crypto/ec/ec_pmeth.c

   1 /*
   2  * Copyright 2006-2018 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 #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_local.h"
  16 #include <openssl/evp.h>
  17 #include "crypto/evp.h"
  18
  19 /* EC pkey context structure */
  20
  21 typedef struct {
  22     /* Key and paramgen group */
  23     EC_GROUP *gen_group;
  24     /* message digest */
  25     const EVP_MD *md;
  26     /* Duplicate key if custom cofactor needed */
  27     EC_KEY *co_key;
  28     /* Cofactor mode */
  29     signed char cofactor_mode;
  30     /* KDF (if any) to use for ECDH */
  31     char kdf_type;
  32     /* Message digest to use for key derivation */
  33     const EVP_MD *kdf_md;
  34     /* User key material */
  35     unsigned char *kdf_ukm;
  36     size_t kdf_ukmlen;
  37     /* KDF output length */
  38     size_t kdf_outlen;
  39 } EC_PKEY_CTX;
  40
  41 static int pkey_ec_init(EVP_PKEY_CTX *ctx)
  42 {
  43     EC_PKEY_CTX *dctx;
  44
  45     if ((dctx = OPENSSL_zalloc(sizeof(*dctx))) == NULL) {
  46         ECerr(EC_F_PKEY_EC_INIT, ERR_R_MALLOC_FAILURE);
  47         return 0;
  48     }
  49
  50     dctx->cofactor_mode = -1;
  51     dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
  52     ctx->data = dctx;
  53     return 1;
  54 }
  55
  56 static int pkey_ec_copy(EVP_PKEY_CTX *dst, const EVP_PKEY_CTX *src)
  57 {
  58     EC_PKEY_CTX *dctx, *sctx;
  59     if (!pkey_ec_init(dst))
  60         return 0;
  61     sctx = src->data;
  62     dctx = dst->data;
  63     if (sctx->gen_group) {
  64         dctx->gen_group = EC_GROUP_dup(sctx->gen_group);
  65         if (!dctx->gen_group)
  66             return 0;
  67     }
  68     dctx->md = sctx->md;
  69
  70     if (sctx->co_key) {
  71         dctx->co_key = EC_KEY_dup(sctx->co_key);
  72         if (!dctx->co_key)
  73             return 0;
  74     }
  75     dctx->kdf_type = sctx->kdf_type;
  76     dctx->kdf_md = sctx->kdf_md;
  77     dctx->kdf_outlen = sctx->kdf_outlen;
  78     if (sctx->kdf_ukm) {
  79         dctx->kdf_ukm = OPENSSL_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);
  80         if (!dctx->kdf_ukm)
  81             return 0;
  82     } else
  83         dctx->kdf_ukm = NULL;
  84     dctx->kdf_ukmlen = sctx->kdf_ukmlen;
  85     return 1;
  86 }
  87
  88 static void pkey_ec_cleanup(EVP_PKEY_CTX *ctx)
  89 {
  90     EC_PKEY_CTX *dctx = ctx->data;
  91     if (dctx != NULL) {
  92         EC_GROUP_free(dctx->gen_group);
  93         EC_KEY_free(dctx->co_key);
  94         OPENSSL_free(dctx->kdf_ukm);
  95         OPENSSL_free(dctx);
  96         ctx->data = NULL;
  97     }
  98 }
  99
 100 static int pkey_ec_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
 101                         const unsigned char *tbs, size_t tbslen)
 102 {
 103     int ret, type;
 104     unsigned int sltmp;
 105     EC_PKEY_CTX *dctx = ctx->data;
 106     EC_KEY *ec = ctx->pkey->pkey.ec;
 107     const int sig_sz = ECDSA_size(ec);
 108
 109     /* ensure cast to size_t is safe */
 110     if (!ossl_assert(sig_sz > 0))
 111         return 0;
 112
 113     if (sig == NULL) {
 114         *siglen = (size_t)sig_sz;
 115         return 1;
 116     }
 117
 118     if (*siglen < (size_t)sig_sz) {
 119         ECerr(EC_F_PKEY_EC_SIGN, EC_R_BUFFER_TOO_SMALL);
 120         return 0;
 121     }
 122
 123     type = (dctx->md != NULL) ? EVP_MD_type(dctx->md) : NID_sha1;
 124
 125     ret = ECDSA_sign(type, tbs, tbslen, sig, &sltmp, ec);
 126
 127     if (ret <= 0)
 128         return ret;
 129     *siglen = (size_t)sltmp;
 130     return 1;
 131 }
 132
 133 static int pkey_ec_verify(EVP_PKEY_CTX *ctx,
 134                           const unsigned char *sig, size_t siglen,
 135                           const unsigned char *tbs, size_t tbslen)
 136 {
 137     int ret, type;
 138     EC_PKEY_CTX *dctx = ctx->data;
 139     EC_KEY *ec = ctx->pkey->pkey.ec;
 140
 141     if (dctx->md)
 142         type = EVP_MD_type(dctx->md);
 143     else
 144         type = NID_sha1;
 145
 146     ret = ECDSA_verify(type, tbs, tbslen, sig, siglen, ec);
 147
 148     return ret;
 149 }
 150
 151 #ifndef OPENSSL_NO_EC
 152 static int pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
 153 {
 154     int ret;
 155     size_t outlen;
 156     const EC_POINT *pubkey = NULL;
 157     EC_KEY *eckey;
 158     EC_PKEY_CTX *dctx = ctx->data;
 159     if (!ctx->pkey || !ctx->peerkey) {
 160         ECerr(EC_F_PKEY_EC_DERIVE, EC_R_KEYS_NOT_SET);
 161         return 0;
 162     }
 163
 164     eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
 165
 166     if (!key) {
 167         const EC_GROUP *group;
 168         group = EC_KEY_get0_group(eckey);
 169         *keylen = (EC_GROUP_get_degree(group) + 7) / 8;
 170         return 1;
 171     }
 172     pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);
 173
 174     /*
 175      * NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is not
 176      * an error, the result is truncated.
 177      */
 178
 179     outlen = *keylen;
 180
 181     ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
 182     if (ret <= 0)
 183         return 0;
 184     *keylen = ret;
 185     return 1;
 186 }
 187
 188 static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
 189                               unsigned char *key, size_t *keylen)
 190 {
 191     EC_PKEY_CTX *dctx = ctx->data;
 192     unsigned char *ktmp = NULL;
 193     size_t ktmplen;
 194     int rv = 0;
 195     if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
 196         return pkey_ec_derive(ctx, key, keylen);
 197     if (!key) {
 198         *keylen = dctx->kdf_outlen;
 199         return 1;
 200     }
 201     if (*keylen != dctx->kdf_outlen)
 202         return 0;
 203     if (!pkey_ec_derive(ctx, NULL, &ktmplen))
 204         return 0;
 205     if ((ktmp = OPENSSL_malloc(ktmplen)) == NULL) {
 206         ECerr(EC_F_PKEY_EC_KDF_DERIVE, ERR_R_MALLOC_FAILURE);
 207         return 0;
 208     }
 209     if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
 210         goto err;
 211     /* Do KDF stuff */
 212     if (!ecdh_KDF_X9_63(key, *keylen, ktmp, ktmplen,
 213                         dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md))
 214         goto err;
 215     rv = 1;
 216
 217  err:
 218     OPENSSL_clear_free(ktmp, ktmplen);
 219     return rv;
 220 }
 221 #endif
 222
 223 static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 224 {
 225     EC_PKEY_CTX *dctx = ctx->data;
 226     EC_GROUP *group;
 227     switch (type) {
 228     case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
 229         group = EC_GROUP_new_by_curve_name(p1);
 230         if (group == NULL) {
 231             ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_CURVE);
 232             return 0;
 233         }
 234         EC_GROUP_free(dctx->gen_group);
 235         dctx->gen_group = group;
 236         return 1;
 237
 238     case EVP_PKEY_CTRL_EC_PARAM_ENC:
 239         if (!dctx->gen_group) {
 240             ECerr(EC_F_PKEY_EC_CTRL, EC_R_NO_PARAMETERS_SET);
 241             return 0;
 242         }
 243         EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
 244         return 1;
 245
 246 #ifndef OPENSSL_NO_EC
 247     case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
 248         if (p1 == -2) {
 249             if (dctx->cofactor_mode != -1)
 250                 return dctx->cofactor_mode;
 251             else {
 252                 EC_KEY *ec_key = ctx->pkey->pkey.ec;
 253                 return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
 254             }
 255         } else if (p1 < -1 || p1 > 1)
 256             return -2;
 257         dctx->cofactor_mode = p1;
 258         if (p1 != -1) {
 259             EC_KEY *ec_key = ctx->pkey->pkey.ec;
 260             if (!ec_key->group)
 261                 return -2;
 262             /* If cofactor is 1 cofactor mode does nothing */
 263             if (BN_is_one(ec_key->group->cofactor))
 264                 return 1;
 265             if (!dctx->co_key) {
 266                 dctx->co_key = EC_KEY_dup(ec_key);
 267                 if (!dctx->co_key)
 268                     return 0;
 269             }
 270             if (p1)
 271                 EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
 272             else
 273                 EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
 274         } else {
 275             EC_KEY_free(dctx->co_key);
 276             dctx->co_key = NULL;
 277         }
 278         return 1;
 279 #endif
 280
 281     case EVP_PKEY_CTRL_EC_KDF_TYPE:
 282         if (p1 == -2)
 283             return dctx->kdf_type;
 284         if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_63)
 285             return -2;
 286         dctx->kdf_type = p1;
 287         return 1;
 288
 289     case EVP_PKEY_CTRL_EC_KDF_MD:
 290         dctx->kdf_md = p2;
 291         return 1;
 292
 293     case EVP_PKEY_CTRL_GET_EC_KDF_MD:
 294         *(const EVP_MD **)p2 = dctx->kdf_md;
 295         return 1;
 296
 297     case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
 298         if (p1 <= 0)
 299             return -2;
 300         dctx->kdf_outlen = (size_t)p1;
 301         return 1;
 302
 303     case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
 304         *(int *)p2 = dctx->kdf_outlen;
 305         return 1;
 306
 307     case EVP_PKEY_CTRL_EC_KDF_UKM:
 308         OPENSSL_free(dctx->kdf_ukm);
 309         dctx->kdf_ukm = p2;
 310         if (p2)
 311             dctx->kdf_ukmlen = p1;
 312         else
 313             dctx->kdf_ukmlen = 0;
 314         return 1;
 315
 316     case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
 317         *(unsigned char **)p2 = dctx->kdf_ukm;
 318         return dctx->kdf_ukmlen;
 319
 320     case EVP_PKEY_CTRL_MD:
 321         if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1 &&
 322             EVP_MD_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
 323             EVP_MD_type((const EVP_MD *)p2) != NID_sha224 &&
 324             EVP_MD_type((const EVP_MD *)p2) != NID_sha256 &&
 325             EVP_MD_type((const EVP_MD *)p2) != NID_sha384 &&
 326             EVP_MD_type((const EVP_MD *)p2) != NID_sha512 &&
 327             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_224 &&
 328             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_256 &&
 329             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_384 &&
 330             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_512 &&
 331             EVP_MD_type((const EVP_MD *)p2) != NID_sm3) {
 332             ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_DIGEST_TYPE);
 333             return 0;
 334         }
 335         dctx->md = p2;
 336         return 1;
 337
 338     case EVP_PKEY_CTRL_GET_MD:
 339         *(const EVP_MD **)p2 = dctx->md;
 340         return 1;
 341
 342     case EVP_PKEY_CTRL_PEER_KEY:
 343         /* Default behaviour is OK */
 344     case EVP_PKEY_CTRL_DIGESTINIT:
 345     case EVP_PKEY_CTRL_PKCS7_SIGN:
 346     case EVP_PKEY_CTRL_CMS_SIGN:
 347         return 1;
 348
 349     default:
 350         return -2;
 351
 352     }
 353 }
 354
 355 static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
 356                             const char *type, const char *value)
 357 {
 358     if (strcmp(type, "ec_paramgen_curve") == 0) {
 359         int nid;
 360         nid = EC_curve_nist2nid(value);
 361         if (nid == NID_undef)
 362             nid = OBJ_sn2nid(value);
 363         if (nid == NID_undef)
 364             nid = OBJ_ln2nid(value);
 365         if (nid == NID_undef) {
 366             ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_CURVE);
 367             return 0;
 368         }
 369         return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
 370     } else if (strcmp(type, "ec_param_enc") == 0) {
 371         int param_enc;
 372         if (strcmp(value, "explicit") == 0)
 373             param_enc = 0;
 374         else if (strcmp(value, "named_curve") == 0)
 375             param_enc = OPENSSL_EC_NAMED_CURVE;
 376         else
 377             return -2;
 378         return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
 379     } else if (strcmp(type, "ecdh_kdf_md") == 0) {
 380         const EVP_MD *md;
 381         if ((md = EVP_get_digestbyname(value)) == NULL) {
 382             ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_DIGEST);
 383             return 0;
 384         }
 385         return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
 386     } else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
 387         int co_mode;
 388         co_mode = atoi(value);
 389         return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
 390     }
 391
 392     return -2;
 393 }
 394
 395 static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 396 {
 397     EC_KEY *ec = NULL;
 398     EC_PKEY_CTX *dctx = ctx->data;
 399     int ret;
 400
 401     if (dctx->gen_group == NULL) {
 402         ECerr(EC_F_PKEY_EC_PARAMGEN, EC_R_NO_PARAMETERS_SET);
 403         return 0;
 404     }
 405     ec = EC_KEY_new();
 406     if (ec == NULL)
 407         return 0;
 408     if (!(ret = EC_KEY_set_group(ec, dctx->gen_group))
 409         || !ossl_assert(ret = EVP_PKEY_assign_EC_KEY(pkey, ec)))
 410         EC_KEY_free(ec);
 411     return ret;
 412 }
 413
 414 static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 415 {
 416     EC_KEY *ec = NULL;
 417     EC_PKEY_CTX *dctx = ctx->data;
 418     int ret;
 419
 420     if (ctx->pkey == NULL && dctx->gen_group == NULL) {
 421         ECerr(EC_F_PKEY_EC_KEYGEN, EC_R_NO_PARAMETERS_SET);
 422         return 0;
 423     }
 424     ec = EC_KEY_new();
 425     if (ec == NULL)
 426         return 0;
 427     if (!ossl_assert(EVP_PKEY_assign_EC_KEY(pkey, ec))) {
 428         EC_KEY_free(ec);
 429         return 0;
 430     }
 431     /* Note: if error is returned, we count on caller to free pkey->pkey.ec */
 432     if (ctx->pkey != NULL)
 433         ret = EVP_PKEY_copy_parameters(pkey, ctx->pkey);
 434     else
 435         ret = EC_KEY_set_group(ec, dctx->gen_group);
 436
 437     return ret ? EC_KEY_generate_key(ec) : 0;
 438 }
 439
 440 static const EVP_PKEY_METHOD ec_pkey_meth = {
 441     EVP_PKEY_EC,
 442     0,
 443     pkey_ec_init,
 444     pkey_ec_copy,
 445     pkey_ec_cleanup,
 446
 447     0,
 448     pkey_ec_paramgen,
 449
 450     0,
 451     pkey_ec_keygen,
 452
 453     0,
 454     pkey_ec_sign,
 455
 456     0,
 457     pkey_ec_verify,
 458
 459     0, 0,
 460
 461     0, 0, 0, 0,
 462
 463     0,
 464     0,
 465
 466     0,
 467     0,
 468
 469     0,
 470 #ifndef OPENSSL_NO_EC
 471     pkey_ec_kdf_derive,
 472 #else
 473     0,
 474 #endif
 475     pkey_ec_ctrl,
 476     pkey_ec_ctrl_str
 477 };
 478
 479 const EVP_PKEY_METHOD *ec_pkey_method(void)
 480 {
 481     return &ec_pkey_meth;
 482 }