crypto/ec/ec_pmeth.c

   1 /*
   2  * Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (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 /*
  11  * ECDH and ECDSA low level APIs are deprecated for public use, but still ok
  12  * for internal use.
  13  */
  14 #include "internal/deprecated.h"
  15
  16 #include <stdio.h>
  17 #include "internal/cryptlib.h"
  18 #include <openssl/asn1t.h>
  19 #include <openssl/x509.h>
  20 #include <openssl/ec.h>
  21 #include "ec_local.h"
  22 #include <openssl/evp.h>
  23 #include "crypto/evp.h"
  24
  25 /* EC pkey context structure */
  26
  27 typedef struct {
  28     /* Key and paramgen group */
  29     EC_GROUP *gen_group;
  30     /* message digest */
  31     const EVP_MD *md;
  32     /* Duplicate key if custom cofactor needed */
  33     EC_KEY *co_key;
  34     /* Cofactor mode */
  35     signed char cofactor_mode;
  36     /* KDF (if any) to use for ECDH */
  37     char kdf_type;
  38     /* Message digest to use for key derivation */
  39     const EVP_MD *kdf_md;
  40     /* User key material */
  41     unsigned char *kdf_ukm;
  42     size_t kdf_ukmlen;
  43     /* KDF output length */
  44     size_t kdf_outlen;
  45 } EC_PKEY_CTX;
  46
  47 static int pkey_ec_init(EVP_PKEY_CTX *ctx)
  48 {
  49     EC_PKEY_CTX *dctx;
  50
  51     if ((dctx = OPENSSL_zalloc(sizeof(*dctx))) == NULL) {
  52         ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
  53         return 0;
  54     }
  55
  56     dctx->cofactor_mode = -1;
  57     dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
  58     ctx->data = dctx;
  59     return 1;
  60 }
  61
  62 static int pkey_ec_copy(EVP_PKEY_CTX *dst, const EVP_PKEY_CTX *src)
  63 {
  64     EC_PKEY_CTX *dctx, *sctx;
  65     if (!pkey_ec_init(dst))
  66         return 0;
  67     sctx = src->data;
  68     dctx = dst->data;
  69     if (sctx->gen_group) {
  70         dctx->gen_group = EC_GROUP_dup(sctx->gen_group);
  71         if (!dctx->gen_group)
  72             return 0;
  73     }
  74     dctx->md = sctx->md;
  75
  76     if (sctx->co_key) {
  77         dctx->co_key = EC_KEY_dup(sctx->co_key);
  78         if (!dctx->co_key)
  79             return 0;
  80     }
  81     dctx->kdf_type = sctx->kdf_type;
  82     dctx->kdf_md = sctx->kdf_md;
  83     dctx->kdf_outlen = sctx->kdf_outlen;
  84     if (sctx->kdf_ukm) {
  85         dctx->kdf_ukm = OPENSSL_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);
  86         if (!dctx->kdf_ukm)
  87             return 0;
  88     } else
  89         dctx->kdf_ukm = NULL;
  90     dctx->kdf_ukmlen = sctx->kdf_ukmlen;
  91     return 1;
  92 }
  93
  94 static void pkey_ec_cleanup(EVP_PKEY_CTX *ctx)
  95 {
  96     EC_PKEY_CTX *dctx = ctx->data;
  97     if (dctx != NULL) {
  98         EC_GROUP_free(dctx->gen_group);
  99         EC_KEY_free(dctx->co_key);
 100         OPENSSL_free(dctx->kdf_ukm);
 101         OPENSSL_free(dctx);
 102         ctx->data = NULL;
 103     }
 104 }
 105
 106 static int pkey_ec_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
 107                         const unsigned char *tbs, size_t tbslen)
 108 {
 109     int ret, type;
 110     unsigned int sltmp;
 111     EC_PKEY_CTX *dctx = ctx->data;
 112     EC_KEY *ec = ctx->pkey->pkey.ec;
 113     const int sig_sz = ECDSA_size(ec);
 114
 115     /* ensure cast to size_t is safe */
 116     if (!ossl_assert(sig_sz > 0))
 117         return 0;
 118
 119     if (sig == NULL) {
 120         *siglen = (size_t)sig_sz;
 121         return 1;
 122     }
 123
 124     if (*siglen < (size_t)sig_sz) {
 125         ERR_raise(ERR_LIB_EC, EC_R_BUFFER_TOO_SMALL);
 126         return 0;
 127     }
 128
 129     type = (dctx->md != NULL) ? EVP_MD_type(dctx->md) : NID_sha1;
 130
 131     ret = ECDSA_sign(type, tbs, tbslen, sig, &sltmp, ec);
 132
 133     if (ret <= 0)
 134         return ret;
 135     *siglen = (size_t)sltmp;
 136     return 1;
 137 }
 138
 139 static int pkey_ec_verify(EVP_PKEY_CTX *ctx,
 140                           const unsigned char *sig, size_t siglen,
 141                           const unsigned char *tbs, size_t tbslen)
 142 {
 143     int ret, type;
 144     EC_PKEY_CTX *dctx = ctx->data;
 145     EC_KEY *ec = ctx->pkey->pkey.ec;
 146
 147     if (dctx->md)
 148         type = EVP_MD_type(dctx->md);
 149     else
 150         type = NID_sha1;
 151
 152     ret = ECDSA_verify(type, tbs, tbslen, sig, siglen, ec);
 153
 154     return ret;
 155 }
 156
 157 #ifndef OPENSSL_NO_EC
 158 static int pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
 159 {
 160     int ret;
 161     size_t outlen;
 162     const EC_POINT *pubkey = NULL;
 163     EC_KEY *eckey;
 164     const EC_KEY *eckeypub;
 165     EC_PKEY_CTX *dctx = ctx->data;
 166
 167     if (ctx->pkey == NULL || ctx->peerkey == NULL) {
 168         ERR_raise(ERR_LIB_EC, EC_R_KEYS_NOT_SET);
 169         return 0;
 170     }
 171     eckeypub = EVP_PKEY_get0_EC_KEY(ctx->peerkey);
 172     if (eckeypub == NULL) {
 173         ERR_raise(ERR_LIB_EC, EC_R_KEYS_NOT_SET);
 174         return 0;
 175     }
 176
 177     eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
 178
 179     if (!key) {
 180         const EC_GROUP *group;
 181         group = EC_KEY_get0_group(eckey);
 182
 183         if (group == NULL)
 184             return 0;
 185         *keylen = (EC_GROUP_get_degree(group) + 7) / 8;
 186         return 1;
 187     }
 188     pubkey = EC_KEY_get0_public_key(eckeypub);
 189
 190     /*
 191      * NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is not
 192      * an error, the result is truncated.
 193      */
 194
 195     outlen = *keylen;
 196
 197     ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
 198     if (ret <= 0)
 199         return 0;
 200     *keylen = ret;
 201     return 1;
 202 }
 203
 204 static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
 205                               unsigned char *key, size_t *keylen)
 206 {
 207     EC_PKEY_CTX *dctx = ctx->data;
 208     unsigned char *ktmp = NULL;
 209     size_t ktmplen;
 210     int rv = 0;
 211     if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
 212         return pkey_ec_derive(ctx, key, keylen);
 213     if (!key) {
 214         *keylen = dctx->kdf_outlen;
 215         return 1;
 216     }
 217     if (*keylen != dctx->kdf_outlen)
 218         return 0;
 219     if (!pkey_ec_derive(ctx, NULL, &ktmplen))
 220         return 0;
 221     if ((ktmp = OPENSSL_malloc(ktmplen)) == NULL) {
 222         ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 223         return 0;
 224     }
 225     if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
 226         goto err;
 227     /* Do KDF stuff */
 228     if (!ossl_ecdh_kdf_X9_63(key, *keylen, ktmp, ktmplen,
 229                              dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md,
 230                              ctx->libctx, ctx->propquery))
 231         goto err;
 232     rv = 1;
 233
 234  err:
 235     OPENSSL_clear_free(ktmp, ktmplen);
 236     return rv;
 237 }
 238 #endif
 239
 240 static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 241 {
 242     EC_PKEY_CTX *dctx = ctx->data;
 243     EC_GROUP *group;
 244     switch (type) {
 245     case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
 246         group = EC_GROUP_new_by_curve_name(p1);
 247         if (group == NULL) {
 248             ERR_raise(ERR_LIB_EC, EC_R_INVALID_CURVE);
 249             return 0;
 250         }
 251         EC_GROUP_free(dctx->gen_group);
 252         dctx->gen_group = group;
 253         return 1;
 254
 255     case EVP_PKEY_CTRL_EC_PARAM_ENC:
 256         if (!dctx->gen_group) {
 257             ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
 258             return 0;
 259         }
 260         EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
 261         return 1;
 262
 263 #ifndef OPENSSL_NO_EC
 264     case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
 265         if (p1 == -2) {
 266             if (dctx->cofactor_mode != -1)
 267                 return dctx->cofactor_mode;
 268             else {
 269                 EC_KEY *ec_key = ctx->pkey->pkey.ec;
 270                 return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
 271             }
 272         } else if (p1 < -1 || p1 > 1)
 273             return -2;
 274         dctx->cofactor_mode = p1;
 275         if (p1 != -1) {
 276             EC_KEY *ec_key = ctx->pkey->pkey.ec;
 277             if (!ec_key->group)
 278                 return -2;
 279             /* If cofactor is 1 cofactor mode does nothing */
 280             if (BN_is_one(ec_key->group->cofactor))
 281                 return 1;
 282             if (!dctx->co_key) {
 283                 dctx->co_key = EC_KEY_dup(ec_key);
 284                 if (!dctx->co_key)
 285                     return 0;
 286             }
 287             if (p1)
 288                 EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
 289             else
 290                 EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
 291         } else {
 292             EC_KEY_free(dctx->co_key);
 293             dctx->co_key = NULL;
 294         }
 295         return 1;
 296 #endif
 297
 298     case EVP_PKEY_CTRL_EC_KDF_TYPE:
 299         if (p1 == -2)
 300             return dctx->kdf_type;
 301         if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_63)
 302             return -2;
 303         dctx->kdf_type = p1;
 304         return 1;
 305
 306     case EVP_PKEY_CTRL_EC_KDF_MD:
 307         dctx->kdf_md = p2;
 308         return 1;
 309
 310     case EVP_PKEY_CTRL_GET_EC_KDF_MD:
 311         *(const EVP_MD **)p2 = dctx->kdf_md;
 312         return 1;
 313
 314     case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
 315         if (p1 <= 0)
 316             return -2;
 317         dctx->kdf_outlen = (size_t)p1;
 318         return 1;
 319
 320     case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
 321         *(int *)p2 = dctx->kdf_outlen;
 322         return 1;
 323
 324     case EVP_PKEY_CTRL_EC_KDF_UKM:
 325         OPENSSL_free(dctx->kdf_ukm);
 326         dctx->kdf_ukm = p2;
 327         if (p2)
 328             dctx->kdf_ukmlen = p1;
 329         else
 330             dctx->kdf_ukmlen = 0;
 331         return 1;
 332
 333     case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
 334         *(unsigned char **)p2 = dctx->kdf_ukm;
 335         return dctx->kdf_ukmlen;
 336
 337     case EVP_PKEY_CTRL_MD:
 338         if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1 &&
 339             EVP_MD_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
 340             EVP_MD_type((const EVP_MD *)p2) != NID_sha224 &&
 341             EVP_MD_type((const EVP_MD *)p2) != NID_sha256 &&
 342             EVP_MD_type((const EVP_MD *)p2) != NID_sha384 &&
 343             EVP_MD_type((const EVP_MD *)p2) != NID_sha512 &&
 344             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_224 &&
 345             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_256 &&
 346             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_384 &&
 347             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_512 &&
 348             EVP_MD_type((const EVP_MD *)p2) != NID_sm3) {
 349             ERR_raise(ERR_LIB_EC, EC_R_INVALID_DIGEST_TYPE);
 350             return 0;
 351         }
 352         dctx->md = p2;
 353         return 1;
 354
 355     case EVP_PKEY_CTRL_GET_MD:
 356         *(const EVP_MD **)p2 = dctx->md;
 357         return 1;
 358
 359     case EVP_PKEY_CTRL_PEER_KEY:
 360         /* Default behaviour is OK */
 361     case EVP_PKEY_CTRL_DIGESTINIT:
 362     case EVP_PKEY_CTRL_PKCS7_SIGN:
 363     case EVP_PKEY_CTRL_CMS_SIGN:
 364         return 1;
 365
 366     default:
 367         return -2;
 368
 369     }
 370 }
 371
 372 static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
 373                             const char *type, const char *value)
 374 {
 375     if (strcmp(type, "ec_paramgen_curve") == 0) {
 376         int nid;
 377         nid = EC_curve_nist2nid(value);
 378         if (nid == NID_undef)
 379             nid = OBJ_sn2nid(value);
 380         if (nid == NID_undef)
 381             nid = OBJ_ln2nid(value);
 382         if (nid == NID_undef) {
 383             ERR_raise(ERR_LIB_EC, EC_R_INVALID_CURVE);
 384             return 0;
 385         }
 386         return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
 387     } else if (strcmp(type, "ec_param_enc") == 0) {
 388         int param_enc;
 389         if (strcmp(value, "explicit") == 0)
 390             param_enc = 0;
 391         else if (strcmp(value, "named_curve") == 0)
 392             param_enc = OPENSSL_EC_NAMED_CURVE;
 393         else
 394             return -2;
 395         return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
 396     } else if (strcmp(type, "ecdh_kdf_md") == 0) {
 397         const EVP_MD *md;
 398         if ((md = EVP_get_digestbyname(value)) == NULL) {
 399             ERR_raise(ERR_LIB_EC, EC_R_INVALID_DIGEST);
 400             return 0;
 401         }
 402         return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
 403     } else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
 404         int co_mode;
 405         co_mode = atoi(value);
 406         return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
 407     }
 408
 409     return -2;
 410 }
 411
 412 static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 413 {
 414     EC_KEY *ec = NULL;
 415     EC_PKEY_CTX *dctx = ctx->data;
 416     int ret;
 417
 418     if (dctx->gen_group == NULL) {
 419         ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
 420         return 0;
 421     }
 422     ec = EC_KEY_new();
 423     if (ec == NULL)
 424         return 0;
 425     if (!(ret = EC_KEY_set_group(ec, dctx->gen_group))
 426         || !ossl_assert(ret = EVP_PKEY_assign_EC_KEY(pkey, ec)))
 427         EC_KEY_free(ec);
 428     return ret;
 429 }
 430
 431 static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 432 {
 433     EC_KEY *ec = NULL;
 434     EC_PKEY_CTX *dctx = ctx->data;
 435     int ret;
 436
 437     if (ctx->pkey == NULL && dctx->gen_group == NULL) {
 438         ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
 439         return 0;
 440     }
 441     ec = EC_KEY_new();
 442     if (ec == NULL)
 443         return 0;
 444     if (!ossl_assert(EVP_PKEY_assign_EC_KEY(pkey, ec))) {
 445         EC_KEY_free(ec);
 446         return 0;
 447     }
 448     /* Note: if error is returned, we count on caller to free pkey->pkey.ec */
 449     if (ctx->pkey != NULL)
 450         ret = EVP_PKEY_copy_parameters(pkey, ctx->pkey);
 451     else
 452         ret = EC_KEY_set_group(ec, dctx->gen_group);
 453
 454     return ret ? EC_KEY_generate_key(ec) : 0;
 455 }
 456
 457 static const EVP_PKEY_METHOD ec_pkey_meth = {
 458     EVP_PKEY_EC,
 459     0,
 460     pkey_ec_init,
 461     pkey_ec_copy,
 462     pkey_ec_cleanup,
 463
 464     0,
 465     pkey_ec_paramgen,
 466
 467     0,
 468     pkey_ec_keygen,
 469
 470     0,
 471     pkey_ec_sign,
 472
 473     0,
 474     pkey_ec_verify,
 475
 476     0, 0,
 477
 478     0, 0, 0, 0,
 479
 480     0,
 481     0,
 482
 483     0,
 484     0,
 485
 486     0,
 487 #ifndef OPENSSL_NO_EC
 488     pkey_ec_kdf_derive,
 489 #else
 490     0,
 491 #endif
 492     pkey_ec_ctrl,
 493     pkey_ec_ctrl_str
 494 };
 495
 496 const EVP_PKEY_METHOD *ossl_ec_pkey_method(void)
 497 {
 498     return &ec_pkey_meth;
 499 }