xref: /openbsd/lib/libcrypto/ec/ec_pmeth.c (revision 8c0ef552) 
1 /* $OpenBSD: ec_pmeth.c,v 1.24 2025/01/05 16:07:08 tb Exp $ */
2 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
3  * project 2006.
4  */
5 /* ====================================================================
6  * Copyright (c) 2006 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  *    licensing@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 #include <stdio.h>
60 #include <stdlib.h>
61 #include <string.h>
62 
63 #include <openssl/asn1t.h>
64 #include <openssl/ec.h>
65 #include <openssl/err.h>
66 #include <openssl/evp.h>
67 #include <openssl/x509.h>
68 
69 #include "bn_local.h"
70 #include "ec_local.h"
71 #include "evp_local.h"
72 
73 /* EC pkey context structure */
74 
75 typedef struct {
76 	/* Key and paramgen group */
77 	EC_GROUP *gen_group;
78 	/* message digest */
79 	const EVP_MD *md;
80 	/* Duplicate key if custom cofactor needed */
81 	EC_KEY *co_key;
82 	/* Cofactor mode */
83 	signed char cofactor_mode;
84 	/* KDF (if any) to use for ECDH */
85 	char kdf_type;
86 	/* Message digest to use for key derivation */
87 	const EVP_MD *kdf_md;
88 	/* User key material */
89 	unsigned char *kdf_ukm;
90 	size_t kdf_ukmlen;
91 	/* KDF output length */
92 	size_t kdf_outlen;
93 } EC_PKEY_CTX;
94 
95 static int
96 pkey_ec_init(EVP_PKEY_CTX *ctx)
97 {
98 	EC_PKEY_CTX *dctx;
99 
100 	if ((dctx = calloc(1, sizeof(EC_PKEY_CTX))) == NULL) {
101 		ECerror(ERR_R_MALLOC_FAILURE);
102 		return 0;
103 	}
104 
105 	dctx->cofactor_mode = -1;
106 	dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
107 
108 	ctx->data = dctx;
109 
110 	return 1;
111 }
112 
113 static int
114 pkey_ec_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
115 {
116 	EC_PKEY_CTX *dctx, *sctx;
117 	if (!pkey_ec_init(dst))
118 		return 0;
119 	sctx = src->data;
120 	dctx = dst->data;
121 	if (sctx->gen_group) {
122 		dctx->gen_group = EC_GROUP_dup(sctx->gen_group);
123 		if (!dctx->gen_group)
124 			return 0;
125 	}
126 	dctx->md = sctx->md;
127 
128 	if (sctx->co_key) {
129 		dctx->co_key = EC_KEY_dup(sctx->co_key);
130 		if (!dctx->co_key)
131 			return 0;
132 	}
133 	dctx->kdf_type = sctx->kdf_type;
134 	dctx->kdf_md = sctx->kdf_md;
135 	dctx->kdf_outlen = sctx->kdf_outlen;
136 	if (sctx->kdf_ukm) {
137 		if ((dctx->kdf_ukm = calloc(1, sctx->kdf_ukmlen)) == NULL)
138 			return 0;
139 		memcpy(dctx->kdf_ukm, sctx->kdf_ukm, sctx->kdf_ukmlen);
140 	} else
141 		dctx->kdf_ukm = NULL;
142 
143 	dctx->kdf_ukmlen = sctx->kdf_ukmlen;
144 
145 	return 1;
146 }
147 
148 static void
149 pkey_ec_cleanup(EVP_PKEY_CTX *ctx)
150 {
151 	EC_PKEY_CTX *dctx = ctx->data;
152 
153 	if (dctx != NULL) {
154 		EC_GROUP_free(dctx->gen_group);
155 		EC_KEY_free(dctx->co_key);
156 		free(dctx->kdf_ukm);
157 		free(dctx);
158 		ctx->data = NULL;
159 	}
160 }
161 
162 static int
163 pkey_ec_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
164     const unsigned char *tbs, size_t tbslen)
165 {
166 	int ret, type;
167 	unsigned int sltmp;
168 	EC_PKEY_CTX *dctx = ctx->data;
169 	EC_KEY *ec = ctx->pkey->pkey.ec;
170 
171 	if (!sig) {
172 		*siglen = ECDSA_size(ec);
173 		return 1;
174 	} else if (*siglen < (size_t) ECDSA_size(ec)) {
175 		ECerror(EC_R_BUFFER_TOO_SMALL);
176 		return 0;
177 	}
178 	if (dctx->md)
179 		type = EVP_MD_type(dctx->md);
180 	else
181 		type = NID_sha1;
182 
183 	ret = ECDSA_sign(type, tbs, tbslen, sig, &sltmp, ec);
184 	if (ret <= 0)
185 		return ret;
186 	*siglen = (size_t) sltmp;
187 	return 1;
188 }
189 
190 static int
191 pkey_ec_verify(EVP_PKEY_CTX *ctx,
192     const unsigned char *sig, size_t siglen,
193     const unsigned char *tbs, size_t tbslen)
194 {
195 	int ret, type;
196 	EC_PKEY_CTX *dctx = ctx->data;
197 	EC_KEY *ec = ctx->pkey->pkey.ec;
198 
199 	if (dctx->md)
200 		type = EVP_MD_type(dctx->md);
201 	else
202 		type = NID_sha1;
203 
204 	ret = ECDSA_verify(type, tbs, tbslen, sig, siglen, ec);
205 
206 	return ret;
207 }
208 
209 static int
210 pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
211 {
212 	int ret;
213 	size_t outlen;
214 	const EC_POINT *pubkey = NULL;
215 	EC_KEY *eckey;
216 	EC_PKEY_CTX *dctx = ctx->data;
217 
218 	if (!ctx->pkey || !ctx->peerkey) {
219 		ECerror(EC_R_KEYS_NOT_SET);
220 		return 0;
221 	}
222 
223 	eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
224 	if (!key) {
225 		const EC_GROUP *group;
226 		group = EC_KEY_get0_group(eckey);
227 		*keylen = (EC_GROUP_get_degree(group) + 7) / 8;
228 		return 1;
229 	}
230 	pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);
231 
232 	/*
233 	 * NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is
234 	 * not an error, the result is truncated.
235 	 */
236 
237 	outlen = *keylen;
238 
239 	ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
240 	if (ret <= 0)
241 		return 0;
242 
243 	*keylen = ret;
244 
245 	return 1;
246 }
247 
248 static int
249 pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
250 {
251 	EC_PKEY_CTX *dctx = ctx->data;
252 	unsigned char *ktmp = NULL;
253 	size_t ktmplen;
254 	int rv = 0;
255 
256 	if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
257 		return pkey_ec_derive(ctx, key, keylen);
258 
259 	if (!key) {
260 		*keylen = dctx->kdf_outlen;
261 		return 1;
262 	}
263 	if (*keylen != dctx->kdf_outlen)
264 		return 0;
265 	if (!pkey_ec_derive(ctx, NULL, &ktmplen))
266 		return 0;
267 	if ((ktmp = calloc(1, ktmplen)) == NULL) {
268 		ECerror(ERR_R_MALLOC_FAILURE);
269 		return 0;
270 	}
271 	if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
272 		goto err;
273 	/* Do KDF stuff */
274 	if (!ecdh_KDF_X9_63(key, *keylen, ktmp, ktmplen, dctx->kdf_ukm,
275 	    dctx->kdf_ukmlen, dctx->kdf_md))
276 		goto err;
277 	rv = 1;
278 
279  err:
280 	freezero(ktmp, ktmplen);
281 
282 	return rv;
283 }
284 
285 static int
286 pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
287 {
288 	EC_PKEY_CTX *dctx = ctx->data;
289 	EC_GROUP *group;
290 
291 	switch (type) {
292 	case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
293 		group = EC_GROUP_new_by_curve_name(p1);
294 		if (group == NULL) {
295 			ECerror(EC_R_INVALID_CURVE);
296 			return 0;
297 		}
298 		EC_GROUP_free(dctx->gen_group);
299 		dctx->gen_group = group;
300 		return 1;
301 
302 	case EVP_PKEY_CTRL_EC_PARAM_ENC:
303 		if (!dctx->gen_group) {
304 			ECerror(EC_R_NO_PARAMETERS_SET);
305 			return 0;
306 		}
307 		EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
308 		return 1;
309 
310 	case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
311 		if (p1 == -2) {
312 			if (dctx->cofactor_mode != -1)
313 				return dctx->cofactor_mode;
314 			else {
315 				EC_KEY *ec_key = ctx->pkey->pkey.ec;
316 				return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
317 			}
318 		} else if (p1 < -1 || p1 > 1)
319 			return -2;
320 		dctx->cofactor_mode = p1;
321 		if (p1 != -1) {
322 			EC_KEY *ec_key = ctx->pkey->pkey.ec;
323 			if (!ec_key->group)
324 				return -2;
325 			/* If cofactor is 1 cofactor mode does nothing */
326 			if (BN_is_one(ec_key->group->cofactor))
327 				return 1;
328 			if (!dctx->co_key) {
329 				dctx->co_key = EC_KEY_dup(ec_key);
330 				if (!dctx->co_key)
331 					return 0;
332 			}
333 			if (p1)
334 				EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
335 			else
336 				EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
337 		} else {
338 			EC_KEY_free(dctx->co_key);
339 			dctx->co_key = NULL;
340 		}
341 		return 1;
342 
343 	case EVP_PKEY_CTRL_EC_KDF_TYPE:
344 		if (p1 == -2)
345 			return dctx->kdf_type;
346 		if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_63)
347 			return -2;
348 		dctx->kdf_type = p1;
349 		return 1;
350 
351 	case EVP_PKEY_CTRL_EC_KDF_MD:
352 		dctx->kdf_md = p2;
353 		return 1;
354 
355 	case EVP_PKEY_CTRL_GET_EC_KDF_MD:
356 		*(const EVP_MD **)p2 = dctx->kdf_md;
357 		return 1;
358 
359 	case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
360 		if (p1 <= 0)
361 			return -2;
362 		dctx->kdf_outlen = (size_t)p1;
363 		return 1;
364 
365 	case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
366 		*(int *)p2 = dctx->kdf_outlen;
367 		return 1;
368 
369 	case EVP_PKEY_CTRL_EC_KDF_UKM:
370 		free(dctx->kdf_ukm);
371 		dctx->kdf_ukm = p2;
372 		if (p2)
373 			dctx->kdf_ukmlen = p1;
374 		else
375 			dctx->kdf_ukmlen = 0;
376 		return 1;
377 
378 	case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
379 		*(unsigned char **)p2 = dctx->kdf_ukm;
380 		return dctx->kdf_ukmlen;
381 
382 	case EVP_PKEY_CTRL_MD:
383 		/* RFC 3279, RFC 5758 and NIST CSOR. */
384 		switch (EVP_MD_type(p2)) {
385 		case NID_sha1:
386 		case NID_ecdsa_with_SHA1:
387 		case NID_sha224:
388 		case NID_sha256:
389 		case NID_sha384:
390 		case NID_sha512:
391 		case NID_sha3_224:
392 		case NID_sha3_256:
393 		case NID_sha3_384:
394 		case NID_sha3_512:
395 			break;
396 		default:
397 			ECerror(EC_R_INVALID_DIGEST_TYPE);
398 			return 0;
399 		}
400 		dctx->md = p2;
401 		return 1;
402 
403 	case EVP_PKEY_CTRL_GET_MD:
404 		*(const EVP_MD **)p2 = dctx->md;
405 		return 1;
406 
407 	case EVP_PKEY_CTRL_PEER_KEY:
408 		/* Default behaviour is OK */
409 	case EVP_PKEY_CTRL_DIGESTINIT:
410 	case EVP_PKEY_CTRL_PKCS7_SIGN:
411 	case EVP_PKEY_CTRL_CMS_SIGN:
412 		return 1;
413 
414 	default:
415 		return -2;
416 
417 	}
418 }
419 
420 static int
421 pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx, const char *type, const char *value)
422 {
423 	if (!strcmp(type, "ec_paramgen_curve")) {
424 		int nid;
425 		nid = EC_curve_nist2nid(value);
426 		if (nid == NID_undef)
427 			nid = OBJ_sn2nid(value);
428 		if (nid == NID_undef)
429 			nid = OBJ_ln2nid(value);
430 		if (nid == NID_undef) {
431 			ECerror(EC_R_INVALID_CURVE);
432 			return 0;
433 		}
434 		return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
435 	} else if (strcmp(type, "ec_param_enc") == 0) {
436 		int param_enc;
437 		if (strcmp(value, "explicit") == 0)
438 			param_enc = 0;
439 		else if (strcmp(value, "named_curve") == 0)
440 			param_enc = OPENSSL_EC_NAMED_CURVE;
441 		else
442 			return -2;
443 		return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
444 	} else if (strcmp(type, "ecdh_kdf_md") == 0) {
445 		const EVP_MD *md;
446 		if ((md = EVP_get_digestbyname(value)) == NULL) {
447 			ECerror(EC_R_INVALID_DIGEST);
448 			return 0;
449 		}
450 		return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
451 	} else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
452 		int cofactor_mode;
453 		const char *errstr;
454 
455 		cofactor_mode = strtonum(value, -1, 1, &errstr);
456 		if (errstr != NULL)
457 			return -2;
458 		return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, cofactor_mode);
459 	}
460 
461 	return -2;
462 }
463 
464 static int
465 pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
466 {
467 	EC_KEY *ec = NULL;
468 	EC_PKEY_CTX *dctx = ctx->data;
469 	int ret = 0;
470 
471 	if (dctx->gen_group == NULL) {
472 		ECerror(EC_R_NO_PARAMETERS_SET);
473 		goto err;
474 	}
475 
476 	if ((ec = EC_KEY_new()) == NULL)
477 		goto err;
478 	if (!EC_KEY_set_group(ec, dctx->gen_group))
479 		goto err;
480 	if (!EVP_PKEY_assign_EC_KEY(pkey, ec))
481 		goto err;
482 	ec = NULL;
483 
484 	ret = 1;
485 
486  err:
487 	EC_KEY_free(ec);
488 
489 	return ret;
490 }
491 
492 static int
493 pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
494 {
495 	EC_KEY *ec = NULL;
496 	EC_PKEY_CTX *dctx = ctx->data;
497 	int ret = 0;
498 
499 	if (ctx->pkey == NULL && dctx->gen_group == NULL) {
500 		ECerror(EC_R_NO_PARAMETERS_SET);
501 		goto err;
502 	}
503 
504 	if ((ec = EC_KEY_new()) == NULL)
505 		goto err;
506 	if (!EVP_PKEY_set1_EC_KEY(pkey, ec))
507 		goto err;
508 
509 	if (ctx->pkey != NULL) {
510 		if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
511 			goto err;
512 	} else {
513 		if (!EC_KEY_set_group(ec, dctx->gen_group))
514 			goto err;
515 	}
516 
517 	if (!EC_KEY_generate_key(ec))
518 		goto err;
519 
520 	ret = 1;
521 
522  err:
523 	EC_KEY_free(ec);
524 
525 	return ret;
526 }
527 
528 const EVP_PKEY_METHOD ec_pkey_meth = {
529 	.pkey_id = EVP_PKEY_EC,
530 
531 	.init = pkey_ec_init,
532 	.copy = pkey_ec_copy,
533 	.cleanup = pkey_ec_cleanup,
534 
535 	.paramgen = pkey_ec_paramgen,
536 
537 	.keygen = pkey_ec_keygen,
538 
539 	.sign = pkey_ec_sign,
540 
541 	.verify = pkey_ec_verify,
542 
543 	.derive = pkey_ec_kdf_derive,
544 
545 	.ctrl = pkey_ec_ctrl,
546 	.ctrl_str = pkey_ec_ctrl_str
547 };
548