crypto/openssl-0.9.7d/crypto/dsa/dsa_ossl.c

   1 /* crypto/dsa/dsa_ossl.c */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59 /* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */
  60
  61 #include <stdio.h>
  62 #include "cryptlib.h"
  63 #include <openssl/bn.h>
  64 #include <openssl/dsa.h>
  65 #include <openssl/rand.h>
  66 #include <openssl/asn1.h>
  67
  68 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
  69 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
  70 static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
  71                   DSA *dsa);
  72 static int dsa_init(DSA *dsa);
  73 static int dsa_finish(DSA *dsa);
  74 static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
  75                 BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
  76                 BN_MONT_CTX *in_mont);
  77 static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
  78                                 const BIGNUM *m, BN_CTX *ctx,
  79                                 BN_MONT_CTX *m_ctx);
  80
  81 static DSA_METHOD openssl_dsa_meth = {
  82 "OpenSSL DSA method",
  83 dsa_do_sign,
  84 dsa_sign_setup,
  85 dsa_do_verify,
  86 dsa_mod_exp,
  87 dsa_bn_mod_exp,
  88 dsa_init,
  89 dsa_finish,
  90 0,
  91 NULL
  92 };
  93
  94 const DSA_METHOD *DSA_OpenSSL(void)
  95 {
  96         return &openssl_dsa_meth;
  97 }
  98
  99 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
 100         {
 101         BIGNUM *kinv=NULL,*r=NULL,*s=NULL;
 102         BIGNUM m;
 103         BIGNUM xr;
 104         BN_CTX *ctx=NULL;
 105         int i,reason=ERR_R_BN_LIB;
 106         DSA_SIG *ret=NULL;
 107
 108         BN_init(&m);
 109         BN_init(&xr);
 110
 111         if (!dsa->p || !dsa->q || !dsa->g)
 112                 {
 113                 reason=DSA_R_MISSING_PARAMETERS;
 114                 goto err;
 115                 }
 116
 117         s=BN_new();
 118         if (s == NULL) goto err;
 119
 120         i=BN_num_bytes(dsa->q); /* should be 20 */
 121         if ((dlen > i) || (dlen > 50))
 122                 {
 123                 reason=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE;
 124                 goto err;
 125                 }
 126
 127         ctx=BN_CTX_new();
 128         if (ctx == NULL) goto err;
 129
 130         if ((dsa->kinv == NULL) || (dsa->r == NULL))
 131                 {
 132                 if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err;
 133                 }
 134         else
 135                 {
 136                 kinv=dsa->kinv;
 137                 dsa->kinv=NULL;
 138                 r=dsa->r;
 139                 dsa->r=NULL;
 140                 }
 141
 142         if (BN_bin2bn(dgst,dlen,&m) == NULL) goto err;
 143
 144         /* Compute  s = inv(k) (m + xr) mod q */
 145         if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */
 146         if (!BN_add(s, &xr, &m)) goto err;              /* s = m + xr */
 147         if (BN_cmp(s,dsa->q) > 0)
 148                 BN_sub(s,s,dsa->q);
 149         if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err;
 150
 151         ret=DSA_SIG_new();
 152         if (ret == NULL) goto err;
 153         ret->r = r;
 154         ret->s = s;
 155
 156 err:
 157         if (!ret)
 158                 {
 159                 DSAerr(DSA_F_DSA_DO_SIGN,reason);
 160                 BN_free(r);
 161                 BN_free(s);
 162                 }
 163         if (ctx != NULL) BN_CTX_free(ctx);
 164         BN_clear_free(&m);
 165         BN_clear_free(&xr);
 166         if (kinv != NULL) /* dsa->kinv is NULL now if we used it */
 167             BN_clear_free(kinv);
 168         return(ret);
 169         }
 170
 171 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
 172         {
 173         BN_CTX *ctx;
 174         BIGNUM k,*kinv=NULL,*r=NULL;
 175         int ret=0;
 176
 177         if (!dsa->p || !dsa->q || !dsa->g)
 178                 {
 179                 DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS);
 180                 return 0;
 181                 }
 182
 183         BN_init(&k);
 184
 185         if (ctx_in == NULL)
 186                 {
 187                 if ((ctx=BN_CTX_new()) == NULL) goto err;
 188                 }
 189         else
 190                 ctx=ctx_in;
 191
 192         if ((r=BN_new()) == NULL) goto err;
 193         kinv=NULL;
 194
 195         /* Get random k */
 196         do
 197                 if (!BN_rand_range(&k, dsa->q)) goto err;
 198         while (BN_is_zero(&k));
 199
 200         if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P))
 201                 {
 202                 if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
 203                         if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p,
 204                                 dsa->p,ctx)) goto err;
 205                 }
 206
 207         /* Compute r = (g^k mod p) mod q */
 208         if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx,
 209                 (BN_MONT_CTX *)dsa->method_mont_p)) goto err;
 210         if (!BN_mod(r,r,dsa->q,ctx)) goto err;
 211
 212         /* Compute  part of 's = inv(k) (m + xr) mod q' */
 213         if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err;
 214
 215         if (*kinvp != NULL) BN_clear_free(*kinvp);
 216         *kinvp=kinv;
 217         kinv=NULL;
 218         if (*rp != NULL) BN_clear_free(*rp);
 219         *rp=r;
 220         ret=1;
 221 err:
 222         if (!ret)
 223                 {
 224                 DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB);
 225                 if (kinv != NULL) BN_clear_free(kinv);
 226                 if (r != NULL) BN_clear_free(r);
 227                 }
 228         if (ctx_in == NULL) BN_CTX_free(ctx);
 229         if (kinv != NULL) BN_clear_free(kinv);
 230         BN_clear_free(&k);
 231         return(ret);
 232         }
 233
 234 static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
 235                   DSA *dsa)
 236         {
 237         BN_CTX *ctx;
 238         BIGNUM u1,u2,t1;
 239         BN_MONT_CTX *mont=NULL;
 240         int ret = -1;
 241         if (!dsa->p || !dsa->q || !dsa->g)
 242                 {
 243                 DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS);
 244                 return -1;
 245                 }
 246
 247         BN_init(&u1);
 248         BN_init(&u2);
 249         BN_init(&t1);
 250
 251         if ((ctx=BN_CTX_new()) == NULL) goto err;
 252
 253         if (BN_is_zero(sig->r) || sig->r->neg || BN_ucmp(sig->r, dsa->q) >= 0)
 254                 {
 255                 ret = 0;
 256                 goto err;
 257                 }
 258         if (BN_is_zero(sig->s) || sig->s->neg || BN_ucmp(sig->s, dsa->q) >= 0)
 259                 {
 260                 ret = 0;
 261                 goto err;
 262                 }
 263
 264         /* Calculate W = inv(S) mod Q
 265          * save W in u2 */
 266         if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err;
 267
 268         /* save M in u1 */
 269         if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err;
 270
 271         /* u1 = M * w mod q */
 272         if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err;
 273
 274         /* u2 = r * w mod q */
 275         if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err;
 276
 277         if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P))
 278                 {
 279                 if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
 280                         if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p,
 281                                 dsa->p,ctx)) goto err;
 282                 }
 283         mont=(BN_MONT_CTX *)dsa->method_mont_p;
 284
 285 #if 0
 286         {
 287         BIGNUM t2;
 288
 289         BN_init(&t2);
 290         /* v = ( g^u1 * y^u2 mod p ) mod q */
 291         /* let t1 = g ^ u1 mod p */
 292         if (!BN_mod_exp_mont(&t1,dsa->g,&u1,dsa->p,ctx,mont)) goto err;
 293         /* let t2 = y ^ u2 mod p */
 294         if (!BN_mod_exp_mont(&t2,dsa->pub_key,&u2,dsa->p,ctx,mont)) goto err;
 295         /* let u1 = t1 * t2 mod p */
 296         if (!BN_mod_mul(&u1,&t1,&t2,dsa->p,ctx)) goto err_bn;
 297         BN_free(&t2);
 298         }
 299         /* let u1 = u1 mod q */
 300         if (!BN_mod(&u1,&u1,dsa->q,ctx)) goto err;
 301 #else
 302         {
 303         if (!dsa->meth->dsa_mod_exp(dsa, &t1,dsa->g,&u1,dsa->pub_key,&u2,
 304                                                 dsa->p,ctx,mont)) goto err;
 305         /* BN_copy(&u1,&t1); */
 306         /* let u1 = u1 mod q */
 307         if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err;
 308         }
 309 #endif
 310         /* V is now in u1.  If the signature is correct, it will be
 311          * equal to R. */
 312         ret=(BN_ucmp(&u1, sig->r) == 0);
 313
 314         err:
 315         if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB);
 316         if (ctx != NULL) BN_CTX_free(ctx);
 317         BN_free(&u1);
 318         BN_free(&u2);
 319         BN_free(&t1);
 320         return(ret);
 321         }
 322
 323 static int dsa_init(DSA *dsa)
 324 {
 325         dsa->flags|=DSA_FLAG_CACHE_MONT_P;
 326         return(1);
 327 }
 328
 329 static int dsa_finish(DSA *dsa)
 330 {
 331         if(dsa->method_mont_p)
 332                 BN_MONT_CTX_free((BN_MONT_CTX *)dsa->method_mont_p);
 333         return(1);
 334 }
 335
 336 static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
 337                 BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
 338                 BN_MONT_CTX *in_mont)
 339 {
 340         return BN_mod_exp2_mont(rr, a1, p1, a2, p2, m, ctx, in_mont);
 341 }
 342
 343 static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
 344                                 const BIGNUM *m, BN_CTX *ctx,
 345                                 BN_MONT_CTX *m_ctx)
 346 {
 347         return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
 348 }