crypto/ec/ec_pmeth.c

   1 /*
   2  * Copyright 2006-2020 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     EC_PKEY_CTX *dctx = ctx->data;
 165     if (!ctx->pkey || !ctx->peerkey) {
 166         ERR_raise(ERR_LIB_EC, EC_R_KEYS_NOT_SET);
 167         return 0;
 168     }
 169
 170     eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
 171
 172     if (!key) {
 173         const EC_GROUP *group;
 174         group = EC_KEY_get0_group(eckey);
 175         *keylen = (EC_GROUP_get_degree(group) + 7) / 8;
 176         return 1;
 177     }
 178     pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);
 179
 180     /*
 181      * NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is not
 182      * an error, the result is truncated.
 183      */
 184
 185     outlen = *keylen;
 186
 187     ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
 188     if (ret <= 0)
 189         return 0;
 190     *keylen = ret;
 191     return 1;
 192 }
 193
 194 static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
 195                               unsigned char *key, size_t *keylen)
 196 {
 197     EC_PKEY_CTX *dctx = ctx->data;
 198     unsigned char *ktmp = NULL;
 199     size_t ktmplen;
 200     int rv = 0;
 201     if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
 202         return pkey_ec_derive(ctx, key, keylen);
 203     if (!key) {
 204         *keylen = dctx->kdf_outlen;
 205         return 1;
 206     }
 207     if (*keylen != dctx->kdf_outlen)
 208         return 0;
 209     if (!pkey_ec_derive(ctx, NULL, &ktmplen))
 210         return 0;
 211     if ((ktmp = OPENSSL_malloc(ktmplen)) == NULL) {
 212         ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 213         return 0;
 214     }
 215     if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
 216         goto err;
 217     /* Do KDF stuff */
 218     if (!ecdh_KDF_X9_63(key, *keylen, ktmp, ktmplen,
 219                         dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md,
 220                         ctx->libctx, ctx->propquery))
 221         goto err;
 222     rv = 1;
 223
 224  err:
 225     OPENSSL_clear_free(ktmp, ktmplen);
 226     return rv;
 227 }
 228 #endif
 229
 230 static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 231 {
 232     EC_PKEY_CTX *dctx = ctx->data;
 233     EC_GROUP *group;
 234     switch (type) {
 235     case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
 236         group = EC_GROUP_new_by_curve_name(p1);
 237         if (group == NULL) {
 238             ERR_raise(ERR_LIB_EC, EC_R_INVALID_CURVE);
 239             return 0;
 240         }
 241         EC_GROUP_free(dctx->gen_group);
 242         dctx->gen_group = group;
 243         return 1;
 244
 245     case EVP_PKEY_CTRL_EC_PARAM_ENC:
 246         if (!dctx->gen_group) {
 247             ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
 248             return 0;
 249         }
 250         EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
 251         return 1;
 252
 253 #ifndef OPENSSL_NO_EC
 254     case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
 255         if (p1 == -2) {
 256             if (dctx->cofactor_mode != -1)
 257                 return dctx->cofactor_mode;
 258             else {
 259                 EC_KEY *ec_key = ctx->pkey->pkey.ec;
 260                 return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
 261             }
 262         } else if (p1 < -1 || p1 > 1)
 263             return -2;
 264         dctx->cofactor_mode = p1;
 265         if (p1 != -1) {
 266             EC_KEY *ec_key = ctx->pkey->pkey.ec;
 267             if (!ec_key->group)
 268                 return -2;
 269             /* If cofactor is 1 cofactor mode does nothing */
 270             if (BN_is_one(ec_key->group->cofactor))
 271                 return 1;
 272             if (!dctx->co_key) {
 273                 dctx->co_key = EC_KEY_dup(ec_key);
 274                 if (!dctx->co_key)
 275                     return 0;
 276             }
 277             if (p1)
 278                 EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
 279             else
 280                 EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
 281         } else {
 282             EC_KEY_free(dctx->co_key);
 283             dctx->co_key = NULL;
 284         }
 285         return 1;
 286 #endif
 287
 288     case EVP_PKEY_CTRL_EC_KDF_TYPE:
 289         if (p1 == -2)
 290             return dctx->kdf_type;
 291         if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_63)
 292             return -2;
 293         dctx->kdf_type = p1;
 294         return 1;
 295
 296     case EVP_PKEY_CTRL_EC_KDF_MD:
 297         dctx->kdf_md = p2;
 298         return 1;
 299
 300     case EVP_PKEY_CTRL_GET_EC_KDF_MD:
 301         *(const EVP_MD **)p2 = dctx->kdf_md;
 302         return 1;
 303
 304     case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
 305         if (p1 <= 0)
 306             return -2;
 307         dctx->kdf_outlen = (size_t)p1;
 308         return 1;
 309
 310     case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
 311         *(int *)p2 = dctx->kdf_outlen;
 312         return 1;
 313
 314     case EVP_PKEY_CTRL_EC_KDF_UKM:
 315         OPENSSL_free(dctx->kdf_ukm);
 316         dctx->kdf_ukm = p2;
 317         if (p2)
 318             dctx->kdf_ukmlen = p1;
 319         else
 320             dctx->kdf_ukmlen = 0;
 321         return 1;
 322
 323     case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
 324         *(unsigned char **)p2 = dctx->kdf_ukm;
 325         return dctx->kdf_ukmlen;
 326
 327     case EVP_PKEY_CTRL_MD:
 328         if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1 &&
 329             EVP_MD_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
 330             EVP_MD_type((const EVP_MD *)p2) != NID_sha224 &&
 331             EVP_MD_type((const EVP_MD *)p2) != NID_sha256 &&
 332             EVP_MD_type((const EVP_MD *)p2) != NID_sha384 &&
 333             EVP_MD_type((const EVP_MD *)p2) != NID_sha512 &&
 334             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_224 &&
 335             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_256 &&
 336             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_384 &&
 337             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_512 &&
 338             EVP_MD_type((const EVP_MD *)p2) != NID_sm3) {
 339             ERR_raise(ERR_LIB_EC, EC_R_INVALID_DIGEST_TYPE);
 340             return 0;
 341         }
 342         dctx->md = p2;
 343         return 1;
 344
 345     case EVP_PKEY_CTRL_GET_MD:
 346         *(const EVP_MD **)p2 = dctx->md;
 347         return 1;
 348
 349     case EVP_PKEY_CTRL_PEER_KEY:
 350         /* Default behaviour is OK */
 351     case EVP_PKEY_CTRL_DIGESTINIT:
 352     case EVP_PKEY_CTRL_PKCS7_SIGN:
 353     case EVP_PKEY_CTRL_CMS_SIGN:
 354         return 1;
 355
 356     default:
 357         return -2;
 358
 359     }
 360 }
 361
 362 static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
 363                             const char *type, const char *value)
 364 {
 365     if (strcmp(type, "ec_paramgen_curve") == 0) {
 366         int nid;
 367         nid = EC_curve_nist2nid(value);
 368         if (nid == NID_undef)
 369             nid = OBJ_sn2nid(value);
 370         if (nid == NID_undef)
 371             nid = OBJ_ln2nid(value);
 372         if (nid == NID_undef) {
 373             ERR_raise(ERR_LIB_EC, EC_R_INVALID_CURVE);
 374             return 0;
 375         }
 376         return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
 377     } else if (strcmp(type, "ec_param_enc") == 0) {
 378         int param_enc;
 379         if (strcmp(value, "explicit") == 0)
 380             param_enc = 0;
 381         else if (strcmp(value, "named_curve") == 0)
 382             param_enc = OPENSSL_EC_NAMED_CURVE;
 383         else
 384             return -2;
 385         return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
 386     } else if (strcmp(type, "ecdh_kdf_md") == 0) {
 387         const EVP_MD *md;
 388         if ((md = EVP_get_digestbyname(value)) == NULL) {
 389             ERR_raise(ERR_LIB_EC, EC_R_INVALID_DIGEST);
 390             return 0;
 391         }
 392         return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
 393     } else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
 394         int co_mode;
 395         co_mode = atoi(value);
 396         return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
 397     }
 398
 399     return -2;
 400 }
 401
 402 static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 403 {
 404     EC_KEY *ec = NULL;
 405     EC_PKEY_CTX *dctx = ctx->data;
 406     int ret;
 407
 408     if (dctx->gen_group == NULL) {
 409         ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
 410         return 0;
 411     }
 412     ec = EC_KEY_new();
 413     if (ec == NULL)
 414         return 0;
 415     if (!(ret = EC_KEY_set_group(ec, dctx->gen_group))
 416         || !ossl_assert(ret = EVP_PKEY_assign_EC_KEY(pkey, ec)))
 417         EC_KEY_free(ec);
 418     return ret;
 419 }
 420
 421 static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 422 {
 423     EC_KEY *ec = NULL;
 424     EC_PKEY_CTX *dctx = ctx->data;
 425     int ret;
 426
 427     if (ctx->pkey == NULL && dctx->gen_group == NULL) {
 428         ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
 429         return 0;
 430     }
 431     ec = EC_KEY_new();
 432     if (ec == NULL)
 433         return 0;
 434     if (!ossl_assert(EVP_PKEY_assign_EC_KEY(pkey, ec))) {
 435         EC_KEY_free(ec);
 436         return 0;
 437     }
 438     /* Note: if error is returned, we count on caller to free pkey->pkey.ec */
 439     if (ctx->pkey != NULL)
 440         ret = EVP_PKEY_copy_parameters(pkey, ctx->pkey);
 441     else
 442         ret = EC_KEY_set_group(ec, dctx->gen_group);
 443
 444     return ret ? EC_KEY_generate_key(ec) : 0;
 445 }
 446
 447 static const EVP_PKEY_METHOD ec_pkey_meth = {
 448     EVP_PKEY_EC,
 449     0,
 450     pkey_ec_init,
 451     pkey_ec_copy,
 452     pkey_ec_cleanup,
 453
 454     0,
 455     pkey_ec_paramgen,
 456
 457     0,
 458     pkey_ec_keygen,
 459
 460     0,
 461     pkey_ec_sign,
 462
 463     0,
 464     pkey_ec_verify,
 465
 466     0, 0,
 467
 468     0, 0, 0, 0,
 469
 470     0,
 471     0,
 472
 473     0,
 474     0,
 475
 476     0,
 477 #ifndef OPENSSL_NO_EC
 478     pkey_ec_kdf_derive,
 479 #else
 480     0,
 481 #endif
 482     pkey_ec_ctrl,
 483     pkey_ec_ctrl_str
 484 };
 485
 486 const EVP_PKEY_METHOD *ec_pkey_method(void)
 487 {
 488     return &ec_pkey_meth;
 489 }