crypto/ec/ecdsa_ossl.c

   1 /*
   2  * Copyright 2002-2020 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  * ECDSA low level APIs are deprecated for public use, but still ok for
  12  * internal use.
  13  */
  14 #include "internal/deprecated.h"
  15
  16 #include <string.h>
  17 #include <openssl/err.h>
  18 #include <openssl/obj_mac.h>
  19 #include <openssl/rand.h>
  20 #include "crypto/bn.h"
  21 #include "ec_local.h"
  22
  23 int ossl_ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
  24                           BIGNUM **rp)
  25 {
  26     if (eckey->group->meth->ecdsa_sign_setup == NULL) {
  27         ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_ECDSA);
  28         return 0;
  29     }
  30
  31     return eckey->group->meth->ecdsa_sign_setup(eckey, ctx_in, kinvp, rp);
  32 }
  33
  34 ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
  35                                const BIGNUM *in_kinv, const BIGNUM *in_r,
  36                                EC_KEY *eckey)
  37 {
  38     if (eckey->group->meth->ecdsa_sign_sig == NULL) {
  39         ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_ECDSA);
  40         return NULL;
  41     }
  42
  43     return eckey->group->meth->ecdsa_sign_sig(dgst, dgst_len,
  44                                               in_kinv, in_r, eckey);
  45 }
  46
  47 int ossl_ecdsa_verify_sig(const unsigned char *dgst, int dgst_len,
  48                           const ECDSA_SIG *sig, EC_KEY *eckey)
  49 {
  50     if (eckey->group->meth->ecdsa_verify_sig == NULL) {
  51         ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_ECDSA);
  52         return 0;
  53     }
  54
  55     return eckey->group->meth->ecdsa_verify_sig(dgst, dgst_len, sig, eckey);
  56 }
  57
  58 int ossl_ecdsa_sign(int type, const unsigned char *dgst, int dlen,
  59                     unsigned char *sig, unsigned int *siglen,
  60                     const BIGNUM *kinv, const BIGNUM *r, EC_KEY *eckey)
  61 {
  62     ECDSA_SIG *s;
  63
  64     s = ECDSA_do_sign_ex(dgst, dlen, kinv, r, eckey);
  65     if (s == NULL) {
  66         *siglen = 0;
  67         return 0;
  68     }
  69     *siglen = i2d_ECDSA_SIG(s, &sig);
  70     ECDSA_SIG_free(s);
  71     return 1;
  72 }
  73
  74 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
  75                             BIGNUM **kinvp, BIGNUM **rp,
  76                             const unsigned char *dgst, int dlen)
  77 {
  78     BN_CTX *ctx = NULL;
  79     BIGNUM *k = NULL, *r = NULL, *X = NULL;
  80     const BIGNUM *order;
  81     EC_POINT *tmp_point = NULL;
  82     const EC_GROUP *group;
  83     int ret = 0;
  84     int order_bits;
  85     const BIGNUM *priv_key;
  86
  87     if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
  88         ERR_raise(ERR_LIB_EC, ERR_R_PASSED_NULL_PARAMETER);
  89         return 0;
  90     }
  91     if ((priv_key = EC_KEY_get0_private_key(eckey)) == NULL) {
  92         ERR_raise(ERR_LIB_EC, EC_R_MISSING_PRIVATE_KEY);
  93         return 0;
  94     }
  95
  96     if (!EC_KEY_can_sign(eckey)) {
  97         ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
  98         return 0;
  99     }
 100
 101     if ((ctx = ctx_in) == NULL) {
 102         if ((ctx = BN_CTX_new_ex(eckey->libctx)) == NULL) {
 103             ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 104             return 0;
 105         }
 106     }
 107
 108     k = BN_secure_new();        /* this value is later returned in *kinvp */
 109     r = BN_new();               /* this value is later returned in *rp */
 110     X = BN_new();
 111     if (k == NULL || r == NULL || X == NULL) {
 112         ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 113         goto err;
 114     }
 115     if ((tmp_point = EC_POINT_new(group)) == NULL) {
 116         ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
 117         goto err;
 118     }
 119     order = EC_GROUP_get0_order(group);
 120
 121     /* Preallocate space */
 122     order_bits = BN_num_bits(order);
 123     if (!BN_set_bit(k, order_bits)
 124         || !BN_set_bit(r, order_bits)
 125         || !BN_set_bit(X, order_bits))
 126         goto err;
 127
 128     do {
 129         /* get random k */
 130         do {
 131             if (dgst != NULL) {
 132                 if (!BN_generate_dsa_nonce(k, order, priv_key,
 133                                            dgst, dlen, ctx)) {
 134                     ERR_raise(ERR_LIB_EC, EC_R_RANDOM_NUMBER_GENERATION_FAILED);
 135                     goto err;
 136                 }
 137             } else {
 138                 if (!BN_priv_rand_range_ex(k, order, ctx)) {
 139                     ERR_raise(ERR_LIB_EC, EC_R_RANDOM_NUMBER_GENERATION_FAILED);
 140                     goto err;
 141                 }
 142             }
 143         } while (BN_is_zero(k));
 144
 145         /* compute r the x-coordinate of generator * k */
 146         if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
 147             ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
 148             goto err;
 149         }
 150
 151         if (!EC_POINT_get_affine_coordinates(group, tmp_point, X, NULL, ctx)) {
 152             ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
 153             goto err;
 154         }
 155
 156         if (!BN_nnmod(r, X, order, ctx)) {
 157             ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 158             goto err;
 159         }
 160     } while (BN_is_zero(r));
 161
 162     /* compute the inverse of k */
 163     if (!ec_group_do_inverse_ord(group, k, k, ctx)) {
 164         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 165         goto err;
 166     }
 167
 168     /* clear old values if necessary */
 169     BN_clear_free(*rp);
 170     BN_clear_free(*kinvp);
 171     /* save the pre-computed values  */
 172     *rp = r;
 173     *kinvp = k;
 174     ret = 1;
 175  err:
 176     if (!ret) {
 177         BN_clear_free(k);
 178         BN_clear_free(r);
 179     }
 180     if (ctx != ctx_in)
 181         BN_CTX_free(ctx);
 182     EC_POINT_free(tmp_point);
 183     BN_clear_free(X);
 184     return ret;
 185 }
 186
 187 int ecdsa_simple_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
 188                             BIGNUM **rp)
 189 {
 190     return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
 191 }
 192
 193 ECDSA_SIG *ecdsa_simple_sign_sig(const unsigned char *dgst, int dgst_len,
 194                                  const BIGNUM *in_kinv, const BIGNUM *in_r,
 195                                  EC_KEY *eckey)
 196 {
 197     int ok = 0, i;
 198     BIGNUM *kinv = NULL, *s, *m = NULL;
 199     const BIGNUM *order, *ckinv;
 200     BN_CTX *ctx = NULL;
 201     const EC_GROUP *group;
 202     ECDSA_SIG *ret;
 203     const BIGNUM *priv_key;
 204
 205     group = EC_KEY_get0_group(eckey);
 206     priv_key = EC_KEY_get0_private_key(eckey);
 207
 208     if (group == NULL) {
 209         ERR_raise(ERR_LIB_EC, ERR_R_PASSED_NULL_PARAMETER);
 210         return NULL;
 211     }
 212     if (priv_key == NULL) {
 213         ERR_raise(ERR_LIB_EC, EC_R_MISSING_PRIVATE_KEY);
 214         return NULL;
 215     }
 216
 217     if (!EC_KEY_can_sign(eckey)) {
 218         ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
 219         return NULL;
 220     }
 221
 222     ret = ECDSA_SIG_new();
 223     if (ret == NULL) {
 224         ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 225         return NULL;
 226     }
 227     ret->r = BN_new();
 228     ret->s = BN_new();
 229     if (ret->r == NULL || ret->s == NULL) {
 230         ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 231         goto err;
 232     }
 233     s = ret->s;
 234
 235     if ((ctx = BN_CTX_new_ex(eckey->libctx)) == NULL
 236         || (m = BN_new()) == NULL) {
 237         ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 238         goto err;
 239     }
 240
 241     order = EC_GROUP_get0_order(group);
 242     i = BN_num_bits(order);
 243     /*
 244      * Need to truncate digest if it is too long: first truncate whole bytes.
 245      */
 246     if (8 * dgst_len > i)
 247         dgst_len = (i + 7) / 8;
 248     if (!BN_bin2bn(dgst, dgst_len, m)) {
 249         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 250         goto err;
 251     }
 252     /* If still too long, truncate remaining bits with a shift */
 253     if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
 254         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 255         goto err;
 256     }
 257     do {
 258         if (in_kinv == NULL || in_r == NULL) {
 259             if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len)) {
 260                 ERR_raise(ERR_LIB_EC, ERR_R_ECDSA_LIB);
 261                 goto err;
 262             }
 263             ckinv = kinv;
 264         } else {
 265             ckinv = in_kinv;
 266             if (BN_copy(ret->r, in_r) == NULL) {
 267                 ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 268                 goto err;
 269             }
 270         }
 271
 272         /*
 273          * With only one multiplicant being in Montgomery domain
 274          * multiplication yields real result without post-conversion.
 275          * Also note that all operations but last are performed with
 276          * zero-padded vectors. Last operation, BN_mod_mul_montgomery
 277          * below, returns user-visible value with removed zero padding.
 278          */
 279         if (!bn_to_mont_fixed_top(s, ret->r, group->mont_data, ctx)
 280             || !bn_mul_mont_fixed_top(s, s, priv_key, group->mont_data, ctx)) {
 281             ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 282             goto err;
 283         }
 284         if (!bn_mod_add_fixed_top(s, s, m, order)) {
 285             ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 286             goto err;
 287         }
 288         /*
 289          * |s| can still be larger than modulus, because |m| can be. In
 290          * such case we count on Montgomery reduction to tie it up.
 291          */
 292         if (!bn_to_mont_fixed_top(s, s, group->mont_data, ctx)
 293             || !BN_mod_mul_montgomery(s, s, ckinv, group->mont_data, ctx)) {
 294             ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 295             goto err;
 296         }
 297
 298         if (BN_is_zero(s)) {
 299             /*
 300              * if kinv and r have been supplied by the caller, don't
 301              * generate new kinv and r values
 302              */
 303             if (in_kinv != NULL && in_r != NULL) {
 304                 ERR_raise(ERR_LIB_EC, EC_R_NEED_NEW_SETUP_VALUES);
 305                 goto err;
 306             }
 307         } else {
 308             /* s != 0 => we have a valid signature */
 309             break;
 310         }
 311     } while (1);
 312
 313     ok = 1;
 314  err:
 315     if (!ok) {
 316         ECDSA_SIG_free(ret);
 317         ret = NULL;
 318     }
 319     BN_CTX_free(ctx);
 320     BN_clear_free(m);
 321     BN_clear_free(kinv);
 322     return ret;
 323 }
 324
 325 /*-
 326  * returns
 327  *      1: correct signature
 328  *      0: incorrect signature
 329  *     -1: error
 330  */
 331 int ossl_ecdsa_verify(int type, const unsigned char *dgst, int dgst_len,
 332                       const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)
 333 {
 334     ECDSA_SIG *s;
 335     const unsigned char *p = sigbuf;
 336     unsigned char *der = NULL;
 337     int derlen = -1;
 338     int ret = -1;
 339
 340     s = ECDSA_SIG_new();
 341     if (s == NULL)
 342         return ret;
 343     if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
 344         goto err;
 345     /* Ensure signature uses DER and doesn't have trailing garbage */
 346     derlen = i2d_ECDSA_SIG(s, &der);
 347     if (derlen != sig_len || memcmp(sigbuf, der, derlen) != 0)
 348         goto err;
 349     ret = ECDSA_do_verify(dgst, dgst_len, s, eckey);
 350  err:
 351     OPENSSL_free(der);
 352     ECDSA_SIG_free(s);
 353     return ret;
 354 }
 355
 356 int ecdsa_simple_verify_sig(const unsigned char *dgst, int dgst_len,
 357                             const ECDSA_SIG *sig, EC_KEY *eckey)
 358 {
 359     int ret = -1, i;
 360     BN_CTX *ctx;
 361     const BIGNUM *order;
 362     BIGNUM *u1, *u2, *m, *X;
 363     EC_POINT *point = NULL;
 364     const EC_GROUP *group;
 365     const EC_POINT *pub_key;
 366
 367     /* check input values */
 368     if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
 369         (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
 370         ERR_raise(ERR_LIB_EC, EC_R_MISSING_PARAMETERS);
 371         return -1;
 372     }
 373
 374     if (!EC_KEY_can_sign(eckey)) {
 375         ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
 376         return -1;
 377     }
 378
 379     ctx = BN_CTX_new_ex(eckey->libctx);
 380     if (ctx == NULL) {
 381         ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 382         return -1;
 383     }
 384     BN_CTX_start(ctx);
 385     u1 = BN_CTX_get(ctx);
 386     u2 = BN_CTX_get(ctx);
 387     m = BN_CTX_get(ctx);
 388     X = BN_CTX_get(ctx);
 389     if (X == NULL) {
 390         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 391         goto err;
 392     }
 393
 394     order = EC_GROUP_get0_order(group);
 395     if (order == NULL) {
 396         ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
 397         goto err;
 398     }
 399
 400     if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
 401         BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
 402         BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
 403         ERR_raise(ERR_LIB_EC, EC_R_BAD_SIGNATURE);
 404         ret = 0;                /* signature is invalid */
 405         goto err;
 406     }
 407     /* calculate tmp1 = inv(S) mod order */
 408     if (!ec_group_do_inverse_ord(group, u2, sig->s, ctx)) {
 409         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 410         goto err;
 411     }
 412     /* digest -> m */
 413     i = BN_num_bits(order);
 414     /*
 415      * Need to truncate digest if it is too long: first truncate whole bytes.
 416      */
 417     if (8 * dgst_len > i)
 418         dgst_len = (i + 7) / 8;
 419     if (!BN_bin2bn(dgst, dgst_len, m)) {
 420         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 421         goto err;
 422     }
 423     /* If still too long truncate remaining bits with a shift */
 424     if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
 425         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 426         goto err;
 427     }
 428     /* u1 = m * tmp mod order */
 429     if (!BN_mod_mul(u1, m, u2, order, ctx)) {
 430         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 431         goto err;
 432     }
 433     /* u2 = r * w mod q */
 434     if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
 435         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 436         goto err;
 437     }
 438
 439     if ((point = EC_POINT_new(group)) == NULL) {
 440         ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
 441         goto err;
 442     }
 443     if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
 444         ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
 445         goto err;
 446     }
 447
 448     if (!EC_POINT_get_affine_coordinates(group, point, X, NULL, ctx)) {
 449         ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
 450         goto err;
 451     }
 452
 453     if (!BN_nnmod(u1, X, order, ctx)) {
 454         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
 455         goto err;
 456     }
 457     /*  if the signature is correct u1 is equal to sig->r */
 458     ret = (BN_ucmp(u1, sig->r) == 0);
 459  err:
 460     BN_CTX_end(ctx);
 461     BN_CTX_free(ctx);
 462     EC_POINT_free(point);
 463     return ret;
 464 }