dsa_ossl.c 9.6 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
/* crypto/dsa/dsa_ossl.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

/* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */

#include <stdio.h>
#include "cryptlib.h"
#include <openssl/bn.h>
#include <openssl/dsa.h>
#include <openssl/rand.h>
#include <openssl/asn1.h>
67
#include <openssl/engine.h>
68 69

static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
70
static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94
static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
		  DSA *dsa);
static int dsa_init(DSA *dsa);
static int dsa_finish(DSA *dsa);
static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
		BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
		BN_MONT_CTX *in_mont);
static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
				const BIGNUM *m, BN_CTX *ctx,
				BN_MONT_CTX *m_ctx);

static DSA_METHOD openssl_dsa_meth = {
"OpenSSL DSA method",
dsa_do_sign,
dsa_sign_setup,
dsa_do_verify,
dsa_mod_exp,
dsa_bn_mod_exp,
dsa_init,
dsa_finish,
0,
NULL
};

R
Richard Levitte 已提交
95
const DSA_METHOD *DSA_OpenSSL(void)
96 97 98 99 100 101 102 103 104 105 106 107 108
{
	return &openssl_dsa_meth;
}

static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
	{
	BIGNUM *kinv=NULL,*r=NULL,*s=NULL;
	BIGNUM m;
	BIGNUM xr;
	BN_CTX *ctx=NULL;
	int i,reason=ERR_R_BN_LIB;
	DSA_SIG *ret=NULL;

D
 
Dr. Stephen Henson 已提交
109 110 111 112 113
	if (!dsa->p || !dsa->q || !dsa->g)
		{
		reason=DSA_R_MISSING_PARAMETERS;
		goto err;
		}
114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169
	BN_init(&m);
	BN_init(&xr);
	s=BN_new();
	if (s == NULL) goto err;

	i=BN_num_bytes(dsa->q); /* should be 20 */
	if ((dlen > i) || (dlen > 50))
		{
		reason=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE;
		goto err;
		}

	ctx=BN_CTX_new();
	if (ctx == NULL) goto err;

	if ((dsa->kinv == NULL) || (dsa->r == NULL))
		{
		if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err;
		}
	else
		{
		kinv=dsa->kinv;
		dsa->kinv=NULL;
		r=dsa->r;
		dsa->r=NULL;
		}

	if (BN_bin2bn(dgst,dlen,&m) == NULL) goto err;

	/* Compute  s = inv(k) (m + xr) mod q */
	if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */
	if (!BN_add(s, &xr, &m)) goto err;		/* s = m + xr */
	if (BN_cmp(s,dsa->q) > 0)
		BN_sub(s,s,dsa->q);
	if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err;

	ret=DSA_SIG_new();
	if (ret == NULL) goto err;
	ret->r = r;
	ret->s = s;
	
err:
	if (!ret)
		{
		DSAerr(DSA_F_DSA_DO_SIGN,reason);
		BN_free(r);
		BN_free(s);
		}
	if (ctx != NULL) BN_CTX_free(ctx);
	BN_clear_free(&m);
	BN_clear_free(&xr);
	if (kinv != NULL) /* dsa->kinv is NULL now if we used it */
	    BN_clear_free(kinv);
	return(ret);
	}

170
static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
171 172 173 174 175
	{
	BN_CTX *ctx;
	BIGNUM k,*kinv=NULL,*r=NULL;
	int ret=0;

D
 
Dr. Stephen Henson 已提交
176 177 178 179 180
	if (!dsa->p || !dsa->q || !dsa->g)
		{
		DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS);
		return 0;
		}
181 182 183 184 185 186 187 188 189 190 191 192
	if (ctx_in == NULL)
		{
		if ((ctx=BN_CTX_new()) == NULL) goto err;
		}
	else
		ctx=ctx_in;

	BN_init(&k);
	if ((r=BN_new()) == NULL) goto err;
	kinv=NULL;

	/* Get random k */
193
	do
B
Bodo Möller 已提交
194
		if (!BN_rand_range(&k, dsa->q)) goto err;
195
	while (BN_is_zero(&k));
196 197 198 199 200 201 202 203 204

	if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P))
		{
		if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
			if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p,
				dsa->p,ctx)) goto err;
		}

	/* Compute r = (g^k mod p) mod q */
205
	if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx,
206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237
		(BN_MONT_CTX *)dsa->method_mont_p)) goto err;
	if (!BN_mod(r,r,dsa->q,ctx)) goto err;

	/* Compute  part of 's = inv(k) (m + xr) mod q' */
	if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err;

	if (*kinvp != NULL) BN_clear_free(*kinvp);
	*kinvp=kinv;
	kinv=NULL;
	if (*rp != NULL) BN_clear_free(*rp);
	*rp=r;
	ret=1;
err:
	if (!ret)
		{
		DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB);
		if (kinv != NULL) BN_clear_free(kinv);
		if (r != NULL) BN_clear_free(r);
		}
	if (ctx_in == NULL) BN_CTX_free(ctx);
	if (kinv != NULL) BN_clear_free(kinv);
	BN_clear_free(&k);
	return(ret);
	}

static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
		  DSA *dsa)
	{
	BN_CTX *ctx;
	BIGNUM u1,u2,t1;
	BN_MONT_CTX *mont=NULL;
	int ret = -1;
D
 
Dr. Stephen Henson 已提交
238 239 240 241 242
	if (!dsa->p || !dsa->q || !dsa->g)
		{
		DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS);
		return -1;
		}
243 244 245 246 247 248

	if ((ctx=BN_CTX_new()) == NULL) goto err;
	BN_init(&u1);
	BN_init(&u2);
	BN_init(&t1);

249 250
	if (BN_is_zero(sig->r) || BN_get_sign(sig->r) ||
	    BN_ucmp(sig->r, dsa->q) >= 0)
251 252 253 254
		{
		ret = 0;
		goto err;
		}
255 256
	if (BN_is_zero(sig->s) || BN_get_sign(sig->s) ||
	    BN_ucmp(sig->s, dsa->q) >= 0)
257 258 259 260 261
		{
		ret = 0;
		goto err;
		}

262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300
	/* Calculate W = inv(S) mod Q
	 * save W in u2 */
	if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err;

	/* save M in u1 */
	if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err;

	/* u1 = M * w mod q */
	if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err;

	/* u2 = r * w mod q */
	if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err;

	if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P))
		{
		if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
			if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p,
				dsa->p,ctx)) goto err;
		}
	mont=(BN_MONT_CTX *)dsa->method_mont_p;

#if 0
	{
	BIGNUM t2;

	BN_init(&t2);
	/* v = ( g^u1 * y^u2 mod p ) mod q */
	/* let t1 = g ^ u1 mod p */
	if (!BN_mod_exp_mont(&t1,dsa->g,&u1,dsa->p,ctx,mont)) goto err;
	/* let t2 = y ^ u2 mod p */
	if (!BN_mod_exp_mont(&t2,dsa->pub_key,&u2,dsa->p,ctx,mont)) goto err;
	/* let u1 = t1 * t2 mod p */
	if (!BN_mod_mul(&u1,&t1,&t2,dsa->p,ctx)) goto err_bn;
	BN_free(&t2);
	}
	/* let u1 = u1 mod q */
	if (!BN_mod(&u1,&u1,dsa->q,ctx)) goto err;
#else
	{
301
	if (!dsa->meth->dsa_mod_exp(dsa, &t1,dsa->g,&u1,dsa->pub_key,&u2,
302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322
						dsa->p,ctx,mont)) goto err;
	/* BN_copy(&u1,&t1); */
	/* let u1 = u1 mod q */
	if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err;
	}
#endif
	/* V is now in u1.  If the signature is correct, it will be
	 * equal to R. */
	ret=(BN_ucmp(&u1, sig->r) == 0);

	err:
	if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB);
	if (ctx != NULL) BN_CTX_free(ctx);
	BN_free(&u1);
	BN_free(&u2);
	BN_free(&t1);
	return(ret);
	}

static int dsa_init(DSA *dsa)
{
323
	dsa->flags|=DSA_FLAG_CACHE_MONT_P;
324 325 326 327 328
	return(1);
}

static int dsa_finish(DSA *dsa)
{
329 330
	if(dsa->method_mont_p)
		BN_MONT_CTX_free((BN_MONT_CTX *)dsa->method_mont_p);
331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346
	return(1);
}

static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
		BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
		BN_MONT_CTX *in_mont)
{
	return BN_mod_exp2_mont(rr, a1, p1, a2, p2, m, ctx, in_mont);
}
	
static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
				const BIGNUM *m, BN_CTX *ctx,
				BN_MONT_CTX *m_ctx)
{
	return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
}