1 /* $OpenBSD: ec_pmeth.c,v 1.17 2023/04/25 15:48:48 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_local.h" 70 #include "ec_local.h" 71 #include "ech_local.h" 72 #include "evp_local.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 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 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 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 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 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 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 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 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 /* RFC 3279, RFC 5758 and NIST CSOR. */ 385 if (EVP_MD_type((const EVP_MD *) p2) != NID_sha1 && 386 EVP_MD_type((const EVP_MD *) p2) != NID_ecdsa_with_SHA1 && 387 EVP_MD_type((const EVP_MD *) p2) != NID_sha224 && 388 EVP_MD_type((const EVP_MD *) p2) != NID_sha256 && 389 EVP_MD_type((const EVP_MD *) p2) != NID_sha384 && 390 EVP_MD_type((const EVP_MD *) p2) != NID_sha512 && 391 EVP_MD_type((const EVP_MD *) p2) != NID_sha3_224 && 392 EVP_MD_type((const EVP_MD *) p2) != NID_sha3_256 && 393 EVP_MD_type((const EVP_MD *) p2) != NID_sha3_384 && 394 EVP_MD_type((const EVP_MD *) p2) != NID_sha3_512) { 395 ECerror(EC_R_INVALID_DIGEST_TYPE); 396 return 0; 397 } 398 dctx->md = p2; 399 return 1; 400 401 case EVP_PKEY_CTRL_GET_MD: 402 *(const EVP_MD **)p2 = dctx->md; 403 return 1; 404 405 case EVP_PKEY_CTRL_PEER_KEY: 406 /* Default behaviour is OK */ 407 case EVP_PKEY_CTRL_DIGESTINIT: 408 case EVP_PKEY_CTRL_PKCS7_SIGN: 409 case EVP_PKEY_CTRL_CMS_SIGN: 410 return 1; 411 412 default: 413 return -2; 414 415 } 416 } 417 418 static int 419 pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx, const char *type, const char *value) 420 { 421 if (!strcmp(type, "ec_paramgen_curve")) { 422 int nid; 423 nid = EC_curve_nist2nid(value); 424 if (nid == NID_undef) 425 nid = OBJ_sn2nid(value); 426 if (nid == NID_undef) 427 nid = OBJ_ln2nid(value); 428 if (nid == NID_undef) { 429 ECerror(EC_R_INVALID_CURVE); 430 return 0; 431 } 432 return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid); 433 } else if (strcmp(type, "ec_param_enc") == 0) { 434 int param_enc; 435 if (strcmp(value, "explicit") == 0) 436 param_enc = 0; 437 else if (strcmp(value, "named_curve") == 0) 438 param_enc = OPENSSL_EC_NAMED_CURVE; 439 else 440 return -2; 441 return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc); 442 } else if (strcmp(type, "ecdh_kdf_md") == 0) { 443 const EVP_MD *md; 444 if ((md = EVP_get_digestbyname(value)) == NULL) { 445 ECerror(EC_R_INVALID_DIGEST); 446 return 0; 447 } 448 return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md); 449 } else if (strcmp(type, "ecdh_cofactor_mode") == 0) { 450 int co_mode; 451 co_mode = atoi(value); 452 return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode); 453 } 454 return -2; 455 } 456 457 static int 458 pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey) 459 { 460 EC_KEY *ec = NULL; 461 EC_PKEY_CTX *dctx = ctx->data; 462 int ret = 0; 463 if (dctx->gen_group == NULL) { 464 ECerror(EC_R_NO_PARAMETERS_SET); 465 return 0; 466 } 467 ec = EC_KEY_new(); 468 if (!ec) 469 return 0; 470 ret = EC_KEY_set_group(ec, dctx->gen_group); 471 if (ret) 472 EVP_PKEY_assign_EC_KEY(pkey, ec); 473 else 474 EC_KEY_free(ec); 475 return ret; 476 } 477 478 static int 479 pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey) 480 { 481 EC_KEY *ec = NULL; 482 EC_PKEY_CTX *dctx = ctx->data; 483 484 if (ctx->pkey == NULL && dctx->gen_group == NULL) { 485 ECerror(EC_R_NO_PARAMETERS_SET); 486 return 0; 487 } 488 ec = EC_KEY_new(); 489 if (ec == NULL) 490 return 0; 491 if (!EVP_PKEY_assign_EC_KEY(pkey, ec)) { 492 EC_KEY_free(ec); 493 return 0; 494 } 495 /* Note: if error is returned, we count on caller to free pkey->pkey.ec */ 496 if (ctx->pkey != NULL) { 497 if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey)) 498 return 0; 499 } else { 500 if (!EC_KEY_set_group(ec, dctx->gen_group)) 501 return 0; 502 } 503 504 return EC_KEY_generate_key(ec); 505 } 506 507 const EVP_PKEY_METHOD ec_pkey_meth = { 508 .pkey_id = EVP_PKEY_EC, 509 510 .init = pkey_ec_init, 511 .copy = pkey_ec_copy, 512 .cleanup = pkey_ec_cleanup, 513 514 .paramgen = pkey_ec_paramgen, 515 516 .keygen = pkey_ec_keygen, 517 518 .sign = pkey_ec_sign, 519 520 .verify = pkey_ec_verify, 521 522 .derive = pkey_ec_kdf_derive, 523 524 .ctrl = pkey_ec_ctrl, 525 .ctrl_str = pkey_ec_ctrl_str 526 }; 527