dup(const EC_KEY *ec_key)
207 {
208 	EC_KEY *ret;
209 
210 	if ((ret = EC_KEY_new_method(ec_key->engine)) == NULL)
211 		return NULL;
212 	if (EC_KEY_copy(ret, ec_key) == NULL) {
213 		EC_KEY_free(ret);
214 		return NULL;
215 	}
216 	return ret;
217 }
218 LCRYPTO_ALIAS(EC_KEY_dup);
219 
220 int
221 EC_KEY_up_ref(EC_KEY *r)
222 {
223 	int i = CRYPTO_add(&r->references, 1, CRYPTO_LOCK_EC);
224 	return ((i > 1) ? 1 : 0);
225 }
226 LCRYPTO_ALIAS(EC_KEY_up_ref);
227 
228 int
229 EC_KEY_set_ex_data(EC_KEY *r, int idx, void *arg)
230 {
231 	return CRYPTO_set_ex_data(&r->ex_data, idx, arg);
232 }
233 LCRYPTO_ALIAS(EC_KEY_set_ex_data);
234 
235 void *
236 EC_KEY_get_ex_data(const EC_KEY *r, int idx)
237 {
238 	return CRYPTO_get_ex_data(&r->ex_data, idx);
239 }
240 LCRYPTO_ALIAS(EC_KEY_get_ex_data);
241 
242 int
243 EC_KEY_generate_key(EC_KEY *eckey)
244 {
245 	if (eckey->meth->keygen != NULL)
246 		return eckey->meth->keygen(eckey);
247 	ECerror(EC_R_NOT_IMPLEMENTED);
248 	return 0;
249 }
250 LCRYPTO_ALIAS(EC_KEY_generate_key);
251 
252 int
253 ec_key_gen(EC_KEY *eckey)
254 {
255 	BIGNUM *priv_key = NULL;
256 	EC_POINT *pub_key = NULL;
257 	const BIGNUM *order;
258 	int ret = 0;
259 
260 	if (eckey == NULL || eckey->group == NULL) {
261 		ECerror(ERR_R_PASSED_NULL_PARAMETER);
262 		goto err;
263 	}
264 
265 	if ((priv_key = BN_new()) == NULL)
266 		goto err;
267 	if ((pub_key = EC_POINT_new(eckey->group)) == NULL)
268 		goto err;
269 
270 	if ((order = EC_GROUP_get0_order(eckey->group)) == NULL)
271 		goto err;
272 	if (!bn_rand_interval(priv_key, 1, order))
273 		goto err;
274 	if (!EC_POINT_mul(eckey->group, pub_key, priv_key, NULL, NULL, NULL))
275 		goto err;
276 
277 	BN_free(eckey->priv_key);
278 	eckey->priv_key = priv_key;
279 	priv_key = NULL;
280 
281 	EC_POINT_free(eckey->pub_key);
282 	eckey->pub_key = pub_key;
283 	pub_key = NULL;
284 
285 	ret = 1;
286 
287  err:
288 	EC_POINT_free(pub_key);
289 	BN_free(priv_key);
290 
291 	return ret;
292 }
293 
294 int
295 EC_KEY_check_key(const EC_KEY *eckey)
296 {
297 	BN_CTX *ctx = NULL;
298 	EC_POINT *point = NULL;
299 	const BIGNUM *order;
300 	int ret = 0;
301 
302 	if (eckey == NULL || eckey->group == NULL || eckey->pub_key == NULL) {
303 		ECerror(ERR_R_PASSED_NULL_PARAMETER);
304 		goto err;
305 	}
306 
307 	if (EC_POINT_is_at_infinity(eckey->group, eckey->pub_key) > 0) {
308 		ECerror(EC_R_POINT_AT_INFINITY);
309 		goto err;
310 	}
311 
312 	if ((ctx = BN_CTX_new()) == NULL)
313 		goto err;
314 
315 	if ((point = EC_POINT_new(eckey->group)) == NULL)
316 		goto err;
317 
318 	/* Ensure public key is on the elliptic curve. */
319 	if (EC_POINT_is_on_curve(eckey->group, eckey->pub_key, ctx) <= 0) {
320 		ECerror(EC_R_POINT_IS_NOT_ON_CURVE);
321 		goto err;
322 	}
323 
324 	/* Ensure public key multiplied by the order is the point at infinity. */
325 	if ((order = EC_GROUP_get0_order(eckey->group)) == NULL) {
326 		ECerror(EC_R_INVALID_GROUP_ORDER);
327 		goto err;
328 	}
329 	if (!EC_POINT_mul(eckey->group, point, NULL, eckey->pub_key, order, ctx)) {
330 		ECerror(ERR_R_EC_LIB);
331 		goto err;
332 	}
333 	if (EC_POINT_is_at_infinity(eckey->group, point) <= 0) {
334 		ECerror(EC_R_WRONG_ORDER);
335 		goto err;
336 	}
337 
338 	/*
339 	 * If the private key is present, ensure that the private key multiplied
340 	 * by the generator matches the public key.
341 	 */
342 	if (eckey->priv_key != NULL) {
343 		if (BN_cmp(eckey->priv_key, order) >= 0) {
344 			ECerror(EC_R_WRONG_ORDER);
345 			goto err;
346 		}
347 		if (!EC_POINT_mul(eckey->group, point, eckey->priv_key, NULL,
348 		    NULL, ctx)) {
349 			ECerror(ERR_R_EC_LIB);
350 			goto err;
351 		}
352 		if (EC_POINT_cmp(eckey->group, point, eckey->pub_key,
353 		    ctx) != 0) {
354 			ECerror(EC_R_INVALID_PRIVATE_KEY);
355 			goto err;
356 		}
357 	}
358 
359 	ret = 1;
360 
361  err:
362 	BN_CTX_free(ctx);
363 	EC_POINT_free(point);
364 
365 	return ret;
366 }
367 LCRYPTO_ALIAS(EC_KEY_check_key);
368 
369 int
370 EC_KEY_set_public_key_affine_coordinates(EC_KEY *key, BIGNUM *x, BIGNUM *y)
371 {
372 	BN_CTX *ctx = NULL;
373 	EC_POINT *point = NULL;
374 	BIGNUM *tx, *ty;
375 	int ret = 0;
376 
377 	if (key == NULL || key->group == NULL || x == NULL || y == NULL) {
378 		ECerror(ERR_R_PASSED_NULL_PARAMETER);
379 		goto err;
380 	}
381 
382 	if ((ctx = BN_CTX_new()) == NULL)
383 		goto err;
384 
385 	BN_CTX_start(ctx);
386 
387 	if ((tx = BN_CTX_get(ctx)) == NULL)
388 		goto err;
389 	if ((ty = BN_CTX_get(ctx)) == NULL)
390 		goto err;
391 
392 	if ((point = EC_POINT_new(key->group)) == NULL)
393 		goto err;
394 
395 	if (!EC_POINT_set_affine_coordinates(key->group, point, x, y, ctx))
396 		goto err;
397 	if (!EC_POINT_get_affine_coordinates(key->group, point, tx, ty, ctx))
398 		goto err;
399 
400 	/*
401 	 * Check if retrieved coordinates match originals: if not values are
402 	 * out of range.
403 	 */
404 	if (BN_cmp(x, tx) != 0 || BN_cmp(y, ty) != 0) {
405 		ECerror(EC_R_COORDINATES_OUT_OF_RANGE);
406 		goto err;
407 	}
408 	if (!EC_KEY_set_public_key(key, point))
409 		goto err;
410 	if (EC_KEY_check_key(key) == 0)
411 		goto err;
412 
413 	ret = 1;
414 
415  err:
416 	BN_CTX_end(ctx);
417 	BN_CTX_free(ctx);
418 	EC_POINT_free(point);
419 
420 	return ret;
421 }
422 LCRYPTO_ALIAS(EC_KEY_set_public_key_affine_coordinates);
423 
424 const EC_GROUP *
425 EC_KEY_get0_group(const EC_KEY *key)
426 {
427 	return key->group;
428 }
429 LCRYPTO_ALIAS(EC_KEY_get0_group);
430 
431 int
432 EC_KEY_set_group(EC_KEY *key, const EC_GROUP *group)
433 {
434 	if (key->meth->set_group != NULL &&
435 	    key->meth->set_group(key, group) == 0)
436 		return 0;
437 	EC_GROUP_free(key->group);
438 	key->group = EC_GROUP_dup(group);
439 	return (key->group == NULL) ? 0 : 1;
440 }
441 LCRYPTO_ALIAS(EC_KEY_set_group);
442 
443 const BIGNUM *
444 EC_KEY_get0_private_key(const EC_KEY *key)
445 {
446 	return key->priv_key;
447 }
448 LCRYPTO_ALIAS(EC_KEY_get0_private_key);
449 
450 int
451 EC_KEY_set_private_key(EC_KEY *key, const BIGNUM *priv_key)
452 {
453 	if (key->meth->set_private != NULL &&
454 	    key->meth->set_private(key, priv_key) == 0)
455 		return 0;
456 
457 	BN_free(key->priv_key);
458 	if ((key->priv_key = BN_dup(priv_key)) == NULL)
459 		return 0;
460 
461 	return 1;
462 }
463 LCRYPTO_ALIAS(EC_KEY_set_private_key);
464 
465 const EC_POINT *
466 EC_KEY_get0_public_key(const EC_KEY *key)
467 {
468 	return key->pub_key;
469 }
470 LCRYPTO_ALIAS(EC_KEY_get0_public_key);
471 
472 int
473 EC_KEY_set_public_key(EC_KEY *key, const EC_POINT *pub_key)
474 {
475 	if (key->meth->set_public != NULL &&
476 	    key->meth->set_public(key, pub_key) == 0)
477 		return 0;
478 
479 	EC_POINT_free(key->pub_key);
480 	if ((key->pub_key = EC_POINT_dup(pub_key, key->group)) == NULL)
481 		return 0;
482 
483 	return 1;
484 }
485 LCRYPTO_ALIAS(EC_KEY_set_public_key);
486 
487 unsigned int
488 EC_KEY_get_enc_flags(const EC_KEY *key)
489 {
490 	return key->enc_flag;
491 }
492 LCRYPTO_ALIAS(EC_KEY_get_enc_flags);
493 
494 void
495 EC_KEY_set_enc_flags(EC_KEY *key, unsigned int flags)
496 {
497 	key->enc_flag = flags;
498 }
499 LCRYPTO_ALIAS(EC_KEY_set_enc_flags);
500 
501 point_conversion_form_t
502 EC_KEY_get_conv_form(const EC_KEY *key)
503 {
504 	return key->conv_form;
505 }
506 LCRYPTO_ALIAS(EC_KEY_get_conv_form);
507 
508 void
509 EC_KEY_set_conv_form(EC_KEY *key, point_conversion_form_t cform)
510 {
511 	key->conv_form = cform;
512 	if (key->group != NULL)
513 		EC_GROUP_set_point_conversion_form(key->group, cform);
514 }
515 LCRYPTO_ALIAS(EC_KEY_set_conv_form);
516 
517 void
518 EC_KEY_set_asn1_flag(EC_KEY *key, int flag)
519 {
520 	if (key->group != NULL)
521 		EC_GROUP_set_asn1_flag(key->group, flag);
522 }
523 LCRYPTO_ALIAS(EC_KEY_set_asn1_flag);
524 
525 int
526 EC_KEY_precompute_mult(EC_KEY *key, BN_CTX *ctx)
527 {
528 	if (key->group == NULL)
529 		return 0;
530 	return EC_GROUP_precompute_mult(key->group, ctx);
531 }
532 LCRYPTO_ALIAS(EC_KEY_precompute_mult);
533 
534 int
535 EC_KEY_get_flags(const EC_KEY *key)
536 {
537 	return key->flags;
538 }
539 LCRYPTO_ALIAS(EC_KEY_get_flags);
540 
541 void
542 EC_KEY_set_flags(EC_KEY *key, int flags)
543 {
544 	key->flags |= flags;
545 }
546 LCRYPTO_ALIAS(EC_KEY_set_flags);
547 
548 void
549 EC_KEY_clear_flags(EC_KEY *key, int flags)
550 {
551 	key->flags &= ~flags;
552 }
553 LCRYPTO_ALIAS(EC_KEY_clear_flags);
554