1 /* $OpenBSD: ec_pmeth.c,v 1.23 2024/10/19 14:41:03 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
pkey_ec_init(EVP_PKEY_CTX * ctx)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
pkey_ec_copy(EVP_PKEY_CTX * dst,EVP_PKEY_CTX * src)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
pkey_ec_cleanup(EVP_PKEY_CTX * ctx)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
pkey_ec_sign(EVP_PKEY_CTX * ctx,unsigned char * sig,size_t * siglen,const unsigned char * tbs,size_t tbslen)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
pkey_ec_verify(EVP_PKEY_CTX * ctx,const unsigned char * sig,size_t siglen,const unsigned char * tbs,size_t tbslen)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
pkey_ec_derive(EVP_PKEY_CTX * ctx,unsigned char * key,size_t * keylen)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
pkey_ec_kdf_derive(EVP_PKEY_CTX * ctx,unsigned char * key,size_t * keylen)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
pkey_ec_ctrl(EVP_PKEY_CTX * ctx,int type,int p1,void * p2)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
pkey_ec_ctrl_str(EVP_PKEY_CTX * ctx,const char * type,const char * value)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
pkey_ec_paramgen(EVP_PKEY_CTX * ctx,EVP_PKEY * pkey)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
pkey_ec_keygen(EVP_PKEY_CTX * ctx,EVP_PKEY * pkey)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