crypto/openssl-0.9/crypto/ecdsa/ecs_ossl.c

   1 /* crypto/ecdsa/ecs_ossl.c */
   2 /*
   3  * Written by Nils Larsch for the OpenSSL project
   4  */
   5 /* ====================================================================
   6  * Copyright (c) 1998-2004 The OpenSSL Project.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  *
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in
  17  *    the documentation and/or other materials provided with the
  18  *    distribution.
  19  *
  20  * 3. All advertising materials mentioning features or use of this
  21  *    software must display the following acknowledgment:
  22  *    "This product includes software developed by the OpenSSL Project
  23  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  24  *
  25  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  26  *    endorse or promote products derived from this software without
  27  *    prior written permission. For written permission, please contact
  28  *    openssl-core@OpenSSL.org.
  29  *
  30  * 5. Products derived from this software may not be called "OpenSSL"
  31  *    nor may "OpenSSL" appear in their names without prior written
  32  *    permission of the OpenSSL Project.
  33  *
  34  * 6. Redistributions of any form whatsoever must retain the following
  35  *    acknowledgment:
  36  *    "This product includes software developed by the OpenSSL Project
  37  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  38  *
  39  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  40  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  42  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  43  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  45  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  48  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  49  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  50  * OF THE POSSIBILITY OF SUCH DAMAGE.
  51  * ====================================================================
  52  *
  53  * This product includes cryptographic software written by Eric Young
  54  * (eay@cryptsoft.com).  This product includes software written by Tim
  55  * Hudson (tjh@cryptsoft.com).
  56  *
  57  */
  58
  59 #include "ecs_locl.h"
  60 #include <openssl/err.h>
  61 #include <openssl/obj_mac.h>
  62 #include <openssl/bn.h>
  63
  64 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen,
  65                 const BIGNUM *, const BIGNUM *, EC_KEY *eckey);
  66 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
  67                 BIGNUM **rp);
  68 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
  69                 const ECDSA_SIG *sig, EC_KEY *eckey);
  70
  71 static ECDSA_METHOD openssl_ecdsa_meth = {
  72         "OpenSSL ECDSA method",
  73         ecdsa_do_sign,
  74         ecdsa_sign_setup,
  75         ecdsa_do_verify,
  76 #if 0
  77         NULL, /* init     */
  78         NULL, /* finish   */
  79 #endif
  80         0,    /* flags    */
  81         NULL  /* app_data */
  82 };
  83
  84 const ECDSA_METHOD *ECDSA_OpenSSL(void)
  85 {
  86         return &openssl_ecdsa_meth;
  87 }
  88
  89 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
  90                 BIGNUM **rp)
  91 {
  92         BN_CTX   *ctx = NULL;
  93         BIGNUM   *k = NULL, *r = NULL, *order = NULL, *X = NULL;
  94         EC_POINT *tmp_point=NULL;
  95         const EC_GROUP *group;
  96         int      ret = 0;
  97
  98         if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL)
  99         {
 100                 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
 101                 return 0;
 102         }
 103
 104         if (ctx_in == NULL)
 105         {
 106                 if ((ctx = BN_CTX_new()) == NULL)
 107                 {
 108                         ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_MALLOC_FAILURE);
 109                         return 0;
 110                 }
 111         }
 112         else
 113                 ctx = ctx_in;
 114
 115         k     = BN_new();       /* this value is later returned in *kinvp */
 116         r     = BN_new();       /* this value is later returned in *rp    */
 117         order = BN_new();
 118         X     = BN_new();
 119         if (!k || !r || !order || !X)
 120         {
 121                 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
 122                 goto err;
 123         }
 124         if ((tmp_point = EC_POINT_new(group)) == NULL)
 125         {
 126                 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
 127                 goto err;
 128         }
 129         if (!EC_GROUP_get_order(group, order, ctx))
 130         {
 131                 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
 132                 goto err;
 133         }
 134
 135         do
 136         {
 137                 /* get random k */
 138                 do
 139                         if (!BN_rand_range(k, order))
 140                         {
 141                                 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
 142                                  ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
 143                                 goto err;
 144                         }
 145                 while (BN_is_zero(k));
 146
 147                 /* compute r the x-coordinate of generator * k */
 148                 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx))
 149                 {
 150                         ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
 151                         goto err;
 152                 }
 153                 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
 154                 {
 155                         if (!EC_POINT_get_affine_coordinates_GFp(group,
 156                                 tmp_point, X, NULL, ctx))
 157                         {
 158                                 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB);
 159                                 goto err;
 160                         }
 161                 }
 162                 else /* NID_X9_62_characteristic_two_field */
 163                 {
 164                         if (!EC_POINT_get_affine_coordinates_GF2m(group,
 165                                 tmp_point, X, NULL, ctx))
 166                         {
 167                                 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB);
 168                                 goto err;
 169                         }
 170                 }
 171                 if (!BN_nnmod(r, X, order, ctx))
 172                 {
 173                         ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
 174                         goto err;
 175                 }
 176         }
 177         while (BN_is_zero(r));
 178
 179         /* compute the inverse of k */
 180         if (!BN_mod_inverse(k, k, order, ctx))
 181         {
 182                 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
 183                 goto err;
 184         }
 185         /* clear old values if necessary */
 186         if (*rp != NULL)
 187                 BN_clear_free(*rp);
 188         if (*kinvp != NULL)
 189                 BN_clear_free(*kinvp);
 190         /* save the pre-computed values  */
 191         *rp    = r;
 192         *kinvp = k;
 193         ret = 1;
 194 err:
 195         if (!ret)
 196         {
 197                 if (k != NULL) BN_clear_free(k);
 198                 if (r != NULL) BN_clear_free(r);
 199         }
 200         if (ctx_in == NULL)
 201                 BN_CTX_free(ctx);
 202         if (order != NULL)
 203                 BN_free(order);
 204         if (tmp_point != NULL)
 205                 EC_POINT_free(tmp_point);
 206         if (X)
 207                 BN_clear_free(X);
 208         return(ret);
 209 }
 210
 211
 212 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
 213                 const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *eckey)
 214 {
 215         int     ok = 0;
 216         BIGNUM *kinv=NULL, *s, *m=NULL,*tmp=NULL,*order=NULL;
 217         const BIGNUM *ckinv;
 218         BN_CTX     *ctx = NULL;
 219         const EC_GROUP   *group;
 220         ECDSA_SIG  *ret;
 221         ECDSA_DATA *ecdsa;
 222         const BIGNUM *priv_key;
 223
 224         ecdsa    = ecdsa_check(eckey);
 225         group    = EC_KEY_get0_group(eckey);
 226         priv_key = EC_KEY_get0_private_key(eckey);
 227
 228         if (group == NULL || priv_key == NULL || ecdsa == NULL)
 229         {
 230                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER);
 231                 return NULL;
 232         }
 233
 234         ret = ECDSA_SIG_new();
 235         if (!ret)
 236         {
 237                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
 238                 return NULL;
 239         }
 240         s = ret->s;
 241
 242         if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL ||
 243                 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL)
 244         {
 245                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
 246                 goto err;
 247         }
 248
 249         if (!EC_GROUP_get_order(group, order, ctx))
 250         {
 251                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB);
 252                 goto err;
 253         }
 254         if (8 * dgst_len > BN_num_bits(order))
 255         {
 256                 /* XXX
 257                  *
 258                  * Should provide for optional hash truncation:
 259                  * Keep the BN_num_bits(order) leftmost bits of dgst
 260                  * (see March 2006 FIPS 186-3 draft, which has a few
 261                  * confusing errors in this part though)
 262                  */
 263
 264                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,
 265                         ECDSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
 266                 goto err;
 267         }
 268
 269         if (!BN_bin2bn(dgst, dgst_len, m))
 270         {
 271                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
 272                 goto err;
 273         }
 274         do
 275         {
 276                 if (in_kinv == NULL || in_r == NULL)
 277                 {
 278                         if (!ECDSA_sign_setup(eckey, ctx, &kinv, &ret->r))
 279                         {
 280                                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,ERR_R_ECDSA_LIB);
 281                                 goto err;
 282                         }
 283                         ckinv = kinv;
 284                 }
 285                 else
 286                 {
 287                         ckinv  = in_kinv;
 288                         if (BN_copy(ret->r, in_r) == NULL)
 289                         {
 290                                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
 291                                 goto err;
 292                         }
 293                 }
 294
 295                 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx))
 296                 {
 297                         ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
 298                         goto err;
 299                 }
 300                 if (!BN_mod_add_quick(s, tmp, m, order))
 301                 {
 302                         ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
 303                         goto err;
 304                 }
 305                 if (!BN_mod_mul(s, s, ckinv, order, ctx))
 306                 {
 307                         ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
 308                         goto err;
 309                 }
 310                 if (BN_is_zero(s))
 311                 {
 312                         /* if kinv and r have been supplied by the caller
 313                          * don't to generate new kinv and r values */
 314                         if (in_kinv != NULL && in_r != NULL)
 315                         {
 316                                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ECDSA_R_NEED_NEW_SETUP_VALUES);
 317                                 goto err;
 318                         }
 319                 }
 320                 else
 321                         /* s != 0 => we have a valid signature */
 322                         break;
 323         }
 324         while (1);
 325
 326         ok = 1;
 327 err:
 328         if (!ok)
 329         {
 330                 ECDSA_SIG_free(ret);
 331                 ret = NULL;
 332         }
 333         if (ctx)
 334                 BN_CTX_free(ctx);
 335         if (m)
 336                 BN_clear_free(m);
 337         if (tmp)
 338                 BN_clear_free(tmp);
 339         if (order)
 340                 BN_free(order);
 341         if (kinv)
 342                 BN_clear_free(kinv);
 343         return ret;
 344 }
 345
 346 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
 347                 const ECDSA_SIG *sig, EC_KEY *eckey)
 348 {
 349         int ret = -1;
 350         BN_CTX   *ctx;
 351         BIGNUM   *order, *u1, *u2, *m, *X;
 352         EC_POINT *point = NULL;
 353         const EC_GROUP *group;
 354         const EC_POINT *pub_key;
 355
 356         /* check input values */
 357         if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
 358             (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL)
 359         {
 360                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS);
 361                 return -1;
 362         }
 363
 364         ctx = BN_CTX_new();
 365         if (!ctx)
 366         {
 367                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
 368                 return -1;
 369         }
 370         BN_CTX_start(ctx);
 371         order = BN_CTX_get(ctx);
 372         u1    = BN_CTX_get(ctx);
 373         u2    = BN_CTX_get(ctx);
 374         m     = BN_CTX_get(ctx);
 375         X     = BN_CTX_get(ctx);
 376         if (!X)
 377         {
 378                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
 379                 goto err;
 380         }
 381
 382         if (!EC_GROUP_get_order(group, order, ctx))
 383         {
 384                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
 385                 goto err;
 386         }
 387         if (8 * dgst_len > BN_num_bits(order))
 388         {
 389                 /* XXX
 390                  *
 391                  * Should provide for optional hash truncation:
 392                  * Keep the BN_num_bits(order) leftmost bits of dgst
 393                  * (see March 2006 FIPS 186-3 draft, which has a few
 394                  * confusing errors in this part though)
 395                  */
 396
 397                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY,
 398                         ECDSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
 399                 ret = 0;
 400                 goto err;
 401         }
 402
 403         if (BN_is_zero(sig->r)          || BN_is_negative(sig->r) ||
 404             BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s)  ||
 405             BN_is_negative(sig->s)      || BN_ucmp(sig->s, order) >= 0)
 406         {
 407                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE);
 408                 ret = 0;        /* signature is invalid */
 409                 goto err;
 410         }
 411         /* calculate tmp1 = inv(S) mod order */
 412         if (!BN_mod_inverse(u2, sig->s, order, ctx))
 413         {
 414                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
 415                 goto err;
 416         }
 417         /* digest -> m */
 418         if (!BN_bin2bn(dgst, dgst_len, m))
 419         {
 420                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
 421                 goto err;
 422         }
 423         /* u1 = m * tmp mod order */
 424         if (!BN_mod_mul(u1, m, u2, order, ctx))
 425         {
 426                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
 427                 goto err;
 428         }
 429         /* u2 = r * w mod q */
 430         if (!BN_mod_mul(u2, sig->r, u2, order, ctx))
 431         {
 432                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
 433                 goto err;
 434         }
 435
 436         if ((point = EC_POINT_new(group)) == NULL)
 437         {
 438                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
 439                 goto err;
 440         }
 441         if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx))
 442         {
 443                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
 444                 goto err;
 445         }
 446         if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
 447         {
 448                 if (!EC_POINT_get_affine_coordinates_GFp(group,
 449                         point, X, NULL, ctx))
 450                 {
 451                         ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
 452                         goto err;
 453                 }
 454         }
 455         else /* NID_X9_62_characteristic_two_field */
 456         {
 457                 if (!EC_POINT_get_affine_coordinates_GF2m(group,
 458                         point, X, NULL, ctx))
 459                 {
 460                         ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
 461                         goto err;
 462                 }
 463         }
 464
 465         if (!BN_nnmod(u1, X, order, ctx))
 466         {
 467                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
 468                 goto err;
 469         }
 470         /*  if the signature is correct u1 is equal to sig->r */
 471         ret = (BN_ucmp(u1, sig->r) == 0);
 472 err:
 473         BN_CTX_end(ctx);
 474         BN_CTX_free(ctx);
 475         if (point)
 476                 EC_POINT_free(point);
 477         return ret;
 478 }