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     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
 176         if (group == NULL)
 177             return 0;
 178         *keylen = (EC_GROUP_get_degree(group) + 7) / 8;
 179         return 1;
 180     }
 181     pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);
 182
 183     /*
 184      * NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is not
 185      * an error, the result is truncated.
 186      */
 187
 188     outlen = *keylen;
 189
 190     ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
 191     if (ret <= 0)
 192         return 0;
 193     *keylen = ret;
 194     return 1;
 195 }
 196
 197 static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
 198                               unsigned char *key, size_t *keylen)
 199 {
 200     EC_PKEY_CTX *dctx = ctx->data;
 201     unsigned char *ktmp = NULL;
 202     size_t ktmplen;
 203     int rv = 0;
 204     if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
 205         return pkey_ec_derive(ctx, key, keylen);
 206     if (!key) {
 207         *keylen = dctx->kdf_outlen;
 208         return 1;
 209     }
 210     if (*keylen != dctx->kdf_outlen)
 211         return 0;
 212     if (!pkey_ec_derive(ctx, NULL, &ktmplen))
 213         return 0;
 214     if ((ktmp = OPENSSL_malloc(ktmplen)) == NULL) {
 215         ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 216         return 0;
 217     }
 218     if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
 219         goto err;
 220     /* Do KDF stuff */
 221     if (!ossl_ecdh_kdf_X9_63(key, *keylen, ktmp, ktmplen,
 222                              dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md,
 223                              ctx->libctx, ctx->propquery))
 224         goto err;
 225     rv = 1;
 226
 227  err:
 228     OPENSSL_clear_free(ktmp, ktmplen);
 229     return rv;
 230 }
 231 #endif
 232
 233 static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 234 {
 235     EC_PKEY_CTX *dctx = ctx->data;
 236     EC_GROUP *group;
 237     switch (type) {
 238     case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
 239         group = EC_GROUP_new_by_curve_name(p1);
 240         if (group == NULL) {
 241             ERR_raise(ERR_LIB_EC, EC_R_INVALID_CURVE);
 242             return 0;
 243         }
 244         EC_GROUP_free(dctx->gen_group);
 245         dctx->gen_group = group;
 246         return 1;
 247
 248     case EVP_PKEY_CTRL_EC_PARAM_ENC:
 249         if (!dctx->gen_group) {
 250             ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
 251             return 0;
 252         }
 253         EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
 254         return 1;
 255
 256 #ifndef OPENSSL_NO_EC
 257     case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
 258         if (p1 == -2) {
 259             if (dctx->cofactor_mode != -1)
 260                 return dctx->cofactor_mode;
 261             else {
 262                 EC_KEY *ec_key = ctx->pkey->pkey.ec;
 263                 return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
 264             }
 265         } else if (p1 < -1 || p1 > 1)
 266             return -2;
 267         dctx->cofactor_mode = p1;
 268         if (p1 != -1) {
 269             EC_KEY *ec_key = ctx->pkey->pkey.ec;
 270             if (!ec_key->group)
 271                 return -2;
 272             /* If cofactor is 1 cofactor mode does nothing */
 273             if (BN_is_one(ec_key->group->cofactor))
 274                 return 1;
 275             if (!dctx->co_key) {
 276                 dctx->co_key = EC_KEY_dup(ec_key);
 277                 if (!dctx->co_key)
 278                     return 0;
 279             }
 280             if (p1)
 281                 EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
 282             else
 283                 EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
 284         } else {
 285             EC_KEY_free(dctx->co_key);
 286             dctx->co_key = NULL;
 287         }
 288         return 1;
 289 #endif
 290
 291     case EVP_PKEY_CTRL_EC_KDF_TYPE:
 292         if (p1 == -2)
 293             return dctx->kdf_type;
 294         if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_63)
 295             return -2;
 296         dctx->kdf_type = p1;
 297         return 1;
 298
 299     case EVP_PKEY_CTRL_EC_KDF_MD:
 300         dctx->kdf_md = p2;
 301         return 1;
 302
 303     case EVP_PKEY_CTRL_GET_EC_KDF_MD:
 304         *(const EVP_MD **)p2 = dctx->kdf_md;
 305         return 1;
 306
 307     case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
 308         if (p1 <= 0)
 309             return -2;
 310         dctx->kdf_outlen = (size_t)p1;
 311         return 1;
 312
 313     case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
 314         *(int *)p2 = dctx->kdf_outlen;
 315         return 1;
 316
 317     case EVP_PKEY_CTRL_EC_KDF_UKM:
 318         OPENSSL_free(dctx->kdf_ukm);
 319         dctx->kdf_ukm = p2;
 320         if (p2)
 321             dctx->kdf_ukmlen = p1;
 322         else
 323             dctx->kdf_ukmlen = 0;
 324         return 1;
 325
 326     case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
 327         *(unsigned char **)p2 = dctx->kdf_ukm;
 328         return dctx->kdf_ukmlen;
 329
 330     case EVP_PKEY_CTRL_MD:
 331         if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1 &&
 332             EVP_MD_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
 333             EVP_MD_type((const EVP_MD *)p2) != NID_sha224 &&
 334             EVP_MD_type((const EVP_MD *)p2) != NID_sha256 &&
 335             EVP_MD_type((const EVP_MD *)p2) != NID_sha384 &&
 336             EVP_MD_type((const EVP_MD *)p2) != NID_sha512 &&
 337             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_224 &&
 338             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_256 &&
 339             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_384 &&
 340             EVP_MD_type((const EVP_MD *)p2) != NID_sha3_512 &&
 341             EVP_MD_type((const EVP_MD *)p2) != NID_sm3) {
 342             ERR_raise(ERR_LIB_EC, EC_R_INVALID_DIGEST_TYPE);
 343             return 0;
 344         }
 345         dctx->md = p2;
 346         return 1;
 347
 348     case EVP_PKEY_CTRL_GET_MD:
 349         *(const EVP_MD **)p2 = dctx->md;
 350         return 1;
 351
 352     case EVP_PKEY_CTRL_PEER_KEY:
 353         /* Default behaviour is OK */
 354     case EVP_PKEY_CTRL_DIGESTINIT:
 355     case EVP_PKEY_CTRL_PKCS7_SIGN:
 356     case EVP_PKEY_CTRL_CMS_SIGN:
 357         return 1;
 358
 359     default:
 360         return -2;
 361
 362     }
 363 }
 364
 365 static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
 366                             const char *type, const char *value)
 367 {
 368     if (strcmp(type, "ec_paramgen_curve") == 0) {
 369         int nid;
 370         nid = EC_curve_nist2nid(value);
 371         if (nid == NID_undef)
 372             nid = OBJ_sn2nid(value);
 373         if (nid == NID_undef)
 374             nid = OBJ_ln2nid(value);
 375         if (nid == NID_undef) {
 376             ERR_raise(ERR_LIB_EC, EC_R_INVALID_CURVE);
 377             return 0;
 378         }
 379         return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
 380     } else if (strcmp(type, "ec_param_enc") == 0) {
 381         int param_enc;
 382         if (strcmp(value, "explicit") == 0)
 383             param_enc = 0;
 384         else if (strcmp(value, "named_curve") == 0)
 385             param_enc = OPENSSL_EC_NAMED_CURVE;
 386         else
 387             return -2;
 388         return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
 389     } else if (strcmp(type, "ecdh_kdf_md") == 0) {
 390         const EVP_MD *md;
 391         if ((md = EVP_get_digestbyname(value)) == NULL) {
 392             ERR_raise(ERR_LIB_EC, EC_R_INVALID_DIGEST);
 393             return 0;
 394         }
 395         return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
 396     } else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
 397         int co_mode;
 398         co_mode = atoi(value);
 399         return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
 400     }
 401
 402     return -2;
 403 }
 404
 405 static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 406 {
 407     EC_KEY *ec = NULL;
 408     EC_PKEY_CTX *dctx = ctx->data;
 409     int ret;
 410
 411     if (dctx->gen_group == NULL) {
 412         ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
 413         return 0;
 414     }
 415     ec = EC_KEY_new();
 416     if (ec == NULL)
 417         return 0;
 418     if (!(ret = EC_KEY_set_group(ec, dctx->gen_group))
 419         || !ossl_assert(ret = EVP_PKEY_assign_EC_KEY(pkey, ec)))
 420         EC_KEY_free(ec);
 421     return ret;
 422 }
 423
 424 static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 425 {
 426     EC_KEY *ec = NULL;
 427     EC_PKEY_CTX *dctx = ctx->data;
 428     int ret;
 429
 430     if (ctx->pkey == NULL && dctx->gen_group == NULL) {
 431         ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
 432         return 0;
 433     }
 434     ec = EC_KEY_new();
 435     if (ec == NULL)
 436         return 0;
 437     if (!ossl_assert(EVP_PKEY_assign_EC_KEY(pkey, ec))) {
 438         EC_KEY_free(ec);
 439         return 0;
 440     }
 441     /* Note: if error is returned, we count on caller to free pkey->pkey.ec */
 442     if (ctx->pkey != NULL)
 443         ret = EVP_PKEY_copy_parameters(pkey, ctx->pkey);
 444     else
 445         ret = EC_KEY_set_group(ec, dctx->gen_group);
 446
 447     return ret ? EC_KEY_generate_key(ec) : 0;
 448 }
 449
 450 static const EVP_PKEY_METHOD ec_pkey_meth = {
 451     EVP_PKEY_EC,
 452     0,
 453     pkey_ec_init,
 454     pkey_ec_copy,
 455     pkey_ec_cleanup,
 456
 457     0,
 458     pkey_ec_paramgen,
 459
 460     0,
 461     pkey_ec_keygen,
 462
 463     0,
 464     pkey_ec_sign,
 465
 466     0,
 467     pkey_ec_verify,
 468
 469     0, 0,
 470
 471     0, 0, 0, 0,
 472
 473     0,
 474     0,
 475
 476     0,
 477     0,
 478
 479     0,
 480 #ifndef OPENSSL_NO_EC
 481     pkey_ec_kdf_derive,
 482 #else
 483     0,
 484 #endif
 485     pkey_ec_ctrl,
 486     pkey_ec_ctrl_str
 487 };
 488
 489 const EVP_PKEY_METHOD *ossl_ec_pkey_method(void)
 490 {
 491     return &ec_pkey_meth;
 492 }