AppleCSP/open_ssl/dsa/dsa_ossl.c

   1 /*
   2  * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 /* crypto/dsa/dsa_ossl.c */
  20 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  21  * All rights reserved.
  22  *
  23  * This package is an SSL implementation written
  24  * by Eric Young (eay@cryptsoft.com).
  25  * The implementation was written so as to conform with Netscapes SSL.
  26  *
  27  * This library is free for commercial and non-commercial use as long as
  28  * the following conditions are aheared to.  The following conditions
  29  * apply to all code found in this distribution, be it the RC4, RSA,
  30  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  31  * included with this distribution is covered by the same copyright terms
  32  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  33  *
  34  * Copyright remains Eric Young's, and as such any Copyright notices in
  35  * the code are not to be removed.
  36  * If this package is used in a product, Eric Young should be given attribution
  37  * as the author of the parts of the library used.
  38  * This can be in the form of a textual message at program startup or
  39  * in documentation (online or textual) provided with the package.
  40  *
  41  * Redistribution and use in source and binary forms, with or without
  42  * modification, are permitted provided that the following conditions
  43  * are met:
  44  * 1. Redistributions of source code must retain the copyright
  45  *    notice, this list of conditions and the following disclaimer.
  46  * 2. Redistributions in binary form must reproduce the above copyright
  47  *    notice, this list of conditions and the following disclaimer in the
  48  *    documentation and/or other materials provided with the distribution.
  49  * 3. All advertising materials mentioning features or use of this software
  50  *    must display the following acknowledgement:
  51  *    "This product includes cryptographic software written by
  52  *     Eric Young (eay@cryptsoft.com)"
  53  *    The word 'cryptographic' can be left out if the rouines from the library
  54  *    being used are not cryptographic related :-).
  55  * 4. If you include any Windows specific code (or a derivative thereof) from
  56  *    the apps directory (application code) you must include an acknowledgement:
  57  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  58  *
  59  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  60  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  61  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  62  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  63  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  64  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  65  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  66  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  67  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  68  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  69  * SUCH DAMAGE.
  70  *
  71  * The licence and distribution terms for any publically available version or
  72  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  73  * copied and put under another distribution licence
  74  * [including the GNU Public Licence.]
  75  */
  76
  77 /* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */
  78
  79 #include <stdio.h>
  80 #include "cryptlib.h"
  81 #include <openssl/bn.h>
  82 #include <openssl/dsa.h>
  83 #include <openssl/rand.h>
  84 #include <openssl/asn1.h>
  85
  86 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
  87 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
  88 static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
  89                   DSA *dsa);
  90 static int dsa_init(DSA *dsa);
  91 static int dsa_finish(DSA *dsa);
  92 static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
  93                 BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
  94                 BN_MONT_CTX *in_mont);
  95 static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
  96                                 const BIGNUM *m, BN_CTX *ctx,
  97                                 BN_MONT_CTX *m_ctx);
  98
  99 static const DSA_METHOD openssl_dsa_meth = {
 100 "OpenSSL DSA method",
 101 dsa_do_sign,
 102 dsa_sign_setup,
 103 dsa_do_verify,
 104 dsa_mod_exp,
 105 dsa_bn_mod_exp,
 106 dsa_init,
 107 dsa_finish,
 108 0,
 109 NULL
 110 };
 111
 112 const DSA_METHOD *DSA_OpenSSL(void)
 113 {
 114         return &openssl_dsa_meth;
 115 }
 116
 117 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
 118         {
 119         BIGNUM *kinv=NULL,*r=NULL,*s=NULL;
 120         BIGNUM m;
 121         BIGNUM xr;
 122         BN_CTX *ctx=NULL;
 123         int i,reason=ERR_R_BN_LIB;
 124         DSA_SIG *ret=NULL;
 125
 126         BN_init(&m);
 127         BN_init(&xr);
 128         s=BN_new();
 129         if (s == NULL) goto err;
 130
 131         i=BN_num_bytes(dsa->q); /* should be 20 */
 132         if ((dlen > i) || (dlen > 50))
 133                 {
 134                 reason=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE;
 135                 goto err;
 136                 }
 137
 138         ctx=BN_CTX_new();
 139         if (ctx == NULL) goto err;
 140
 141         if ((dsa->kinv == NULL) || (dsa->r == NULL))
 142                 {
 143                 if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err;
 144                 }
 145         else
 146                 {
 147                 kinv=dsa->kinv;
 148                 dsa->kinv=NULL;
 149                 r=dsa->r;
 150                 dsa->r=NULL;
 151                 }
 152
 153         if (BN_bin2bn(dgst,dlen,&m) == NULL) goto err;
 154
 155         /* Compute  s = inv(k) (m + xr) mod q */
 156         if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */
 157         if (!BN_add(s, &xr, &m)) goto err;              /* s = m + xr */
 158         if (BN_cmp(s,dsa->q) > 0)
 159                 BN_sub(s,s,dsa->q);
 160         if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err;
 161
 162         ret=DSA_SIG_new();
 163         if (ret == NULL) goto err;
 164         ret->r = r;
 165         ret->s = s;
 166
 167 err:
 168         if (!ret)
 169                 {
 170                 DSAerr(DSA_F_DSA_DO_SIGN,reason);
 171                 BN_free(r);
 172                 BN_free(s);
 173                 }
 174         if (ctx != NULL) BN_CTX_free(ctx);
 175         BN_clear_free(&m);
 176         BN_clear_free(&xr);
 177         if (kinv != NULL) /* dsa->kinv is NULL now if we used it */
 178             BN_clear_free(kinv);
 179         return(ret);
 180         }
 181
 182 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
 183         {
 184         BN_CTX *ctx;
 185         BIGNUM k,*kinv=NULL,*r=NULL;
 186         int ret=0;
 187
 188         if (ctx_in == NULL)
 189                 {
 190                 if ((ctx=BN_CTX_new()) == NULL) goto err;
 191                 }
 192         else
 193                 ctx=ctx_in;
 194
 195         BN_init(&k);
 196         if ((r=BN_new()) == NULL) goto err;
 197         kinv=NULL;
 198
 199         /* Get random k */
 200         for (;;)
 201                 {
 202                 if (!BN_rand(&k, BN_num_bits(dsa->q), 1, 0)) goto err;
 203                 if (BN_cmp(&k,dsa->q) >= 0)
 204                         BN_sub(&k,&k,dsa->q);
 205                 if (!BN_is_zero(&k)) break;
 206                 }
 207
 208         if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P))
 209                 {
 210                 if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
 211                         if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p,
 212                                 dsa->p,ctx)) goto err;
 213                 }
 214
 215         /* Compute r = (g^k mod p) mod q */
 216         if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx,
 217                 (BN_MONT_CTX *)dsa->method_mont_p)) goto err;
 218         if (!BN_mod(r,r,dsa->q,ctx)) goto err;
 219
 220         /* Compute  part of 's = inv(k) (m + xr) mod q' */
 221         if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err;
 222
 223         if (*kinvp != NULL) BN_clear_free(*kinvp);
 224         *kinvp=kinv;
 225         kinv=NULL;
 226         if (*rp != NULL) BN_clear_free(*rp);
 227         *rp=r;
 228         ret=1;
 229 err:
 230         if (!ret)
 231                 {
 232                 DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB);
 233                 if (kinv != NULL) BN_clear_free(kinv);
 234                 if (r != NULL) BN_clear_free(r);
 235                 }
 236         if (ctx_in == NULL) BN_CTX_free(ctx);
 237         if (kinv != NULL) BN_clear_free(kinv);
 238         BN_clear_free(&k);
 239         return(ret);
 240         }
 241
 242 static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
 243                   DSA *dsa)
 244         {
 245         BN_CTX *ctx;
 246         BIGNUM u1,u2,t1;
 247         BN_MONT_CTX *mont=NULL;
 248         int ret = -1;
 249
 250         if ((ctx=BN_CTX_new()) == NULL) goto err;
 251         BN_init(&u1);
 252         BN_init(&u2);
 253         BN_init(&t1);
 254
 255         /* Calculate W = inv(S) mod Q
 256          * save W in u2 */
 257         if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err;
 258
 259         /* save M in u1 */
 260         if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err;
 261
 262         /* u1 = M * w mod q */
 263         if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err;
 264
 265         /* u2 = r * w mod q */
 266         if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err;
 267
 268         if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P))
 269                 {
 270                 if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
 271                         if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p,
 272                                 dsa->p,ctx)) goto err;
 273                 }
 274         mont=(BN_MONT_CTX *)dsa->method_mont_p;
 275
 276 #if 0
 277         {
 278         BIGNUM t2;
 279
 280         BN_init(&t2);
 281         /* v = ( g^u1 * y^u2 mod p ) mod q */
 282         /* let t1 = g ^ u1 mod p */
 283         if (!BN_mod_exp_mont(&t1,dsa->g,&u1,dsa->p,ctx,mont)) goto err;
 284         /* let t2 = y ^ u2 mod p */
 285         if (!BN_mod_exp_mont(&t2,dsa->pub_key,&u2,dsa->p,ctx,mont)) goto err;
 286         /* let u1 = t1 * t2 mod p */
 287         if (!BN_mod_mul(&u1,&t1,&t2,dsa->p,ctx)) goto err_bn;
 288         BN_free(&t2);
 289         }
 290         /* let u1 = u1 mod q */
 291         if (!BN_mod(&u1,&u1,dsa->q,ctx)) goto err;
 292 #else
 293         {
 294         if (!dsa->meth->dsa_mod_exp(dsa, &t1,dsa->g,&u1,dsa->pub_key,&u2,
 295                                                 dsa->p,ctx,mont)) goto err;
 296         /* BN_copy(&u1,&t1); */
 297         /* let u1 = u1 mod q */
 298         if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err;
 299         }
 300 #endif
 301         /* V is now in u1.  If the signature is correct, it will be
 302          * equal to R. */
 303         ret=(BN_ucmp(&u1, sig->r) == 0);
 304
 305         err:
 306         if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB);
 307         if (ctx != NULL) BN_CTX_free(ctx);
 308         BN_free(&u1);
 309         BN_free(&u2);
 310         BN_free(&t1);
 311         return(ret);
 312         }
 313
 314 static int dsa_init(DSA *dsa)
 315 {
 316         dsa->flags|=DSA_FLAG_CACHE_MONT_P;
 317         return(1);
 318 }
 319
 320 static int dsa_finish(DSA *dsa)
 321 {
 322         if(dsa->method_mont_p)
 323                 BN_MONT_CTX_free((BN_MONT_CTX *)dsa->method_mont_p);
 324         return(1);
 325 }
 326
 327 static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
 328                 BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
 329                 BN_MONT_CTX *in_mont)
 330 {
 331         return BN_mod_exp2_mont(rr, a1, p1, a2, p2, m, ctx, in_mont);
 332 }
 333
 334 static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
 335                                 const BIGNUM *m, BN_CTX *ctx,
 336                                 BN_MONT_CTX *m_ctx)
 337 {
 338         return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
 339 }