crypto/ec/ecdsa_ossl.c

   1 /*
   2  * Copyright 2002-2018 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         ECerr(EC_F_OSSL_ECDSA_SIGN_SETUP, 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         ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, 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         ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, 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         ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
  89         return 0;
  90     }
  91     if ((priv_key = EC_KEY_get0_private_key(eckey)) == NULL) {
  92         ECerr(EC_F_ECDSA_SIGN_SETUP, EC_R_MISSING_PRIVATE_KEY);
  93         return 0;
  94     }
  95
  96     if (!EC_KEY_can_sign(eckey)) {
  97         ECerr(EC_F_ECDSA_SIGN_SETUP, 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             ECerr(EC_F_ECDSA_SIGN_SETUP, 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         ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
 113         goto err;
 114     }
 115     if ((tmp_point = EC_POINT_new(group)) == NULL) {
 116         ECerr(EC_F_ECDSA_SIGN_SETUP, 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                     ECerr(EC_F_ECDSA_SIGN_SETUP,
 135                           EC_R_RANDOM_NUMBER_GENERATION_FAILED);
 136                     goto err;
 137                 }
 138             } else {
 139                 if (!BN_priv_rand_range_ex(k, order, ctx)) {
 140                     ECerr(EC_F_ECDSA_SIGN_SETUP,
 141                           EC_R_RANDOM_NUMBER_GENERATION_FAILED);
 142                     goto err;
 143                 }
 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             ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
 150             goto err;
 151         }
 152
 153         if (!EC_POINT_get_affine_coordinates(group, tmp_point, X, NULL, ctx)) {
 154             ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
 155             goto err;
 156         }
 157
 158         if (!BN_nnmod(r, X, order, ctx)) {
 159             ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
 160             goto err;
 161         }
 162     } while (BN_is_zero(r));
 163
 164     /* compute the inverse of k */
 165     if (!ec_group_do_inverse_ord(group, k, k, ctx)) {
 166         ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
 167         goto err;
 168     }
 169
 170     /* clear old values if necessary */
 171     BN_clear_free(*rp);
 172     BN_clear_free(*kinvp);
 173     /* save the pre-computed values  */
 174     *rp = r;
 175     *kinvp = k;
 176     ret = 1;
 177  err:
 178     if (!ret) {
 179         BN_clear_free(k);
 180         BN_clear_free(r);
 181     }
 182     if (ctx != ctx_in)
 183         BN_CTX_free(ctx);
 184     EC_POINT_free(tmp_point);
 185     BN_clear_free(X);
 186     return ret;
 187 }
 188
 189 int ecdsa_simple_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
 190                             BIGNUM **rp)
 191 {
 192     return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
 193 }
 194
 195 ECDSA_SIG *ecdsa_simple_sign_sig(const unsigned char *dgst, int dgst_len,
 196                                  const BIGNUM *in_kinv, const BIGNUM *in_r,
 197                                  EC_KEY *eckey)
 198 {
 199     int ok = 0, i;
 200     BIGNUM *kinv = NULL, *s, *m = NULL;
 201     const BIGNUM *order, *ckinv;
 202     BN_CTX *ctx = NULL;
 203     const EC_GROUP *group;
 204     ECDSA_SIG *ret;
 205     const BIGNUM *priv_key;
 206
 207     group = EC_KEY_get0_group(eckey);
 208     priv_key = EC_KEY_get0_private_key(eckey);
 209
 210     if (group == NULL) {
 211         ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_PASSED_NULL_PARAMETER);
 212         return NULL;
 213     }
 214     if (priv_key == NULL) {
 215         ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, EC_R_MISSING_PRIVATE_KEY);
 216         return NULL;
 217     }
 218
 219     if (!EC_KEY_can_sign(eckey)) {
 220         ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
 221         return NULL;
 222     }
 223
 224     ret = ECDSA_SIG_new();
 225     if (ret == NULL) {
 226         ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_MALLOC_FAILURE);
 227         return NULL;
 228     }
 229     ret->r = BN_new();
 230     ret->s = BN_new();
 231     if (ret->r == NULL || ret->s == NULL) {
 232         ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_MALLOC_FAILURE);
 233         goto err;
 234     }
 235     s = ret->s;
 236
 237     if ((ctx = BN_CTX_new_ex(eckey->libctx)) == NULL
 238         || (m = BN_new()) == NULL) {
 239         ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_MALLOC_FAILURE);
 240         goto err;
 241     }
 242
 243     order = EC_GROUP_get0_order(group);
 244     i = BN_num_bits(order);
 245     /*
 246      * Need to truncate digest if it is too long: first truncate whole bytes.
 247      */
 248     if (8 * dgst_len > i)
 249         dgst_len = (i + 7) / 8;
 250     if (!BN_bin2bn(dgst, dgst_len, m)) {
 251         ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_BN_LIB);
 252         goto err;
 253     }
 254     /* If still too long, truncate remaining bits with a shift */
 255     if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
 256         ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_BN_LIB);
 257         goto err;
 258     }
 259     do {
 260         if (in_kinv == NULL || in_r == NULL) {
 261             if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len)) {
 262                 ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_ECDSA_LIB);
 263                 goto err;
 264             }
 265             ckinv = kinv;
 266         } else {
 267             ckinv = in_kinv;
 268             if (BN_copy(ret->r, in_r) == NULL) {
 269                 ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_MALLOC_FAILURE);
 270                 goto err;
 271             }
 272         }
 273
 274         /*
 275          * With only one multiplicant being in Montgomery domain
 276          * multiplication yields real result without post-conversion.
 277          * Also note that all operations but last are performed with
 278          * zero-padded vectors. Last operation, BN_mod_mul_montgomery
 279          * below, returns user-visible value with removed zero padding.
 280          */
 281         if (!bn_to_mont_fixed_top(s, ret->r, group->mont_data, ctx)
 282             || !bn_mul_mont_fixed_top(s, s, priv_key, group->mont_data, ctx)) {
 283             ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_BN_LIB);
 284             goto err;
 285         }
 286         if (!bn_mod_add_fixed_top(s, s, m, order)) {
 287             ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_BN_LIB);
 288             goto err;
 289         }
 290         /*
 291          * |s| can still be larger than modulus, because |m| can be. In
 292          * such case we count on Montgomery reduction to tie it up.
 293          */
 294         if (!bn_to_mont_fixed_top(s, s, group->mont_data, ctx)
 295             || !BN_mod_mul_montgomery(s, s, ckinv, group->mont_data, ctx)) {
 296             ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, ERR_R_BN_LIB);
 297             goto err;
 298         }
 299
 300         if (BN_is_zero(s)) {
 301             /*
 302              * if kinv and r have been supplied by the caller, don't
 303              * generate new kinv and r values
 304              */
 305             if (in_kinv != NULL && in_r != NULL) {
 306                 ECerr(EC_F_ECDSA_SIMPLE_SIGN_SIG, EC_R_NEED_NEW_SETUP_VALUES);
 307                 goto err;
 308             }
 309         } else {
 310             /* s != 0 => we have a valid signature */
 311             break;
 312         }
 313     } while (1);
 314
 315     ok = 1;
 316  err:
 317     if (!ok) {
 318         ECDSA_SIG_free(ret);
 319         ret = NULL;
 320     }
 321     BN_CTX_free(ctx);
 322     BN_clear_free(m);
 323     BN_clear_free(kinv);
 324     return ret;
 325 }
 326
 327 /*-
 328  * returns
 329  *      1: correct signature
 330  *      0: incorrect signature
 331  *     -1: error
 332  */
 333 int ossl_ecdsa_verify(int type, const unsigned char *dgst, int dgst_len,
 334                       const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)
 335 {
 336     ECDSA_SIG *s;
 337     const unsigned char *p = sigbuf;
 338     unsigned char *der = NULL;
 339     int derlen = -1;
 340     int ret = -1;
 341
 342     s = ECDSA_SIG_new();
 343     if (s == NULL)
 344         return ret;
 345     if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
 346         goto err;
 347     /* Ensure signature uses DER and doesn't have trailing garbage */
 348     derlen = i2d_ECDSA_SIG(s, &der);
 349     if (derlen != sig_len || memcmp(sigbuf, der, derlen) != 0)
 350         goto err;
 351     ret = ECDSA_do_verify(dgst, dgst_len, s, eckey);
 352  err:
 353     OPENSSL_free(der);
 354     ECDSA_SIG_free(s);
 355     return ret;
 356 }
 357
 358 int ecdsa_simple_verify_sig(const unsigned char *dgst, int dgst_len,
 359                             const ECDSA_SIG *sig, EC_KEY *eckey)
 360 {
 361     int ret = -1, i;
 362     BN_CTX *ctx;
 363     const BIGNUM *order;
 364     BIGNUM *u1, *u2, *m, *X;
 365     EC_POINT *point = NULL;
 366     const EC_GROUP *group;
 367     const EC_POINT *pub_key;
 368
 369     /* check input values */
 370     if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
 371         (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
 372         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, EC_R_MISSING_PARAMETERS);
 373         return -1;
 374     }
 375
 376     if (!EC_KEY_can_sign(eckey)) {
 377         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
 378         return -1;
 379     }
 380
 381     ctx = BN_CTX_new_ex(eckey->libctx);
 382     if (ctx == NULL) {
 383         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
 384         return -1;
 385     }
 386     BN_CTX_start(ctx);
 387     u1 = BN_CTX_get(ctx);
 388     u2 = BN_CTX_get(ctx);
 389     m = BN_CTX_get(ctx);
 390     X = BN_CTX_get(ctx);
 391     if (X == NULL) {
 392         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_BN_LIB);
 393         goto err;
 394     }
 395
 396     order = EC_GROUP_get0_order(group);
 397     if (order == NULL) {
 398         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_EC_LIB);
 399         goto err;
 400     }
 401
 402     if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
 403         BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
 404         BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
 405         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, EC_R_BAD_SIGNATURE);
 406         ret = 0;                /* signature is invalid */
 407         goto err;
 408     }
 409     /* calculate tmp1 = inv(S) mod order */
 410     if (!ec_group_do_inverse_ord(group, u2, sig->s, ctx)) {
 411         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_BN_LIB);
 412         goto err;
 413     }
 414     /* digest -> m */
 415     i = BN_num_bits(order);
 416     /*
 417      * Need to truncate digest if it is too long: first truncate whole bytes.
 418      */
 419     if (8 * dgst_len > i)
 420         dgst_len = (i + 7) / 8;
 421     if (!BN_bin2bn(dgst, dgst_len, m)) {
 422         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_BN_LIB);
 423         goto err;
 424     }
 425     /* If still too long truncate remaining bits with a shift */
 426     if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
 427         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_BN_LIB);
 428         goto err;
 429     }
 430     /* u1 = m * tmp mod order */
 431     if (!BN_mod_mul(u1, m, u2, order, ctx)) {
 432         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_BN_LIB);
 433         goto err;
 434     }
 435     /* u2 = r * w mod q */
 436     if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
 437         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_BN_LIB);
 438         goto err;
 439     }
 440
 441     if ((point = EC_POINT_new(group)) == NULL) {
 442         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
 443         goto err;
 444     }
 445     if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
 446         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_EC_LIB);
 447         goto err;
 448     }
 449
 450     if (!EC_POINT_get_affine_coordinates(group, point, X, NULL, ctx)) {
 451         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_EC_LIB);
 452         goto err;
 453     }
 454
 455     if (!BN_nnmod(u1, X, order, ctx)) {
 456         ECerr(EC_F_ECDSA_SIMPLE_VERIFY_SIG, ERR_R_BN_LIB);
 457         goto err;
 458     }
 459     /*  if the signature is correct u1 is equal to sig->r */
 460     ret = (BN_ucmp(u1, sig->r) == 0);
 461  err:
 462     BN_CTX_end(ctx);
 463     BN_CTX_free(ctx);
 464     EC_POINT_free(point);
 465     return ret;
 466 }