crypto/ec/ec_key.c

   1 /*
   2  * Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
   4  *
   5  * Licensed under the Apache License 2.0 (the "License").  You may not use
   6  * this file except in compliance with the License.  You can obtain a copy
   7  * in the file LICENSE in the source distribution or at
   8  * https://www.openssl.org/source/license.html
   9  */
  10
  11 /*
  12  * ECDSA low level APIs are deprecated for public use, but still ok for
  13  * internal use.
  14  */
  15 #include "internal/deprecated.h"
  16
  17 #include "internal/cryptlib.h"
  18 #include <string.h>
  19 #include "ec_local.h"
  20 #include "internal/refcount.h"
  21 #include <openssl/err.h>
  22 #include <openssl/engine.h>
  23 #include <openssl/self_test.h>
  24 #include "crypto/bn.h"
  25
  26 static int ecdsa_keygen_pairwise_test(EC_KEY *eckey, OSSL_CALLBACK *cb,
  27                                       void *cbarg);
  28
  29 #ifndef FIPS_MODULE
  30 EC_KEY *EC_KEY_new(void)
  31 {
  32     return ec_key_new_method_int(NULL, NULL);
  33 }
  34 #endif
  35
  36 EC_KEY *EC_KEY_new_ex(OPENSSL_CTX *ctx)
  37 {
  38     return ec_key_new_method_int(ctx, NULL);
  39 }
  40
  41 EC_KEY *EC_KEY_new_by_curve_name_ex(OPENSSL_CTX *ctx, int nid)
  42 {
  43     EC_KEY *ret = EC_KEY_new_ex(ctx);
  44     if (ret == NULL)
  45         return NULL;
  46     ret->group = EC_GROUP_new_by_curve_name_ex(ctx, nid);
  47     if (ret->group == NULL) {
  48         EC_KEY_free(ret);
  49         return NULL;
  50     }
  51     if (ret->meth->set_group != NULL
  52         && ret->meth->set_group(ret, ret->group) == 0) {
  53         EC_KEY_free(ret);
  54         return NULL;
  55     }
  56     return ret;
  57 }
  58
  59 #ifndef FIPS_MODULE
  60 EC_KEY *EC_KEY_new_by_curve_name(int nid)
  61 {
  62     return EC_KEY_new_by_curve_name_ex(NULL, nid);
  63 }
  64 #endif
  65
  66 void EC_KEY_free(EC_KEY *r)
  67 {
  68     int i;
  69
  70     if (r == NULL)
  71         return;
  72
  73     CRYPTO_DOWN_REF(&r->references, &i, r->lock);
  74     REF_PRINT_COUNT("EC_KEY", r);
  75     if (i > 0)
  76         return;
  77     REF_ASSERT_ISNT(i < 0);
  78
  79     if (r->meth != NULL && r->meth->finish != NULL)
  80         r->meth->finish(r);
  81
  82 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODULE)
  83     ENGINE_finish(r->engine);
  84 #endif
  85
  86     if (r->group && r->group->meth->keyfinish)
  87         r->group->meth->keyfinish(r);
  88
  89 #ifndef FIPS_MODULE
  90     CRYPTO_free_ex_data(CRYPTO_EX_INDEX_EC_KEY, r, &r->ex_data);
  91 #endif
  92     CRYPTO_THREAD_lock_free(r->lock);
  93     EC_GROUP_free(r->group);
  94     EC_POINT_free(r->pub_key);
  95     BN_clear_free(r->priv_key);
  96
  97     OPENSSL_clear_free((void *)r, sizeof(EC_KEY));
  98 }
  99
 100 EC_KEY *EC_KEY_copy(EC_KEY *dest, const EC_KEY *src)
 101 {
 102     if (dest == NULL || src == NULL) {
 103         ECerr(EC_F_EC_KEY_COPY, ERR_R_PASSED_NULL_PARAMETER);
 104         return NULL;
 105     }
 106     if (src->meth != dest->meth) {
 107         if (dest->meth->finish != NULL)
 108             dest->meth->finish(dest);
 109         if (dest->group && dest->group->meth->keyfinish)
 110             dest->group->meth->keyfinish(dest);
 111 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODULE)
 112         if (ENGINE_finish(dest->engine) == 0)
 113             return 0;
 114         dest->engine = NULL;
 115 #endif
 116     }
 117     dest->libctx = src->libctx;
 118     /* copy the parameters */
 119     if (src->group != NULL) {
 120         const EC_METHOD *meth = EC_GROUP_method_of(src->group);
 121         /* clear the old group */
 122         EC_GROUP_free(dest->group);
 123         dest->group = EC_GROUP_new_ex(src->libctx, meth);
 124         if (dest->group == NULL)
 125             return NULL;
 126         if (!EC_GROUP_copy(dest->group, src->group))
 127             return NULL;
 128
 129         /*  copy the public key */
 130         if (src->pub_key != NULL) {
 131             EC_POINT_free(dest->pub_key);
 132             dest->pub_key = EC_POINT_new(src->group);
 133             if (dest->pub_key == NULL)
 134                 return NULL;
 135             if (!EC_POINT_copy(dest->pub_key, src->pub_key))
 136                 return NULL;
 137         }
 138         /* copy the private key */
 139         if (src->priv_key != NULL) {
 140             if (dest->priv_key == NULL) {
 141                 dest->priv_key = BN_new();
 142                 if (dest->priv_key == NULL)
 143                     return NULL;
 144             }
 145             if (!BN_copy(dest->priv_key, src->priv_key))
 146                 return NULL;
 147             if (src->group->meth->keycopy
 148                 && src->group->meth->keycopy(dest, src) == 0)
 149                 return NULL;
 150         }
 151     }
 152
 153
 154     /* copy the rest */
 155     dest->enc_flag = src->enc_flag;
 156     dest->conv_form = src->conv_form;
 157     dest->version = src->version;
 158     dest->flags = src->flags;
 159 #ifndef FIPS_MODULE
 160     if (!CRYPTO_dup_ex_data(CRYPTO_EX_INDEX_EC_KEY,
 161                             &dest->ex_data, &src->ex_data))
 162         return NULL;
 163 #endif
 164
 165     if (src->meth != dest->meth) {
 166 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODULE)
 167         if (src->engine != NULL && ENGINE_init(src->engine) == 0)
 168             return NULL;
 169         dest->engine = src->engine;
 170 #endif
 171         dest->meth = src->meth;
 172     }
 173
 174     if (src->meth->copy != NULL && src->meth->copy(dest, src) == 0)
 175         return NULL;
 176
 177     dest->dirty_cnt++;
 178
 179     return dest;
 180 }
 181
 182 EC_KEY *EC_KEY_dup(const EC_KEY *ec_key)
 183 {
 184     EC_KEY *ret = ec_key_new_method_int(ec_key->libctx, ec_key->engine);
 185
 186     if (ret == NULL)
 187         return NULL;
 188
 189     if (EC_KEY_copy(ret, ec_key) == NULL) {
 190         EC_KEY_free(ret);
 191         return NULL;
 192     }
 193     return ret;
 194 }
 195
 196 int EC_KEY_up_ref(EC_KEY *r)
 197 {
 198     int i;
 199
 200     if (CRYPTO_UP_REF(&r->references, &i, r->lock) <= 0)
 201         return 0;
 202
 203     REF_PRINT_COUNT("EC_KEY", r);
 204     REF_ASSERT_ISNT(i < 2);
 205     return ((i > 1) ? 1 : 0);
 206 }
 207
 208 ENGINE *EC_KEY_get0_engine(const EC_KEY *eckey)
 209 {
 210     return eckey->engine;
 211 }
 212
 213 int EC_KEY_generate_key(EC_KEY *eckey)
 214 {
 215     if (eckey == NULL || eckey->group == NULL) {
 216         ECerr(EC_F_EC_KEY_GENERATE_KEY, ERR_R_PASSED_NULL_PARAMETER);
 217         return 0;
 218     }
 219     if (eckey->meth->keygen != NULL) {
 220         int ret;
 221
 222         ret = eckey->meth->keygen(eckey);
 223         if (ret == 1)
 224             eckey->dirty_cnt++;
 225
 226         return ret;
 227     }
 228     ECerr(EC_F_EC_KEY_GENERATE_KEY, EC_R_OPERATION_NOT_SUPPORTED);
 229     return 0;
 230 }
 231
 232 int ossl_ec_key_gen(EC_KEY *eckey)
 233 {
 234     int ret;
 235
 236     ret = eckey->group->meth->keygen(eckey);
 237
 238     if (ret == 1)
 239         eckey->dirty_cnt++;
 240     return ret;
 241 }
 242
 243 /*
 244  * ECC Key generation.
 245  * See SP800-56AR3 5.6.1.2.2 "Key Pair Generation by Testing Candidates"
 246  *
 247  * Params:
 248  *     libctx A context containing an optional self test callback.
 249  *     eckey An EC key object that contains domain params. The generated keypair
 250  *           is stored in this object.
 251  *     pairwise_test Set to non zero to perform a pairwise test. If the test
 252  *                   fails then the keypair is not generated,
 253  * Returns 1 if the keypair was generated or 0 otherwise.
 254  */
 255 int ec_generate_key(OPENSSL_CTX *libctx, EC_KEY *eckey, int pairwise_test)
 256 {
 257     int ok = 0;
 258     BIGNUM *priv_key = NULL;
 259     const BIGNUM *order = NULL;
 260     EC_POINT *pub_key = NULL;
 261     const EC_GROUP *group = eckey->group;
 262     BN_CTX *ctx = BN_CTX_secure_new_ex(eckey->libctx);
 263
 264     if (ctx == NULL)
 265         goto err;
 266
 267     if (eckey->priv_key == NULL) {
 268         priv_key = BN_secure_new();
 269         if (priv_key == NULL)
 270             goto err;
 271     } else
 272         priv_key = eckey->priv_key;
 273
 274     /*
 275      * Steps (1-2): Check domain parameters and security strength.
 276      * These steps must be done by the user. This would need to be
 277      * stated in the security policy.
 278      */
 279
 280     order = EC_GROUP_get0_order(group);
 281     if (order == NULL)
 282         goto err;
 283
 284     /*
 285      * Steps (3-7): priv_key = DRBG_RAND(order_n_bits) (range [1, n-1]).
 286      * Although this is slightly different from the standard, it is effectively
 287      * equivalent as it gives an unbiased result ranging from 1..n-1. It is also
 288      * faster as the standard needs to retry more often. Also doing
 289      * 1 + rand[0..n-2] would effect the way that tests feed dummy entropy into
 290      * rand so the simpler backward compatible method has been used here.
 291      */
 292     do
 293         if (!BN_priv_rand_range_ex(priv_key, order, ctx))
 294             goto err;
 295     while (BN_is_zero(priv_key)) ;
 296
 297     if (eckey->pub_key == NULL) {
 298         pub_key = EC_POINT_new(group);
 299         if (pub_key == NULL)
 300             goto err;
 301     } else
 302         pub_key = eckey->pub_key;
 303
 304     /* Step (8) : pub_key = priv_key * G (where G is a point on the curve) */
 305     if (!EC_POINT_mul(group, pub_key, priv_key, NULL, NULL, ctx))
 306         goto err;
 307
 308     eckey->priv_key = priv_key;
 309     eckey->pub_key = pub_key;
 310     priv_key = NULL;
 311     pub_key = NULL;
 312
 313     eckey->dirty_cnt++;
 314
 315 #ifdef FIPS_MODULE
 316     pairwise_test = 1;
 317 #endif /* FIPS_MODULE */
 318
 319     ok = 1;
 320     if (pairwise_test) {
 321         OSSL_CALLBACK *cb = NULL;
 322         void *cbarg = NULL;
 323
 324         OSSL_SELF_TEST_get_callback(libctx, &cb, &cbarg);
 325         ok = ecdsa_keygen_pairwise_test(eckey, cb, cbarg);
 326     }
 327 err:
 328     /* Step (9): If there is an error return an invalid keypair. */
 329     if (!ok) {
 330         BN_clear(eckey->priv_key);
 331         if (eckey->pub_key != NULL)
 332             EC_POINT_set_to_infinity(group, eckey->pub_key);
 333     }
 334
 335     EC_POINT_free(pub_key);
 336     BN_clear_free(priv_key);
 337     BN_CTX_free(ctx);
 338     return ok;
 339 }
 340
 341 int ec_key_simple_generate_key(EC_KEY *eckey)
 342 {
 343     return ec_generate_key(NULL, eckey, 0);
 344 }
 345
 346 int ec_key_simple_generate_public_key(EC_KEY *eckey)
 347 {
 348     int ret;
 349
 350     /*
 351      * See SP800-56AR3 5.6.1.2.2: Step (8)
 352      * pub_key = priv_key * G (where G is a point on the curve)
 353      */
 354     ret = EC_POINT_mul(eckey->group, eckey->pub_key, eckey->priv_key, NULL,
 355                        NULL, NULL);
 356
 357     if (ret == 1)
 358         eckey->dirty_cnt++;
 359
 360     return ret;
 361 }
 362
 363 int EC_KEY_check_key(const EC_KEY *eckey)
 364 {
 365     if (eckey == NULL || eckey->group == NULL || eckey->pub_key == NULL) {
 366         ECerr(EC_F_EC_KEY_CHECK_KEY, ERR_R_PASSED_NULL_PARAMETER);
 367         return 0;
 368     }
 369
 370     if (eckey->group->meth->keycheck == NULL) {
 371         ECerr(EC_F_EC_KEY_CHECK_KEY, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
 372         return 0;
 373     }
 374
 375     return eckey->group->meth->keycheck(eckey);
 376 }
 377
 378 /*
 379  * Check the range of the EC public key.
 380  * See SP800-56A R3 Section 5.6.2.3.3 (Part 2)
 381  * i.e.
 382  *  - If q = odd prime p: Verify that xQ and yQ are integers in the
 383  *    interval[0, p - 1], OR
 384  *  - If q = 2m: Verify that xQ and yQ are bit strings of length m bits.
 385  * Returns 1 if the public key has a valid range, otherwise it returns 0.
 386  */
 387 static int ec_key_public_range_check(BN_CTX *ctx, const EC_KEY *key)
 388 {
 389     int ret = 0;
 390     BIGNUM *x, *y;
 391
 392     BN_CTX_start(ctx);
 393     x = BN_CTX_get(ctx);
 394     y = BN_CTX_get(ctx);
 395     if (y == NULL)
 396         goto err;
 397
 398     if (!EC_POINT_get_affine_coordinates(key->group, key->pub_key, x, y, ctx))
 399         goto err;
 400
 401     if (EC_METHOD_get_field_type(key->group->meth) == NID_X9_62_prime_field) {
 402         if (BN_is_negative(x)
 403             || BN_cmp(x, key->group->field) >= 0
 404             || BN_is_negative(y)
 405             || BN_cmp(y, key->group->field) >= 0) {
 406             goto err;
 407         }
 408     } else {
 409         int m = EC_GROUP_get_degree(key->group);
 410         if (BN_num_bits(x) > m || BN_num_bits(y) > m) {
 411             goto err;
 412         }
 413     }
 414     ret = 1;
 415 err:
 416     BN_CTX_end(ctx);
 417     return ret;
 418 }
 419
 420 /*
 421  * ECC Key validation as specified in SP800-56A R3.
 422  * Section 5.6.2.3.3 ECC Full Public-Key Validation.
 423  */
 424 int ec_key_public_check(const EC_KEY *eckey, BN_CTX *ctx)
 425 {
 426     int ret = 0;
 427     EC_POINT *point = NULL;
 428     const BIGNUM *order = NULL;
 429
 430     if (eckey == NULL || eckey->group == NULL || eckey->pub_key == NULL) {
 431         ECerr(0, ERR_R_PASSED_NULL_PARAMETER);
 432         return 0;
 433     }
 434
 435     /* 5.6.2.3.3 (Step 1): Q != infinity */
 436     if (EC_POINT_is_at_infinity(eckey->group, eckey->pub_key)) {
 437         ECerr(0, EC_R_POINT_AT_INFINITY);
 438         return 0;
 439     }
 440
 441     point = EC_POINT_new(eckey->group);
 442     if (point == NULL)
 443         return 0;
 444
 445     /* 5.6.2.3.3 (Step 2) Test if the public key is in range */
 446     if (!ec_key_public_range_check(ctx, eckey)) {
 447         ECerr(0, EC_R_COORDINATES_OUT_OF_RANGE);
 448         goto err;
 449     }
 450
 451     /* 5.6.2.3.3 (Step 3) is the pub_key on the elliptic curve */
 452     if (EC_POINT_is_on_curve(eckey->group, eckey->pub_key, ctx) <= 0) {
 453         ECerr(0, EC_R_POINT_IS_NOT_ON_CURVE);
 454         goto err;
 455     }
 456
 457     order = eckey->group->order;
 458     if (BN_is_zero(order)) {
 459         ECerr(0, EC_R_INVALID_GROUP_ORDER);
 460         goto err;
 461     }
 462     /* 5.6.2.3.3 (Step 4) : pub_key * order is the point at infinity. */
 463     if (!EC_POINT_mul(eckey->group, point, NULL, eckey->pub_key, order, ctx)) {
 464         ECerr(0, ERR_R_EC_LIB);
 465         goto err;
 466     }
 467     if (!EC_POINT_is_at_infinity(eckey->group, point)) {
 468         ECerr(0, EC_R_WRONG_ORDER);
 469         goto err;
 470     }
 471     ret = 1;
 472 err:
 473     EC_POINT_free(point);
 474     return ret;
 475 }
 476
 477 /*
 478  * ECC Key validation as specified in SP800-56A R3.
 479  * Section 5.6.2.1.2 Owner Assurance of Private-Key Validity
 480  * The private key is in the range [1, order-1]
 481  */
 482 int ec_key_private_check(const EC_KEY *eckey)
 483 {
 484     if (eckey == NULL || eckey->group == NULL || eckey->priv_key == NULL) {
 485         ECerr(0, ERR_R_PASSED_NULL_PARAMETER);
 486         return 0;
 487     }
 488     if (BN_cmp(eckey->priv_key, BN_value_one()) < 0
 489         || BN_cmp(eckey->priv_key, eckey->group->order) >= 0) {
 490         ECerr(0, EC_R_INVALID_PRIVATE_KEY);
 491         return 0;
 492     }
 493     return 1;
 494 }
 495
 496 /*
 497  * ECC Key validation as specified in SP800-56A R3.
 498  * Section 5.6.2.1.4 Owner Assurance of Pair-wise Consistency (b)
 499  * Check if generator * priv_key = pub_key
 500  */
 501 int ec_key_pairwise_check(const EC_KEY *eckey, BN_CTX *ctx)
 502 {
 503     int ret = 0;
 504     EC_POINT *point = NULL;
 505
 506     if (eckey == NULL
 507        || eckey->group == NULL
 508        || eckey->pub_key == NULL
 509        || eckey->priv_key == NULL) {
 510         ECerr(0, ERR_R_PASSED_NULL_PARAMETER);
 511         return 0;
 512     }
 513
 514     point = EC_POINT_new(eckey->group);
 515     if (point == NULL)
 516         goto err;
 517
 518
 519     if (!EC_POINT_mul(eckey->group, point, eckey->priv_key, NULL, NULL, ctx)) {
 520         ECerr(0, ERR_R_EC_LIB);
 521         goto err;
 522     }
 523     if (EC_POINT_cmp(eckey->group, point, eckey->pub_key, ctx) != 0) {
 524         ECerr(0, EC_R_INVALID_PRIVATE_KEY);
 525         goto err;
 526     }
 527     ret = 1;
 528 err:
 529     EC_POINT_free(point);
 530     return ret;
 531 }
 532
 533
 534 /*
 535  * ECC Key validation as specified in SP800-56A R3.
 536  *    Section 5.6.2.3.3 ECC Full Public-Key Validation
 537  *    Section 5.6.2.1.2 Owner Assurance of Private-Key Validity
 538  *    Section 5.6.2.1.4 Owner Assurance of Pair-wise Consistency
 539  * NOTES:
 540  *    Before calling this method in fips mode, there should be an assurance that
 541  *    an approved elliptic-curve group is used.
 542  * Returns 1 if the key is valid, otherwise it returns 0.
 543  */
 544 int ec_key_simple_check_key(const EC_KEY *eckey)
 545 {
 546     int ok = 0;
 547     BN_CTX *ctx = NULL;
 548
 549     if (eckey == NULL) {
 550         ECerr(0, ERR_R_PASSED_NULL_PARAMETER);
 551         return 0;
 552     }
 553     if ((ctx = BN_CTX_new_ex(eckey->libctx)) == NULL)
 554         return 0;
 555
 556     if (!ec_key_public_check(eckey, ctx))
 557         goto err;
 558
 559     if (eckey->priv_key != NULL) {
 560         if (!ec_key_private_check(eckey)
 561             || !ec_key_pairwise_check(eckey, ctx))
 562             goto err;
 563     }
 564     ok = 1;
 565 err:
 566     BN_CTX_free(ctx);
 567     return ok;
 568 }
 569
 570 int EC_KEY_set_public_key_affine_coordinates(EC_KEY *key, BIGNUM *x,
 571                                              BIGNUM *y)
 572 {
 573     BN_CTX *ctx = NULL;
 574     BIGNUM *tx, *ty;
 575     EC_POINT *point = NULL;
 576     int ok = 0;
 577
 578     if (key == NULL || key->group == NULL || x == NULL || y == NULL) {
 579         ECerr(EC_F_EC_KEY_SET_PUBLIC_KEY_AFFINE_COORDINATES,
 580               ERR_R_PASSED_NULL_PARAMETER);
 581         return 0;
 582     }
 583     ctx = BN_CTX_new_ex(key->libctx);
 584     if (ctx == NULL)
 585         return 0;
 586
 587     BN_CTX_start(ctx);
 588     point = EC_POINT_new(key->group);
 589
 590     if (point == NULL)
 591         goto err;
 592
 593     tx = BN_CTX_get(ctx);
 594     ty = BN_CTX_get(ctx);
 595     if (ty == NULL)
 596         goto err;
 597
 598     if (!EC_POINT_set_affine_coordinates(key->group, point, x, y, ctx))
 599         goto err;
 600     if (!EC_POINT_get_affine_coordinates(key->group, point, tx, ty, ctx))
 601         goto err;
 602
 603     /*
 604      * Check if retrieved coordinates match originals. The range check is done
 605      * inside EC_KEY_check_key().
 606      */
 607     if (BN_cmp(x, tx) || BN_cmp(y, ty)) {
 608         ECerr(EC_F_EC_KEY_SET_PUBLIC_KEY_AFFINE_COORDINATES,
 609               EC_R_COORDINATES_OUT_OF_RANGE);
 610         goto err;
 611     }
 612
 613     /* EC_KEY_set_public_key updates dirty_cnt */
 614     if (!EC_KEY_set_public_key(key, point))
 615         goto err;
 616
 617     if (EC_KEY_check_key(key) == 0)
 618         goto err;
 619
 620     ok = 1;
 621
 622  err:
 623     BN_CTX_end(ctx);
 624     BN_CTX_free(ctx);
 625     EC_POINT_free(point);
 626     return ok;
 627
 628 }
 629
 630 OPENSSL_CTX *ec_key_get_libctx(const EC_KEY *key)
 631 {
 632     return key->libctx;
 633 }
 634
 635 const EC_GROUP *EC_KEY_get0_group(const EC_KEY *key)
 636 {
 637     return key->group;
 638 }
 639
 640 int EC_KEY_set_group(EC_KEY *key, const EC_GROUP *group)
 641 {
 642     if (key->meth->set_group != NULL && key->meth->set_group(key, group) == 0)
 643         return 0;
 644     EC_GROUP_free(key->group);
 645     key->group = EC_GROUP_dup(group);
 646     key->dirty_cnt++;
 647     return (key->group == NULL) ? 0 : 1;
 648 }
 649
 650 const BIGNUM *EC_KEY_get0_private_key(const EC_KEY *key)
 651 {
 652     return key->priv_key;
 653 }
 654
 655 int EC_KEY_set_private_key(EC_KEY *key, const BIGNUM *priv_key)
 656 {
 657     int fixed_top;
 658     const BIGNUM *order = NULL;
 659     BIGNUM *tmp_key = NULL;
 660
 661     if (key->group == NULL || key->group->meth == NULL)
 662         return 0;
 663
 664     /*
 665      * Not only should key->group be set, but it should also be in a valid
 666      * fully initialized state.
 667      *
 668      * Specifically, to operate in constant time, we need that the group order
 669      * is set, as we use its length as the fixed public size of any scalar used
 670      * as an EC private key.
 671      */
 672     order = EC_GROUP_get0_order(key->group);
 673     if (order == NULL || BN_is_zero(order))
 674         return 0; /* This should never happen */
 675
 676     if (key->group->meth->set_private != NULL
 677         && key->group->meth->set_private(key, priv_key) == 0)
 678         return 0;
 679     if (key->meth->set_private != NULL
 680         && key->meth->set_private(key, priv_key) == 0)
 681         return 0;
 682
 683     /*
 684      * We should never leak the bit length of the secret scalar in the key,
 685      * so we always set the `BN_FLG_CONSTTIME` flag on the internal `BIGNUM`
 686      * holding the secret scalar.
 687      *
 688      * This is important also because `BN_dup()` (and `BN_copy()`) do not
 689      * propagate the `BN_FLG_CONSTTIME` flag from the source `BIGNUM`, and
 690      * this brings an extra risk of inadvertently losing the flag, even when
 691      * the caller specifically set it.
 692      *
 693      * The propagation has been turned on and off a few times in the past
 694      * years because in some conditions has shown unintended consequences in
 695      * some code paths, so at the moment we can't fix this in the BN layer.
 696      *
 697      * In `EC_KEY_set_private_key()` we can work around the propagation by
 698      * manually setting the flag after `BN_dup()` as we know for sure that
 699      * inside the EC module the `BN_FLG_CONSTTIME` is always treated
 700      * correctly and should not generate unintended consequences.
 701      *
 702      * Setting the BN_FLG_CONSTTIME flag alone is never enough, we also have
 703      * to preallocate the BIGNUM internal buffer to a fixed public size big
 704      * enough that operations performed during the processing never trigger
 705      * a realloc which would leak the size of the scalar through memory
 706      * accesses.
 707      *
 708      * Fixed Length
 709      * ------------
 710      *
 711      * The order of the large prime subgroup of the curve is our choice for
 712      * a fixed public size, as that is generally the upper bound for
 713      * generating a private key in EC cryptosystems and should fit all valid
 714      * secret scalars.
 715      *
 716      * For preallocating the BIGNUM storage we look at the number of "words"
 717      * required for the internal representation of the order, and we
 718      * preallocate 2 extra "words" in case any of the subsequent processing
 719      * might temporarily overflow the order length.
 720      */
 721     tmp_key = BN_dup(priv_key);
 722     if (tmp_key == NULL)
 723         return 0;
 724
 725     BN_set_flags(tmp_key, BN_FLG_CONSTTIME);
 726
 727     fixed_top = bn_get_top(order) + 2;
 728     if (bn_wexpand(tmp_key, fixed_top) == NULL) {
 729         BN_clear_free(tmp_key);
 730         return 0;
 731     }
 732
 733     BN_clear_free(key->priv_key);
 734     key->priv_key = tmp_key;
 735     key->dirty_cnt++;
 736
 737     return 1;
 738 }
 739
 740 const EC_POINT *EC_KEY_get0_public_key(const EC_KEY *key)
 741 {
 742     return key->pub_key;
 743 }
 744
 745 int EC_KEY_set_public_key(EC_KEY *key, const EC_POINT *pub_key)
 746 {
 747     if (key->meth->set_public != NULL
 748         && key->meth->set_public(key, pub_key) == 0)
 749         return 0;
 750     EC_POINT_free(key->pub_key);
 751     key->pub_key = EC_POINT_dup(pub_key, key->group);
 752     key->dirty_cnt++;
 753     return (key->pub_key == NULL) ? 0 : 1;
 754 }
 755
 756 unsigned int EC_KEY_get_enc_flags(const EC_KEY *key)
 757 {
 758     return key->enc_flag;
 759 }
 760
 761 void EC_KEY_set_enc_flags(EC_KEY *key, unsigned int flags)
 762 {
 763     key->enc_flag = flags;
 764 }
 765
 766 point_conversion_form_t EC_KEY_get_conv_form(const EC_KEY *key)
 767 {
 768     return key->conv_form;
 769 }
 770
 771 void EC_KEY_set_conv_form(EC_KEY *key, point_conversion_form_t cform)
 772 {
 773     key->conv_form = cform;
 774     if (key->group != NULL)
 775         EC_GROUP_set_point_conversion_form(key->group, cform);
 776 }
 777
 778 void EC_KEY_set_asn1_flag(EC_KEY *key, int flag)
 779 {
 780     if (key->group != NULL)
 781         EC_GROUP_set_asn1_flag(key->group, flag);
 782 }
 783
 784 #ifndef OPENSSL_NO_DEPRECATED_3_0
 785 int EC_KEY_precompute_mult(EC_KEY *key, BN_CTX *ctx)
 786 {
 787     if (key->group == NULL)
 788         return 0;
 789     return EC_GROUP_precompute_mult(key->group, ctx);
 790 }
 791 #endif
 792
 793 int EC_KEY_get_flags(const EC_KEY *key)
 794 {
 795     return key->flags;
 796 }
 797
 798 void EC_KEY_set_flags(EC_KEY *key, int flags)
 799 {
 800     key->flags |= flags;
 801     key->dirty_cnt++;
 802 }
 803
 804 void EC_KEY_clear_flags(EC_KEY *key, int flags)
 805 {
 806     key->flags &= ~flags;
 807     key->dirty_cnt++;
 808 }
 809
 810 size_t EC_KEY_key2buf(const EC_KEY *key, point_conversion_form_t form,
 811                         unsigned char **pbuf, BN_CTX *ctx)
 812 {
 813     if (key == NULL || key->pub_key == NULL || key->group == NULL)
 814         return 0;
 815     return EC_POINT_point2buf(key->group, key->pub_key, form, pbuf, ctx);
 816 }
 817
 818 int EC_KEY_oct2key(EC_KEY *key, const unsigned char *buf, size_t len,
 819                    BN_CTX *ctx)
 820 {
 821     if (key == NULL || key->group == NULL)
 822         return 0;
 823     if (key->pub_key == NULL)
 824         key->pub_key = EC_POINT_new(key->group);
 825     if (key->pub_key == NULL)
 826         return 0;
 827     if (EC_POINT_oct2point(key->group, key->pub_key, buf, len, ctx) == 0)
 828         return 0;
 829     key->dirty_cnt++;
 830     /*
 831      * Save the point conversion form.
 832      * For non-custom curves the first octet of the buffer (excluding
 833      * the last significant bit) contains the point conversion form.
 834      * EC_POINT_oct2point() has already performed sanity checking of
 835      * the buffer so we know it is valid.
 836      */
 837     if ((key->group->meth->flags & EC_FLAGS_CUSTOM_CURVE) == 0)
 838         key->conv_form = (point_conversion_form_t)(buf[0] & ~0x01);
 839     return 1;
 840 }
 841
 842 size_t EC_KEY_priv2oct(const EC_KEY *eckey,
 843                        unsigned char *buf, size_t len)
 844 {
 845     if (eckey->group == NULL || eckey->group->meth == NULL)
 846         return 0;
 847     if (eckey->group->meth->priv2oct == NULL) {
 848         ECerr(EC_F_EC_KEY_PRIV2OCT, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
 849         return 0;
 850     }
 851
 852     return eckey->group->meth->priv2oct(eckey, buf, len);
 853 }
 854
 855 size_t ec_key_simple_priv2oct(const EC_KEY *eckey,
 856                               unsigned char *buf, size_t len)
 857 {
 858     size_t buf_len;
 859
 860     buf_len = (EC_GROUP_order_bits(eckey->group) + 7) / 8;
 861     if (eckey->priv_key == NULL)
 862         return 0;
 863     if (buf == NULL)
 864         return buf_len;
 865     else if (len < buf_len)
 866         return 0;
 867
 868     /* Octetstring may need leading zeros if BN is to short */
 869
 870     if (BN_bn2binpad(eckey->priv_key, buf, buf_len) == -1) {
 871         ECerr(EC_F_EC_KEY_SIMPLE_PRIV2OCT, EC_R_BUFFER_TOO_SMALL);
 872         return 0;
 873     }
 874
 875     return buf_len;
 876 }
 877
 878 int EC_KEY_oct2priv(EC_KEY *eckey, const unsigned char *buf, size_t len)
 879 {
 880     int ret;
 881
 882     if (eckey->group == NULL || eckey->group->meth == NULL)
 883         return 0;
 884     if (eckey->group->meth->oct2priv == NULL) {
 885         ECerr(EC_F_EC_KEY_OCT2PRIV, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
 886         return 0;
 887     }
 888     ret = eckey->group->meth->oct2priv(eckey, buf, len);
 889     if (ret == 1)
 890         eckey->dirty_cnt++;
 891     return ret;
 892 }
 893
 894 int ec_key_simple_oct2priv(EC_KEY *eckey, const unsigned char *buf, size_t len)
 895 {
 896     if (eckey->priv_key == NULL)
 897         eckey->priv_key = BN_secure_new();
 898     if (eckey->priv_key == NULL) {
 899         ECerr(EC_F_EC_KEY_SIMPLE_OCT2PRIV, ERR_R_MALLOC_FAILURE);
 900         return 0;
 901     }
 902     eckey->priv_key = BN_bin2bn(buf, len, eckey->priv_key);
 903     if (eckey->priv_key == NULL) {
 904         ECerr(EC_F_EC_KEY_SIMPLE_OCT2PRIV, ERR_R_BN_LIB);
 905         return 0;
 906     }
 907     eckey->dirty_cnt++;
 908     return 1;
 909 }
 910
 911 size_t EC_KEY_priv2buf(const EC_KEY *eckey, unsigned char **pbuf)
 912 {
 913     size_t len;
 914     unsigned char *buf;
 915
 916     len = EC_KEY_priv2oct(eckey, NULL, 0);
 917     if (len == 0)
 918         return 0;
 919     if ((buf = OPENSSL_malloc(len)) == NULL) {
 920         ECerr(EC_F_EC_KEY_PRIV2BUF, ERR_R_MALLOC_FAILURE);
 921         return 0;
 922     }
 923     len = EC_KEY_priv2oct(eckey, buf, len);
 924     if (len == 0) {
 925         OPENSSL_free(buf);
 926         return 0;
 927     }
 928     *pbuf = buf;
 929     return len;
 930 }
 931
 932 int EC_KEY_can_sign(const EC_KEY *eckey)
 933 {
 934     if (eckey->group == NULL || eckey->group->meth == NULL
 935         || (eckey->group->meth->flags & EC_FLAGS_NO_SIGN))
 936         return 0;
 937     return 1;
 938 }
 939
 940 /*
 941  * FIPS 140-2 IG 9.9 AS09.33
 942  * Perform a sign/verify operation.
 943  *
 944  * NOTE: When generating keys for key-agreement schemes - FIPS 140-2 IG 9.9
 945  * states that no additional pairwise tests are required (apart from the tests
 946  * specified in SP800-56A) when generating keys. Hence pairwise ECDH tests are
 947  * omitted here.
 948  */
 949 static int ecdsa_keygen_pairwise_test(EC_KEY *eckey, OSSL_CALLBACK *cb,
 950                                       void *cbarg)
 951 {
 952     int ret = 0;
 953     unsigned char dgst[16] = {0};
 954     int dgst_len = (int)sizeof(dgst);
 955     ECDSA_SIG *sig = NULL;
 956     OSSL_SELF_TEST *st = NULL;
 957
 958     st = OSSL_SELF_TEST_new(cb, cbarg);
 959     if (st == NULL)
 960         return 0;
 961
 962     OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT,
 963                            OSSL_SELF_TEST_DESC_PCT_ECDSA);
 964
 965     sig = ECDSA_do_sign(dgst, dgst_len, eckey);
 966     if (sig == NULL)
 967         goto err;
 968
 969     OSSL_SELF_TEST_oncorrupt_byte(st, dgst);
 970
 971     if (ECDSA_do_verify(dgst, dgst_len, sig, eckey) != 1)
 972         goto err;
 973
 974     ret = 1;
 975 err:
 976     OSSL_SELF_TEST_onend(st, ret);
 977     OSSL_SELF_TEST_free(st);
 978     ECDSA_SIG_free(sig);
 979     return ret;
 980 }