1 /* $OpenBSD: ec_pmeth.c,v 1.13 2021/12/04 16:08:32 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 <string.h>
61
62 #include <openssl/asn1t.h>
63 #include <openssl/ec.h>
64 #include <openssl/ecdsa.h>
65 #include <openssl/err.h>
66 #include <openssl/evp.h>
67 #include <openssl/x509.h>
68
69 #include "bn_lcl.h"
70 #include "ec_lcl.h"
71 #include "ech_locl.h"
72 #include "evp_locl.h"
73
74 /* EC pkey context structure */
75
76 typedef struct {
77 /* Key and paramgen group */
78 EC_GROUP *gen_group;
79 /* message digest */
80 const EVP_MD *md;
81 /* Duplicate key if custom cofactor needed */
82 EC_KEY *co_key;
83 /* Cofactor mode */
84 signed char cofactor_mode;
85 /* KDF (if any) to use for ECDH */
86 char kdf_type;
87 /* Message digest to use for key derivation */
88 const EVP_MD *kdf_md;
89 /* User key material */
90 unsigned char *kdf_ukm;
91 size_t kdf_ukmlen;
92 /* KDF output length */
93 size_t kdf_outlen;
94 } EC_PKEY_CTX;
95
96 static int
pkey_ec_init(EVP_PKEY_CTX * ctx)97 pkey_ec_init(EVP_PKEY_CTX * ctx)
98 {
99 EC_PKEY_CTX *dctx;
100
101 if ((dctx = calloc(1, sizeof(EC_PKEY_CTX))) == NULL) {
102 ECerror(ERR_R_MALLOC_FAILURE);
103 return 0;
104 }
105
106 dctx->cofactor_mode = -1;
107 dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
108
109 ctx->data = dctx;
110
111 return 1;
112 }
113
114 static int
pkey_ec_copy(EVP_PKEY_CTX * dst,EVP_PKEY_CTX * src)115 pkey_ec_copy(EVP_PKEY_CTX * dst, EVP_PKEY_CTX * src)
116 {
117 EC_PKEY_CTX *dctx, *sctx;
118 if (!pkey_ec_init(dst))
119 return 0;
120 sctx = src->data;
121 dctx = dst->data;
122 if (sctx->gen_group) {
123 dctx->gen_group = EC_GROUP_dup(sctx->gen_group);
124 if (!dctx->gen_group)
125 return 0;
126 }
127 dctx->md = sctx->md;
128
129 if (sctx->co_key) {
130 dctx->co_key = EC_KEY_dup(sctx->co_key);
131 if (!dctx->co_key)
132 return 0;
133 }
134 dctx->kdf_type = sctx->kdf_type;
135 dctx->kdf_md = sctx->kdf_md;
136 dctx->kdf_outlen = sctx->kdf_outlen;
137 if (sctx->kdf_ukm) {
138 if ((dctx->kdf_ukm = calloc(1, sctx->kdf_ukmlen)) == NULL)
139 return 0;
140 memcpy(dctx->kdf_ukm, sctx->kdf_ukm, sctx->kdf_ukmlen);
141 } else
142 dctx->kdf_ukm = NULL;
143
144 dctx->kdf_ukmlen = sctx->kdf_ukmlen;
145
146 return 1;
147 }
148
149 static void
pkey_ec_cleanup(EVP_PKEY_CTX * ctx)150 pkey_ec_cleanup(EVP_PKEY_CTX * ctx)
151 {
152 EC_PKEY_CTX *dctx = ctx->data;
153
154 if (dctx != NULL) {
155 EC_GROUP_free(dctx->gen_group);
156 EC_KEY_free(dctx->co_key);
157 free(dctx->kdf_ukm);
158 free(dctx);
159 ctx->data = NULL;
160 }
161 }
162
163 static int
pkey_ec_sign(EVP_PKEY_CTX * ctx,unsigned char * sig,size_t * siglen,const unsigned char * tbs,size_t tbslen)164 pkey_ec_sign(EVP_PKEY_CTX * ctx, unsigned char *sig, size_t * siglen,
165 const unsigned char *tbs, size_t tbslen)
166 {
167 int ret, type;
168 unsigned int sltmp;
169 EC_PKEY_CTX *dctx = ctx->data;
170 EC_KEY *ec = ctx->pkey->pkey.ec;
171
172 if (!sig) {
173 *siglen = ECDSA_size(ec);
174 return 1;
175 } else if (*siglen < (size_t) ECDSA_size(ec)) {
176 ECerror(EC_R_BUFFER_TOO_SMALL);
177 return 0;
178 }
179 if (dctx->md)
180 type = EVP_MD_type(dctx->md);
181 else
182 type = NID_sha1;
183
184 ret = ECDSA_sign(type, tbs, tbslen, sig, &sltmp, ec);
185 if (ret <= 0)
186 return ret;
187 *siglen = (size_t) sltmp;
188 return 1;
189 }
190
191 static int
pkey_ec_verify(EVP_PKEY_CTX * ctx,const unsigned char * sig,size_t siglen,const unsigned char * tbs,size_t tbslen)192 pkey_ec_verify(EVP_PKEY_CTX * ctx,
193 const unsigned char *sig, size_t siglen,
194 const unsigned char *tbs, size_t tbslen)
195 {
196 int ret, type;
197 EC_PKEY_CTX *dctx = ctx->data;
198 EC_KEY *ec = ctx->pkey->pkey.ec;
199
200 if (dctx->md)
201 type = EVP_MD_type(dctx->md);
202 else
203 type = NID_sha1;
204
205 ret = ECDSA_verify(type, tbs, tbslen, sig, siglen, ec);
206
207 return ret;
208 }
209
210 static int
pkey_ec_derive(EVP_PKEY_CTX * ctx,unsigned char * key,size_t * keylen)211 pkey_ec_derive(EVP_PKEY_CTX * ctx, unsigned char *key, size_t * keylen)
212 {
213 int ret;
214 size_t outlen;
215 const EC_POINT *pubkey = NULL;
216 EC_KEY *eckey;
217 EC_PKEY_CTX *dctx = ctx->data;
218
219 if (!ctx->pkey || !ctx->peerkey) {
220 ECerror(EC_R_KEYS_NOT_SET);
221 return 0;
222 }
223
224 eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
225 if (!key) {
226 const EC_GROUP *group;
227 group = EC_KEY_get0_group(eckey);
228 *keylen = (EC_GROUP_get_degree(group) + 7) / 8;
229 return 1;
230 }
231 pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);
232
233 /*
234 * NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is
235 * not an error, the result is truncated.
236 */
237
238 outlen = *keylen;
239
240 ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
241 if (ret <= 0)
242 return 0;
243
244 *keylen = ret;
245
246 return 1;
247 }
248
249 static int
pkey_ec_kdf_derive(EVP_PKEY_CTX * ctx,unsigned char * key,size_t * keylen)250 pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
251 {
252 EC_PKEY_CTX *dctx = ctx->data;
253 unsigned char *ktmp = NULL;
254 size_t ktmplen;
255 int rv = 0;
256
257 if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
258 return pkey_ec_derive(ctx, key, keylen);
259
260 if (!key) {
261 *keylen = dctx->kdf_outlen;
262 return 1;
263 }
264 if (*keylen != dctx->kdf_outlen)
265 return 0;
266 if (!pkey_ec_derive(ctx, NULL, &ktmplen))
267 return 0;
268 if ((ktmp = calloc(1, ktmplen)) == NULL) {
269 ECerror(ERR_R_MALLOC_FAILURE);
270 return 0;
271 }
272 if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
273 goto err;
274 /* Do KDF stuff */
275 if (!ecdh_KDF_X9_63(key, *keylen, ktmp, ktmplen, dctx->kdf_ukm,
276 dctx->kdf_ukmlen, dctx->kdf_md))
277 goto err;
278 rv = 1;
279
280 err:
281 freezero(ktmp, ktmplen);
282
283 return rv;
284 }
285
286 static int
pkey_ec_ctrl(EVP_PKEY_CTX * ctx,int type,int p1,void * p2)287 pkey_ec_ctrl(EVP_PKEY_CTX * ctx, int type, int p1, void *p2)
288 {
289 EC_PKEY_CTX *dctx = ctx->data;
290 EC_GROUP *group;
291
292 switch (type) {
293 case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
294 group = EC_GROUP_new_by_curve_name(p1);
295 if (group == NULL) {
296 ECerror(EC_R_INVALID_CURVE);
297 return 0;
298 }
299 EC_GROUP_free(dctx->gen_group);
300 dctx->gen_group = group;
301 return 1;
302
303 case EVP_PKEY_CTRL_EC_PARAM_ENC:
304 if (!dctx->gen_group) {
305 ECerror(EC_R_NO_PARAMETERS_SET);
306 return 0;
307 }
308 EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
309 return 1;
310
311 case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
312 if (p1 == -2) {
313 if (dctx->cofactor_mode != -1)
314 return dctx->cofactor_mode;
315 else {
316 EC_KEY *ec_key = ctx->pkey->pkey.ec;
317 return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
318 }
319 } else if (p1 < -1 || p1 > 1)
320 return -2;
321 dctx->cofactor_mode = p1;
322 if (p1 != -1) {
323 EC_KEY *ec_key = ctx->pkey->pkey.ec;
324 if (!ec_key->group)
325 return -2;
326 /* If cofactor is 1 cofactor mode does nothing */
327 if (BN_is_one(&ec_key->group->cofactor))
328 return 1;
329 if (!dctx->co_key) {
330 dctx->co_key = EC_KEY_dup(ec_key);
331 if (!dctx->co_key)
332 return 0;
333 }
334 if (p1)
335 EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
336 else
337 EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
338 } else {
339 EC_KEY_free(dctx->co_key);
340 dctx->co_key = NULL;
341 }
342 return 1;
343
344 case EVP_PKEY_CTRL_EC_KDF_TYPE:
345 if (p1 == -2)
346 return dctx->kdf_type;
347 if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_63)
348 return -2;
349 dctx->kdf_type = p1;
350 return 1;
351
352 case EVP_PKEY_CTRL_EC_KDF_MD:
353 dctx->kdf_md = p2;
354 return 1;
355
356 case EVP_PKEY_CTRL_GET_EC_KDF_MD:
357 *(const EVP_MD **)p2 = dctx->kdf_md;
358 return 1;
359
360 case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
361 if (p1 <= 0)
362 return -2;
363 dctx->kdf_outlen = (size_t)p1;
364 return 1;
365
366 case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
367 *(int *)p2 = dctx->kdf_outlen;
368 return 1;
369
370 case EVP_PKEY_CTRL_EC_KDF_UKM:
371 free(dctx->kdf_ukm);
372 dctx->kdf_ukm = p2;
373 if (p2)
374 dctx->kdf_ukmlen = p1;
375 else
376 dctx->kdf_ukmlen = 0;
377 return 1;
378
379 case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
380 *(unsigned char **)p2 = dctx->kdf_ukm;
381 return dctx->kdf_ukmlen;
382
383 case EVP_PKEY_CTRL_MD:
384 if (EVP_MD_type((const EVP_MD *) p2) != NID_sha1 &&
385 EVP_MD_type((const EVP_MD *) p2) != NID_ecdsa_with_SHA1 &&
386 EVP_MD_type((const EVP_MD *) p2) != NID_sha224 &&
387 EVP_MD_type((const EVP_MD *) p2) != NID_sha256 &&
388 EVP_MD_type((const EVP_MD *) p2) != NID_sha384 &&
389 EVP_MD_type((const EVP_MD *) p2) != NID_sha512) {
390 ECerror(EC_R_INVALID_DIGEST_TYPE);
391 return 0;
392 }
393 dctx->md = p2;
394 return 1;
395
396 case EVP_PKEY_CTRL_GET_MD:
397 *(const EVP_MD **)p2 = dctx->md;
398 return 1;
399
400 case EVP_PKEY_CTRL_PEER_KEY:
401 /* Default behaviour is OK */
402 case EVP_PKEY_CTRL_DIGESTINIT:
403 case EVP_PKEY_CTRL_PKCS7_SIGN:
404 case EVP_PKEY_CTRL_CMS_SIGN:
405 return 1;
406
407 default:
408 return -2;
409
410 }
411 }
412
413 static int
pkey_ec_ctrl_str(EVP_PKEY_CTX * ctx,const char * type,const char * value)414 pkey_ec_ctrl_str(EVP_PKEY_CTX * ctx, const char *type, const char *value)
415 {
416 if (!strcmp(type, "ec_paramgen_curve")) {
417 int nid;
418 nid = EC_curve_nist2nid(value);
419 if (nid == NID_undef)
420 nid = OBJ_sn2nid(value);
421 if (nid == NID_undef)
422 nid = OBJ_ln2nid(value);
423 if (nid == NID_undef) {
424 ECerror(EC_R_INVALID_CURVE);
425 return 0;
426 }
427 return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
428 } else if (strcmp(type, "ec_param_enc") == 0) {
429 int param_enc;
430 if (strcmp(value, "explicit") == 0)
431 param_enc = 0;
432 else if (strcmp(value, "named_curve") == 0)
433 param_enc = OPENSSL_EC_NAMED_CURVE;
434 else
435 return -2;
436 return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
437 } else if (strcmp(type, "ecdh_kdf_md") == 0) {
438 const EVP_MD *md;
439 if ((md = EVP_get_digestbyname(value)) == NULL) {
440 ECerror(EC_R_INVALID_DIGEST);
441 return 0;
442 }
443 return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
444 } else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
445 int co_mode;
446 co_mode = atoi(value);
447 return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
448 }
449 return -2;
450 }
451
452 static int
pkey_ec_paramgen(EVP_PKEY_CTX * ctx,EVP_PKEY * pkey)453 pkey_ec_paramgen(EVP_PKEY_CTX * ctx, EVP_PKEY * pkey)
454 {
455 EC_KEY *ec = NULL;
456 EC_PKEY_CTX *dctx = ctx->data;
457 int ret = 0;
458 if (dctx->gen_group == NULL) {
459 ECerror(EC_R_NO_PARAMETERS_SET);
460 return 0;
461 }
462 ec = EC_KEY_new();
463 if (!ec)
464 return 0;
465 ret = EC_KEY_set_group(ec, dctx->gen_group);
466 if (ret)
467 EVP_PKEY_assign_EC_KEY(pkey, ec);
468 else
469 EC_KEY_free(ec);
470 return ret;
471 }
472
473 static int
pkey_ec_keygen(EVP_PKEY_CTX * ctx,EVP_PKEY * pkey)474 pkey_ec_keygen(EVP_PKEY_CTX * ctx, EVP_PKEY * pkey)
475 {
476 EC_KEY *ec = NULL;
477 EC_PKEY_CTX *dctx = ctx->data;
478
479 if (ctx->pkey == NULL && dctx->gen_group == NULL) {
480 ECerror(EC_R_NO_PARAMETERS_SET);
481 return 0;
482 }
483 ec = EC_KEY_new();
484 if (ec == NULL)
485 return 0;
486 if (!EVP_PKEY_assign_EC_KEY(pkey, ec)) {
487 EC_KEY_free(ec);
488 return 0;
489 }
490 /* Note: if error is returned, we count on caller to free pkey->pkey.ec */
491 if (ctx->pkey != NULL) {
492 if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
493 return 0;
494 } else {
495 if (!EC_KEY_set_group(ec, dctx->gen_group))
496 return 0;
497 }
498
499 return EC_KEY_generate_key(ec);
500 }
501
502 const EVP_PKEY_METHOD ec_pkey_meth = {
503 .pkey_id = EVP_PKEY_EC,
504
505 .init = pkey_ec_init,
506 .copy = pkey_ec_copy,
507 .cleanup = pkey_ec_cleanup,
508
509 .paramgen = pkey_ec_paramgen,
510
511 .keygen = pkey_ec_keygen,
512
513 .sign = pkey_ec_sign,
514
515 .verify = pkey_ec_verify,
516
517 .derive = pkey_ec_kdf_derive,
518
519 .ctrl = pkey_ec_ctrl,
520 .ctrl_str = pkey_ec_ctrl_str
521 };
522