sl@0: /* crypto/dsa/dsa_ossl.c */
sl@0: /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
sl@0:  * All rights reserved.
sl@0:  *
sl@0:  * This package is an SSL implementation written
sl@0:  * by Eric Young (eay@cryptsoft.com).
sl@0:  * The implementation was written so as to conform with Netscapes SSL.
sl@0:  * 
sl@0:  * This library is free for commercial and non-commercial use as long as
sl@0:  * the following conditions are aheared to.  The following conditions
sl@0:  * apply to all code found in this distribution, be it the RC4, RSA,
sl@0:  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
sl@0:  * included with this distribution is covered by the same copyright terms
sl@0:  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
sl@0:  * 
sl@0:  * Copyright remains Eric Young's, and as such any Copyright notices in
sl@0:  * the code are not to be removed.
sl@0:  * If this package is used in a product, Eric Young should be given attribution
sl@0:  * as the author of the parts of the library used.
sl@0:  * This can be in the form of a textual message at program startup or
sl@0:  * in documentation (online or textual) provided with the package.
sl@0:  * 
sl@0:  * Redistribution and use in source and binary forms, with or without
sl@0:  * modification, are permitted provided that the following conditions
sl@0:  * are met:
sl@0:  * 1. Redistributions of source code must retain the copyright
sl@0:  *    notice, this list of conditions and the following disclaimer.
sl@0:  * 2. Redistributions in binary form must reproduce the above copyright
sl@0:  *    notice, this list of conditions and the following disclaimer in the
sl@0:  *    documentation and/or other materials provided with the distribution.
sl@0:  * 3. All advertising materials mentioning features or use of this software
sl@0:  *    must display the following acknowledgement:
sl@0:  *    "This product includes cryptographic software written by
sl@0:  *     Eric Young (eay@cryptsoft.com)"
sl@0:  *    The word 'cryptographic' can be left out if the rouines from the library
sl@0:  *    being used are not cryptographic related :-).
sl@0:  * 4. If you include any Windows specific code (or a derivative thereof) from 
sl@0:  *    the apps directory (application code) you must include an acknowledgement:
sl@0:  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
sl@0:  * 
sl@0:  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
sl@0:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
sl@0:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
sl@0:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
sl@0:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
sl@0:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
sl@0:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
sl@0:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
sl@0:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
sl@0:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
sl@0:  * SUCH DAMAGE.
sl@0:  * 
sl@0:  * The licence and distribution terms for any publically available version or
sl@0:  * derivative of this code cannot be changed.  i.e. this code cannot simply be
sl@0:  * copied and put under another distribution licence
sl@0:  * [including the GNU Public Licence.]
sl@0:  */
sl@0: 
sl@0: /* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */
sl@0: /*
sl@0:  © Portions copyright (c) 2006 Nokia Corporation.  All rights reserved.
sl@0:  */
sl@0: 
sl@0: #include <stdio.h>
sl@0: #include "cryptlib.h"
sl@0: #include <openssl/bn.h>
sl@0: #include <openssl/dsa.h>
sl@0: #include <openssl/rand.h>
sl@0: #include <openssl/asn1.h>
sl@0: #if (defined(SYMBIAN) && (defined(__WINSCW__) || defined(__WINS__)))
sl@0: #include "libcrypto_wsd_macros.h"
sl@0: #include "libcrypto_wsd.h"
sl@0: #endif
sl@0: 
sl@0: static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
sl@0: static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
sl@0: static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
sl@0: 		  DSA *dsa);
sl@0: static int dsa_init(DSA *dsa);
sl@0: static int dsa_finish(DSA *dsa);
sl@0: 
sl@0: #ifndef EMULATOR
sl@0: static DSA_METHOD openssl_dsa_meth = {
sl@0: "OpenSSL DSA method",
sl@0: dsa_do_sign,
sl@0: dsa_sign_setup,
sl@0: dsa_do_verify,
sl@0: NULL, /* dsa_mod_exp, */
sl@0: NULL, /* dsa_bn_mod_exp, */
sl@0: dsa_init,
sl@0: dsa_finish,
sl@0: 0,
sl@0: NULL,
sl@0: NULL,
sl@0: NULL
sl@0: };
sl@0: #else
sl@0: GET_STATIC_VAR_FROM_TLS(openssl_dsa_meth,dsa_ossl,DSA_METHOD)
sl@0: #define openssl_dsa_meth (*GET_WSD_VAR_NAME(openssl_dsa_meth,dsa_ossl, s)())
sl@0: const DSA_METHOD temp_s_openssl_dsa_meth = {
sl@0: "OpenSSL DSA method",
sl@0: dsa_do_sign,
sl@0: dsa_sign_setup,
sl@0: dsa_do_verify,
sl@0: NULL, /* dsa_mod_exp, */
sl@0: NULL, /* dsa_bn_mod_exp, */
sl@0: dsa_init,
sl@0: dsa_finish,
sl@0: 0,
sl@0: NULL,
sl@0: NULL,
sl@0: NULL
sl@0: };
sl@0: #endif
sl@0: 
sl@0: /* These macro wrappers replace attempts to use the dsa_mod_exp() and
sl@0:  * bn_mod_exp() handlers in the DSA_METHOD structure. We avoid the problem of
sl@0:  * having a the macro work as an expression by bundling an "err_instr". So;
sl@0:  * 
sl@0:  *     if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx,
sl@0:  *                 dsa->method_mont_p)) goto err;
sl@0:  *
sl@0:  * can be replaced by;
sl@0:  *
sl@0:  *     DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, &k, dsa->p, ctx,
sl@0:  *                 dsa->method_mont_p);
sl@0:  */
sl@0: 
sl@0: #define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \
sl@0: 	do { \
sl@0: 	int _tmp_res53; \
sl@0: 	if((dsa)->meth->dsa_mod_exp) \
sl@0: 		_tmp_res53 = (dsa)->meth->dsa_mod_exp((dsa), (rr), (a1), (p1), \
sl@0: 				(a2), (p2), (m), (ctx), (in_mont)); \
sl@0: 	else \
sl@0: 		_tmp_res53 = BN_mod_exp2_mont((rr), (a1), (p1), (a2), (p2), \
sl@0: 				(m), (ctx), (in_mont)); \
sl@0: 	if(!_tmp_res53) err_instr; \
sl@0: 	} while(0)
sl@0: #define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \
sl@0: 	do { \
sl@0: 	int _tmp_res53; \
sl@0: 	if((dsa)->meth->bn_mod_exp) \
sl@0: 		_tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), (a), (p), \
sl@0: 				(m), (ctx), (m_ctx)); \
sl@0: 	else \
sl@0: 		_tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), (ctx), (m_ctx)); \
sl@0: 	if(!_tmp_res53) err_instr; \
sl@0: 	} while(0)
sl@0: 
sl@0: EXPORT_C const DSA_METHOD *DSA_OpenSSL(void)
sl@0: {
sl@0: 	return &openssl_dsa_meth;
sl@0: }
sl@0: 
sl@0: static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
sl@0: 	{
sl@0: 	BIGNUM *kinv=NULL,*r=NULL,*s=NULL;
sl@0: 	BIGNUM m;
sl@0: 	BIGNUM xr;
sl@0: 	BN_CTX *ctx=NULL;
sl@0: 	int i,reason=ERR_R_BN_LIB;
sl@0: 	DSA_SIG *ret=NULL;
sl@0: 
sl@0: 	BN_init(&m);
sl@0: 	BN_init(&xr);
sl@0: 
sl@0: 	if (!dsa->p || !dsa->q || !dsa->g)
sl@0: 		{
sl@0: 		reason=DSA_R_MISSING_PARAMETERS;
sl@0: 		goto err;
sl@0: 		}
sl@0: 
sl@0: 	s=BN_new();
sl@0: 	if (s == NULL) goto err;
sl@0: 
sl@0: 	i=BN_num_bytes(dsa->q); /* should be 20 */
sl@0: 	if ((dlen > i) || (dlen > 50))
sl@0: 		{
sl@0: 		reason=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE;
sl@0: 		goto err;
sl@0: 		}
sl@0: 
sl@0: 	ctx=BN_CTX_new();
sl@0: 	if (ctx == NULL) goto err;
sl@0: 
sl@0: 	if ((dsa->kinv == NULL) || (dsa->r == NULL))
sl@0: 		{
sl@0: 		if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err;
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		kinv=dsa->kinv;
sl@0: 		dsa->kinv=NULL;
sl@0: 		r=dsa->r;
sl@0: 		dsa->r=NULL;
sl@0: 		}
sl@0: 
sl@0: 	if (BN_bin2bn(dgst,dlen,&m) == NULL) goto err;
sl@0: 
sl@0: 	/* Compute  s = inv(k) (m + xr) mod q */
sl@0: 	if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */
sl@0: 	if (!BN_add(s, &xr, &m)) goto err;		/* s = m + xr */
sl@0: 	if (BN_cmp(s,dsa->q) > 0)
sl@0: 		BN_sub(s,s,dsa->q);
sl@0: 	if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err;
sl@0: 
sl@0: 	ret=DSA_SIG_new();
sl@0: 	if (ret == NULL) goto err;
sl@0: 	ret->r = r;
sl@0: 	ret->s = s;
sl@0: 	
sl@0: err:
sl@0: 	if (!ret)
sl@0: 		{
sl@0: 		DSAerr(DSA_F_DSA_DO_SIGN,reason);
sl@0: 		BN_free(r);
sl@0: 		BN_free(s);
sl@0: 		}
sl@0: 	if (ctx != NULL) BN_CTX_free(ctx);
sl@0: 	BN_clear_free(&m);
sl@0: 	BN_clear_free(&xr);
sl@0: 	if (kinv != NULL) /* dsa->kinv is NULL now if we used it */
sl@0: 	    BN_clear_free(kinv);
sl@0: 	return(ret);
sl@0: 	}
sl@0: 
sl@0: static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
sl@0: 	{
sl@0: 	BN_CTX *ctx;
sl@0: 	BIGNUM k,kq,*K,*kinv=NULL,*r=NULL;
sl@0: 	int ret=0;
sl@0: 
sl@0: 	if (!dsa->p || !dsa->q || !dsa->g)
sl@0: 		{
sl@0: 		DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS);
sl@0: 		return 0;
sl@0: 		}
sl@0: 
sl@0: 	BN_init(&k);
sl@0: 	BN_init(&kq);
sl@0: 
sl@0: 	if (ctx_in == NULL)
sl@0: 		{
sl@0: 		if ((ctx=BN_CTX_new()) == NULL) goto err;
sl@0: 		}
sl@0: 	else
sl@0: 		ctx=ctx_in;
sl@0: 
sl@0: 	if ((r=BN_new()) == NULL) goto err;
sl@0: 
sl@0: 	/* Get random k */
sl@0: 	do
sl@0: 		if (!BN_rand_range(&k, dsa->q)) goto err;
sl@0: 	while (BN_is_zero(&k));
sl@0: 	if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
sl@0: 		{
sl@0: 		BN_set_flags(&k, BN_FLG_CONSTTIME);
sl@0: 		}
sl@0: 
sl@0: 	if (dsa->flags & DSA_FLAG_CACHE_MONT_P)
sl@0: 		{
sl@0: 		if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p,
sl@0: 						CRYPTO_LOCK_DSA,
sl@0: 						dsa->p, ctx))
sl@0: 			goto err;
sl@0: 		}
sl@0: 
sl@0: 	/* Compute r = (g^k mod p) mod q */
sl@0: 
sl@0: 	if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
sl@0: 		{
sl@0: 		if (!BN_copy(&kq, &k)) goto err;
sl@0: 
sl@0: 		/* We do not want timing information to leak the length of k,
sl@0: 		 * so we compute g^k using an equivalent exponent of fixed length.
sl@0: 		 *
sl@0: 		 * (This is a kludge that we need because the BN_mod_exp_mont()
sl@0: 		 * does not let us specify the desired timing behaviour.) */
sl@0: 
sl@0: 		if (!BN_add(&kq, &kq, dsa->q)) goto err;
sl@0: 		if (BN_num_bits(&kq) <= BN_num_bits(dsa->q))
sl@0: 			{
sl@0: 			if (!BN_add(&kq, &kq, dsa->q)) goto err;
sl@0: 			}
sl@0: 
sl@0: 		K = &kq;
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		K = &k;
sl@0: 		}
sl@0: 	DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx,
sl@0: 			dsa->method_mont_p);
sl@0: 	if (!BN_mod(r,r,dsa->q,ctx)) goto err;
sl@0: 
sl@0: 	/* Compute  part of 's = inv(k) (m + xr) mod q' */
sl@0: 	if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err;
sl@0: 
sl@0: 	if (*kinvp != NULL) BN_clear_free(*kinvp);
sl@0: 	*kinvp=kinv;
sl@0: 	kinv=NULL;
sl@0: 	if (*rp != NULL) BN_clear_free(*rp);
sl@0: 	*rp=r;
sl@0: 	ret=1;
sl@0: err:
sl@0: 	if (!ret)
sl@0: 		{
sl@0: 		DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB);
sl@0: 		if (kinv != NULL) BN_clear_free(kinv);
sl@0: 		if (r != NULL) BN_clear_free(r);
sl@0: 		}
sl@0: 	if (ctx_in == NULL) BN_CTX_free(ctx);
sl@0: 	if (kinv != NULL) BN_clear_free(kinv);
sl@0: 	BN_clear_free(&k);
sl@0: 	BN_clear_free(&kq);
sl@0: 	return(ret);
sl@0: 	}
sl@0: 
sl@0: static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
sl@0: 		  DSA *dsa)
sl@0: 	{
sl@0: 	BN_CTX *ctx;
sl@0: 	BIGNUM u1,u2,t1;
sl@0: 	BN_MONT_CTX *mont=NULL;
sl@0: 	int ret = -1;
sl@0: 	if (!dsa->p || !dsa->q || !dsa->g)
sl@0: 		{
sl@0: 		DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS);
sl@0: 		return -1;
sl@0: 		}
sl@0: 
sl@0: 	if (BN_num_bits(dsa->q) != 160)
sl@0: 		{
sl@0: 		DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_BAD_Q_VALUE);
sl@0: 		return -1;
sl@0: 		}
sl@0: 
sl@0: 	if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS)
sl@0: 		{
sl@0: 		DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MODULUS_TOO_LARGE);
sl@0: 		return -1;
sl@0: 		}
sl@0: 
sl@0: 	BN_init(&u1);
sl@0: 	BN_init(&u2);
sl@0: 	BN_init(&t1);
sl@0: 
sl@0: 	if ((ctx=BN_CTX_new()) == NULL) goto err;
sl@0: 
sl@0: 	if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
sl@0: 	    BN_ucmp(sig->r, dsa->q) >= 0)
sl@0: 		{
sl@0: 		ret = 0;
sl@0: 		goto err;
sl@0: 		}
sl@0: 	if (BN_is_zero(sig->s) || BN_is_negative(sig->s) ||
sl@0: 	    BN_ucmp(sig->s, dsa->q) >= 0)
sl@0: 		{
sl@0: 		ret = 0;
sl@0: 		goto err;
sl@0: 		}
sl@0: 
sl@0: 	/* Calculate W = inv(S) mod Q
sl@0: 	 * save W in u2 */
sl@0: 	if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err;
sl@0: 
sl@0: 	/* save M in u1 */
sl@0: 	if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err;
sl@0: 
sl@0: 	/* u1 = M * w mod q */
sl@0: 	if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err;
sl@0: 
sl@0: 	/* u2 = r * w mod q */
sl@0: 	if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err;
sl@0: 
sl@0: 
sl@0: 	if (dsa->flags & DSA_FLAG_CACHE_MONT_P)
sl@0: 		{
sl@0: 		mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p,
sl@0: 					CRYPTO_LOCK_DSA, dsa->p, ctx);
sl@0: 		if (!mont)
sl@0: 			goto err;
sl@0: 		}
sl@0: 
sl@0: 
sl@0: 	DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, ctx, mont);
sl@0: 	/* BN_copy(&u1,&t1); */
sl@0: 	/* let u1 = u1 mod q */
sl@0: 	if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err;
sl@0: 
sl@0: 	/* V is now in u1.  If the signature is correct, it will be
sl@0: 	 * equal to R. */
sl@0: 	ret=(BN_ucmp(&u1, sig->r) == 0);
sl@0: 
sl@0: 	err:
sl@0: 	/* XXX: surely this is wrong - if ret is 0, it just didn't verify;
sl@0: 	   there is no error in BN. Test should be ret == -1 (Ben) */
sl@0: 	if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB);
sl@0: 	if (ctx != NULL) BN_CTX_free(ctx);
sl@0: 	BN_free(&u1);
sl@0: 	BN_free(&u2);
sl@0: 	BN_free(&t1);
sl@0: 	return(ret);
sl@0: 	}
sl@0: 
sl@0: static int dsa_init(DSA *dsa)
sl@0: {
sl@0: 	dsa->flags|=DSA_FLAG_CACHE_MONT_P;
sl@0: 	return(1);
sl@0: }
sl@0: 
sl@0: static int dsa_finish(DSA *dsa)
sl@0: {
sl@0: 	if(dsa->method_mont_p)
sl@0: 		BN_MONT_CTX_free(dsa->method_mont_p);
sl@0: 	return(1);
sl@0: }
sl@0: