crypto/ec/ec_pmeth.c

   1 /*
   2  * Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include "internal/cryptlib.h"
  12 #include <openssl/asn1t.h>
  13 #include <openssl/x509.h>
  14 #include <openssl/ec.h>
  15 #include "ec_lcl.h"
  16 #include <openssl/evp.h>
  17 #include "internal/evp_int.h"
  18
  19 #if !defined(OPENSSL_NO_SM2)
  20 # include <openssl/sm2.h>
  21 #endif
  22
  23 /* EC pkey context structure */
  24
  25 typedef struct {
  26     /* Key and paramgen group */
  27     EC_GROUP *gen_group;
  28     /* message digest */
  29     const EVP_MD *md;
  30     /* Duplicate key if custom cofactor needed */
  31     EC_KEY *co_key;
  32     /* Cofactor mode */
  33     signed char cofactor_mode;
  34     /* KDF (if any) to use for ECDH */
  35     char kdf_type;
  36     /* Message digest to use for key derivation */
  37     const EVP_MD *kdf_md;
  38     /* User key material */
  39     unsigned char *kdf_ukm;
  40     size_t kdf_ukmlen;
  41     /* KDF output length */
  42     size_t kdf_outlen;
  43 } EC_PKEY_CTX;
  44
  45 static int pkey_ec_init(EVP_PKEY_CTX *ctx)
  46 {
  47     EC_PKEY_CTX *dctx;
  48
  49     if ((dctx = OPENSSL_zalloc(sizeof(*dctx))) == NULL) {
  50         ECerr(EC_F_PKEY_EC_INIT, ERR_R_MALLOC_FAILURE);
  51         return 0;
  52     }
  53
  54     dctx->cofactor_mode = -1;
  55     dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
  56     ctx->data = dctx;
  57     return 1;
  58 }
  59
  60 static int pkey_ec_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
  61 {
  62     EC_PKEY_CTX *dctx, *sctx;
  63     if (!pkey_ec_init(dst))
  64         return 0;
  65     sctx = src->data;
  66     dctx = dst->data;
  67     if (sctx->gen_group) {
  68         dctx->gen_group = EC_GROUP_dup(sctx->gen_group);
  69         if (!dctx->gen_group)
  70             return 0;
  71     }
  72     dctx->md = sctx->md;
  73
  74     if (sctx->co_key) {
  75         dctx->co_key = EC_KEY_dup(sctx->co_key);
  76         if (!dctx->co_key)
  77             return 0;
  78     }
  79     dctx->kdf_type = sctx->kdf_type;
  80     dctx->kdf_md = sctx->kdf_md;
  81     dctx->kdf_outlen = sctx->kdf_outlen;
  82     if (sctx->kdf_ukm) {
  83         dctx->kdf_ukm = OPENSSL_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);
  84         if (!dctx->kdf_ukm)
  85             return 0;
  86     } else
  87         dctx->kdf_ukm = NULL;
  88     dctx->kdf_ukmlen = sctx->kdf_ukmlen;
  89     return 1;
  90 }
  91
  92 static void pkey_ec_cleanup(EVP_PKEY_CTX *ctx)
  93 {
  94     EC_PKEY_CTX *dctx = ctx->data;
  95     if (dctx) {
  96         EC_GROUP_free(dctx->gen_group);
  97         EC_KEY_free(dctx->co_key);
  98         OPENSSL_free(dctx->kdf_ukm);
  99         OPENSSL_free(dctx);
 100     }
 101 }
 102
 103 static int pkey_ec_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
 104                         const unsigned char *tbs, size_t tbslen)
 105 {
 106     int ret, type;
 107     unsigned int sltmp;
 108     EC_PKEY_CTX *dctx = ctx->data;
 109     EC_KEY *ec = ctx->pkey->pkey.ec;
 110     const int ec_nid = EC_GROUP_get_curve_name(EC_KEY_get0_group(ec));
 111
 112     if (!sig) {
 113         *siglen = ECDSA_size(ec);
 114         return 1;
 115     } else if (*siglen < (size_t)ECDSA_size(ec)) {
 116         ECerr(EC_F_PKEY_EC_SIGN, EC_R_BUFFER_TOO_SMALL);
 117         return 0;
 118     }
 119
 120     if (dctx->md)
 121         type = EVP_MD_type(dctx->md);
 122     else
 123         type = NID_sha1;
 124
 125     if (ec_nid == NID_sm2) {
 126 #if defined(OPENSSL_NO_SM2)
 127         return -1;
 128 #else
 129         ret = SM2_sign(type, tbs, tbslen, sig, &sltmp, ec);
 130 #endif
 131     } else {
 132         ret = ECDSA_sign(type, tbs, tbslen, sig, &sltmp, ec);
 133     }
 134
 135     if (ret <= 0)
 136         return ret;
 137     *siglen = (size_t)sltmp;
 138     return 1;
 139 }
 140
 141 static int pkey_ec_verify(EVP_PKEY_CTX *ctx,
 142                           const unsigned char *sig, size_t siglen,
 143                           const unsigned char *tbs, size_t tbslen)
 144 {
 145     int ret, type;
 146     EC_PKEY_CTX *dctx = ctx->data;
 147     EC_KEY *ec = ctx->pkey->pkey.ec;
 148     const int ec_nid = EC_GROUP_get_curve_name(EC_KEY_get0_group(ec));
 149
 150     if (dctx->md)
 151         type = EVP_MD_type(dctx->md);
 152     else
 153         type = NID_sha1;
 154
 155     if (ec_nid == NID_sm2) {
 156 #if defined(OPENSSL_NO_SM2)
 157         ret = -1;
 158 #else
 159         ret = SM2_verify(type, tbs, tbslen, sig, siglen, ec);
 160 #endif
 161     } else {
 162         ret = ECDSA_verify(type, tbs, tbslen, sig, siglen, ec);
 163     }
 164
 165     return ret;
 166 }
 167
 168 #ifndef OPENSSL_NO_EC
 169 static int pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
 170 {
 171     int ret;
 172     size_t outlen;
 173     const EC_POINT *pubkey = NULL;
 174     EC_KEY *eckey;
 175     EC_PKEY_CTX *dctx = ctx->data;
 176     if (!ctx->pkey || !ctx->peerkey) {
 177         ECerr(EC_F_PKEY_EC_DERIVE, EC_R_KEYS_NOT_SET);
 178         return 0;
 179     }
 180
 181     eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
 182
 183     if (!key) {
 184         const EC_GROUP *group;
 185         group = EC_KEY_get0_group(eckey);
 186         *keylen = (EC_GROUP_get_degree(group) + 7) / 8;
 187         return 1;
 188     }
 189     pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);
 190
 191     /*
 192      * NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is not
 193      * an error, the result is truncated.
 194      */
 195
 196     outlen = *keylen;
 197
 198     ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
 199     if (ret <= 0)
 200         return 0;
 201     *keylen = ret;
 202     return 1;
 203 }
 204
 205 static int pkey_ecies_encrypt(EVP_PKEY_CTX *ctx,
 206                               unsigned char *out, size_t *outlen,
 207                               const unsigned char *in, size_t inlen)
 208 {
 209     int ret;
 210     EC_KEY *ec = ctx->pkey->pkey.ec;
 211     const int ec_nid = EC_GROUP_get_curve_name(EC_KEY_get0_group(ec));
 212
 213     if (ec_nid == NID_sm2) {
 214 # if defined(OPENSSL_NO_SM2)
 215         ret = -1;
 216 # else
 217         int md_type;
 218         EC_PKEY_CTX *dctx = ctx->data;
 219
 220         if (dctx->md)
 221             md_type = EVP_MD_type(dctx->md);
 222         else
 223             md_type = NID_sm3;
 224
 225         if (out == NULL) {
 226             *outlen = SM2_ciphertext_size(ec, EVP_get_digestbynid(md_type),
 227                                           inlen);
 228             ret = 1;
 229         }
 230         else {
 231             ret = SM2_encrypt(ec, EVP_get_digestbynid(md_type),
 232                               in, inlen, out, outlen);
 233         }
 234 # endif
 235     } else {
 236         /* standard ECIES not implemented */
 237         ret = -1;
 238     }
 239
 240     return ret;
 241 }
 242
 243 static int pkey_ecies_decrypt(EVP_PKEY_CTX *ctx,
 244                               unsigned char *out, size_t *outlen,
 245                               const unsigned char *in, size_t inlen)
 246 {
 247     int ret;
 248     EC_KEY *ec = ctx->pkey->pkey.ec;
 249     const int ec_nid = EC_GROUP_get_curve_name(EC_KEY_get0_group(ec));
 250
 251     if (ec_nid == NID_sm2) {
 252 # if defined(OPENSSL_NO_SM2)
 253         ret = -1;
 254 # else
 255         int md_type;
 256         EC_PKEY_CTX *dctx = ctx->data;
 257
 258         if (dctx->md)
 259             md_type = EVP_MD_type(dctx->md);
 260         else
 261             md_type = NID_sm3;
 262
 263         if (out == NULL) {
 264             *outlen = SM2_plaintext_size(ec, EVP_get_digestbynid(md_type),
 265                                          inlen);
 266             ret = 1;
 267         }
 268         else {
 269             ret = SM2_decrypt(ec, EVP_get_digestbynid(md_type),
 270                               in, inlen, out, outlen);
 271         }
 272 # endif
 273     } else {
 274         /* standard ECIES not implemented */
 275         ret = -1;
 276     }
 277
 278     return ret;
 279 }
 280
 281 static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
 282                               unsigned char *key, size_t *keylen)
 283 {
 284     EC_PKEY_CTX *dctx = ctx->data;
 285     unsigned char *ktmp = NULL;
 286     size_t ktmplen;
 287     int rv = 0;
 288     if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
 289         return pkey_ec_derive(ctx, key, keylen);
 290     if (!key) {
 291         *keylen = dctx->kdf_outlen;
 292         return 1;
 293     }
 294     if (*keylen != dctx->kdf_outlen)
 295         return 0;
 296     if (!pkey_ec_derive(ctx, NULL, &ktmplen))
 297         return 0;
 298     if ((ktmp = OPENSSL_malloc(ktmplen)) == NULL) {
 299         ECerr(EC_F_PKEY_EC_KDF_DERIVE, ERR_R_MALLOC_FAILURE);
 300         return 0;
 301     }
 302     if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
 303         goto err;
 304     /* Do KDF stuff */
 305     if (!ECDH_KDF_X9_62(key, *keylen, ktmp, ktmplen,
 306                         dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md))
 307         goto err;
 308     rv = 1;
 309
 310  err:
 311     OPENSSL_clear_free(ktmp, ktmplen);
 312     return rv;
 313 }
 314 #endif
 315
 316 static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 317 {
 318     EC_PKEY_CTX *dctx = ctx->data;
 319     EC_GROUP *group;
 320     switch (type) {
 321     case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
 322         group = EC_GROUP_new_by_curve_name(p1);
 323         if (group == NULL) {
 324             ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_CURVE);
 325             return 0;
 326         }
 327         EC_GROUP_free(dctx->gen_group);
 328         dctx->gen_group = group;
 329         return 1;
 330
 331     case EVP_PKEY_CTRL_EC_PARAM_ENC:
 332         if (!dctx->gen_group) {
 333             ECerr(EC_F_PKEY_EC_CTRL, EC_R_NO_PARAMETERS_SET);
 334             return 0;
 335         }
 336         EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
 337         return 1;
 338
 339 #ifndef OPENSSL_NO_EC
 340     case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
 341         if (p1 == -2) {
 342             if (dctx->cofactor_mode != -1)
 343                 return dctx->cofactor_mode;
 344             else {
 345                 EC_KEY *ec_key = ctx->pkey->pkey.ec;
 346                 return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
 347             }
 348         } else if (p1 < -1 || p1 > 1)
 349             return -2;
 350         dctx->cofactor_mode = p1;
 351         if (p1 != -1) {
 352             EC_KEY *ec_key = ctx->pkey->pkey.ec;
 353             if (!ec_key->group)
 354                 return -2;
 355             /* If cofactor is 1 cofactor mode does nothing */
 356             if (BN_is_one(ec_key->group->cofactor))
 357                 return 1;
 358             if (!dctx->co_key) {
 359                 dctx->co_key = EC_KEY_dup(ec_key);
 360                 if (!dctx->co_key)
 361                     return 0;
 362             }
 363             if (p1)
 364                 EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
 365             else
 366                 EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
 367         } else {
 368             EC_KEY_free(dctx->co_key);
 369             dctx->co_key = NULL;
 370         }
 371         return 1;
 372 #endif
 373
 374     case EVP_PKEY_CTRL_EC_KDF_TYPE:
 375         if (p1 == -2)
 376             return dctx->kdf_type;
 377         if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_62)
 378             return -2;
 379         dctx->kdf_type = p1;
 380         return 1;
 381
 382     case EVP_PKEY_CTRL_EC_KDF_MD:
 383         dctx->kdf_md = p2;
 384         return 1;
 385
 386     case EVP_PKEY_CTRL_GET_EC_KDF_MD:
 387         *(const EVP_MD **)p2 = dctx->kdf_md;
 388         return 1;
 389
 390     case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
 391         if (p1 <= 0)
 392             return -2;
 393         dctx->kdf_outlen = (size_t)p1;
 394         return 1;
 395
 396     case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
 397         *(int *)p2 = dctx->kdf_outlen;
 398         return 1;
 399
 400     case EVP_PKEY_CTRL_EC_KDF_UKM:
 401         OPENSSL_free(dctx->kdf_ukm);
 402         dctx->kdf_ukm = p2;
 403         if (p2)
 404             dctx->kdf_ukmlen = p1;
 405         else
 406             dctx->kdf_ukmlen = 0;
 407         return 1;
 408
 409     case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
 410         *(unsigned char **)p2 = dctx->kdf_ukm;
 411         return dctx->kdf_ukmlen;
 412
 413     case EVP_PKEY_CTRL_MD:
 414         if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1 &&
 415             EVP_MD_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
 416             EVP_MD_type((const EVP_MD *)p2) != NID_sha224 &&
 417             EVP_MD_type((const EVP_MD *)p2) != NID_sha256 &&
 418             EVP_MD_type((const EVP_MD *)p2) != NID_sha384 &&
 419             EVP_MD_type((const EVP_MD *)p2) != NID_sha512 &&
 420             EVP_MD_type((const EVP_MD *)p2) != NID_sm3) {
 421             ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_DIGEST_TYPE);
 422             return 0;
 423         }
 424         dctx->md = p2;
 425         return 1;
 426
 427     case EVP_PKEY_CTRL_GET_MD:
 428         *(const EVP_MD **)p2 = dctx->md;
 429         return 1;
 430
 431     case EVP_PKEY_CTRL_PEER_KEY:
 432         /* Default behaviour is OK */
 433     case EVP_PKEY_CTRL_DIGESTINIT:
 434     case EVP_PKEY_CTRL_PKCS7_SIGN:
 435     case EVP_PKEY_CTRL_CMS_SIGN:
 436         return 1;
 437
 438     default:
 439         return -2;
 440
 441     }
 442 }
 443
 444 static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
 445                             const char *type, const char *value)
 446 {
 447     if (strcmp(type, "ec_paramgen_curve") == 0) {
 448         int nid;
 449         nid = EC_curve_nist2nid(value);
 450         if (nid == NID_undef)
 451             nid = OBJ_sn2nid(value);
 452         if (nid == NID_undef)
 453             nid = OBJ_ln2nid(value);
 454         if (nid == NID_undef) {
 455             ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_CURVE);
 456             return 0;
 457         }
 458         return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
 459     } else if (strcmp(type, "ec_param_enc") == 0) {
 460         int param_enc;
 461         if (strcmp(value, "explicit") == 0)
 462             param_enc = 0;
 463         else if (strcmp(value, "named_curve") == 0)
 464             param_enc = OPENSSL_EC_NAMED_CURVE;
 465         else
 466             return -2;
 467         return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
 468     } else if (strcmp(type, "ecdh_kdf_md") == 0) {
 469         const EVP_MD *md;
 470         if ((md = EVP_get_digestbyname(value)) == NULL) {
 471             ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_DIGEST);
 472             return 0;
 473         }
 474         return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
 475     } else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
 476         int co_mode;
 477         co_mode = atoi(value);
 478         return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
 479     }
 480
 481     return -2;
 482 }
 483
 484 static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 485 {
 486     EC_KEY *ec = NULL;
 487     EC_PKEY_CTX *dctx = ctx->data;
 488     int ret = 0;
 489     if (dctx->gen_group == NULL) {
 490         ECerr(EC_F_PKEY_EC_PARAMGEN, EC_R_NO_PARAMETERS_SET);
 491         return 0;
 492     }
 493     ec = EC_KEY_new();
 494     if (ec == NULL)
 495         return 0;
 496     ret = EC_KEY_set_group(ec, dctx->gen_group);
 497     if (ret)
 498         EVP_PKEY_assign_EC_KEY(pkey, ec);
 499     else
 500         EC_KEY_free(ec);
 501     return ret;
 502 }
 503
 504 static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 505 {
 506     EC_KEY *ec = NULL;
 507     EC_PKEY_CTX *dctx = ctx->data;
 508     if (ctx->pkey == NULL && dctx->gen_group == NULL) {
 509         ECerr(EC_F_PKEY_EC_KEYGEN, EC_R_NO_PARAMETERS_SET);
 510         return 0;
 511     }
 512     ec = EC_KEY_new();
 513     if (!ec)
 514         return 0;
 515     EVP_PKEY_assign_EC_KEY(pkey, ec);
 516     if (ctx->pkey) {
 517         /* Note: if error return, pkey is freed by parent routine */
 518         if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
 519             return 0;
 520     } else {
 521         if (!EC_KEY_set_group(ec, dctx->gen_group))
 522             return 0;
 523     }
 524     return EC_KEY_generate_key(pkey->pkey.ec);
 525 }
 526
 527 const EVP_PKEY_METHOD ec_pkey_meth = {
 528     EVP_PKEY_EC,
 529     0,
 530     pkey_ec_init,
 531     pkey_ec_copy,
 532     pkey_ec_cleanup,
 533
 534     0,
 535     pkey_ec_paramgen,
 536
 537     0,
 538     pkey_ec_keygen,
 539
 540     0,
 541     pkey_ec_sign,
 542
 543     0,
 544     pkey_ec_verify,
 545
 546     0, 0,
 547
 548     0, 0, 0, 0,
 549
 550     0,
 551     pkey_ecies_encrypt,
 552
 553     0,
 554     pkey_ecies_decrypt,
 555
 556     0,
 557 #ifndef OPENSSL_NO_EC
 558     pkey_ec_kdf_derive,
 559 #else
 560     0,
 561 #endif
 562     pkey_ec_ctrl,
 563     pkey_ec_ctrl_str
 564 };