/* 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> */

 /*

  © Portions copyright (c) 2006 Nokia Corporation.  All rights reserved.

  */

 #include <stdio.h>

 #include "cryptlib.h"

 #include <openssl/bn.h>

 #include <openssl/dsa.h>

 #include <openssl/rand.h>

 #include <openssl/asn1.h>

 #if (defined(SYMBIAN) && (defined(__WINSCW__) || defined(__WINS__)))

 #include "libcrypto_wsd_macros.h"

 #include "libcrypto_wsd.h"

 #endif

 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);

 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);

 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);

 #ifndef EMULATOR

 static DSA_METHOD openssl_dsa_meth = {

 "OpenSSL DSA method",

 dsa_do_sign,

 dsa_sign_setup,

 dsa_do_verify,

 NULL, /* dsa_mod_exp, */

 NULL, /* dsa_bn_mod_exp, */

 dsa_init,

 dsa_finish,

 0,

 NULL,

 NULL,

 NULL

 };

 #else

 GET_STATIC_VAR_FROM_TLS(openssl_dsa_meth,dsa_ossl,DSA_METHOD)

 #define openssl_dsa_meth (*GET_WSD_VAR_NAME(openssl_dsa_meth,dsa_ossl, s)())

 const DSA_METHOD temp_s_openssl_dsa_meth = {

 "OpenSSL DSA method",

 dsa_do_sign,

 dsa_sign_setup,

 dsa_do_verify,

 NULL, /* dsa_mod_exp, */

 NULL, /* dsa_bn_mod_exp, */

 dsa_init,

 dsa_finish,

 0,

 NULL,

 NULL,

 NULL

 };

 #endif

 /* These macro wrappers replace attempts to use the dsa_mod_exp() and

  * bn_mod_exp() handlers in the DSA_METHOD structure. We avoid the problem of

  * having a the macro work as an expression by bundling an "err_instr". So;

  * 

  *     if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx,

  *                 dsa->method_mont_p)) goto err;

  *

  * can be replaced by;

  *

  *     DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, &k, dsa->p, ctx,

  *                 dsa->method_mont_p);

  */

 #define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \

 	do { \

 	int _tmp_res53; \

 	if((dsa)->meth->dsa_mod_exp) \

 		_tmp_res53 = (dsa)->meth->dsa_mod_exp((dsa), (rr), (a1), (p1), \

 				(a2), (p2), (m), (ctx), (in_mont)); \

 	else \

 		_tmp_res53 = BN_mod_exp2_mont((rr), (a1), (p1), (a2), (p2), \

 				(m), (ctx), (in_mont)); \

 	if(!_tmp_res53) err_instr; \

 	} while(0)

 #define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \

 	do { \

 	int _tmp_res53; \

 	if((dsa)->meth->bn_mod_exp) \

 		_tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), (a), (p), \

 				(m), (ctx), (m_ctx)); \

 	else \

 		_tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), (ctx), (m_ctx)); \

 	if(!_tmp_res53) err_instr; \

 	} while(0)

 EXPORT_C const DSA_METHOD *DSA_OpenSSL(void)

 {

 	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;

 	BN_init(&m);

 	BN_init(&xr);

 	if (!dsa->p || !dsa->q || !dsa->g)

 		{

 		reason=DSA_R_MISSING_PARAMETERS;

 		goto err;

 		}

 	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);

 	}

 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)

 	{

 	BN_CTX *ctx;

 	BIGNUM k,kq,*K,*kinv=NULL,*r=NULL;

 	int ret=0;

 	if (!dsa->p || !dsa->q || !dsa->g)

 		{

 		DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS);

 		return 0;

 		}

 	BN_init(&k);

 	BN_init(&kq);

 	if (ctx_in == NULL)

 		{

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

 		}

 	else

 		ctx=ctx_in;

 	if ((r=BN_new()) == NULL) goto err;

 	/* Get random k */

 	do

 		if (!BN_rand_range(&k, dsa->q)) goto err;

 	while (BN_is_zero(&k));

 	if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)

 		{

 		BN_set_flags(&k, BN_FLG_CONSTTIME);

 		}

 	if (dsa->flags & DSA_FLAG_CACHE_MONT_P)

 		{

 		if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p,

 						CRYPTO_LOCK_DSA,

 						dsa->p, ctx))

 			goto err;

 		}

 	/* Compute r = (g^k mod p) mod q */

 	if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)

 		{

 		if (!BN_copy(&kq, &k)) goto err;

 		/* We do not want timing information to leak the length of k,

 		 * so we compute g^k using an equivalent exponent of fixed length.

 		 *

 		 * (This is a kludge that we need because the BN_mod_exp_mont()

 		 * does not let us specify the desired timing behaviour.) */

 		if (!BN_add(&kq, &kq, dsa->q)) goto err;

 		if (BN_num_bits(&kq) <= BN_num_bits(dsa->q))

 			{

 			if (!BN_add(&kq, &kq, dsa->q)) goto err;

 			}

 		K = &kq;

 		}

 	else

 		{

 		K = &k;

 		}

 	DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx,

 			dsa->method_mont_p);

 	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);

 	BN_clear_free(&kq);

 	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;

 	if (!dsa->p || !dsa->q || !dsa->g)

 		{

 		DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS);

 		return -1;

 		}

 	if (BN_num_bits(dsa->q) != 160)

 		{

 		DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_BAD_Q_VALUE);

 		return -1;

 		}

 	if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS)

 		{

 		DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MODULUS_TOO_LARGE);

 		return -1;

 		}

 	BN_init(&u1);

 	BN_init(&u2);

 	BN_init(&t1);

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

 	if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||

 	    BN_ucmp(sig->r, dsa->q) >= 0)

 		{

 		ret = 0;

 		goto err;

 		}

 	if (BN_is_zero(sig->s) || BN_is_negative(sig->s) ||

 	    BN_ucmp(sig->s, dsa->q) >= 0)

 		{

 		ret = 0;

 		goto err;

 		}

 	/* 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->flags & DSA_FLAG_CACHE_MONT_P)

 		{

 		mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p,

 					CRYPTO_LOCK_DSA, dsa->p, ctx);

 		if (!mont)

 			goto err;

 		}

 	DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, ctx, mont);

 	/* BN_copy(&u1,&t1); */

 	/* let u1 = u1 mod q */

 	if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err;

 	/* V is now in u1.  If the signature is correct, it will be

 	 * equal to R. */

 	ret=(BN_ucmp(&u1, sig->r) == 0);

 	err:

 	/* XXX: surely this is wrong - if ret is 0, it just didn't verify;

 	   there is no error in BN. Test should be ret == -1 (Ben) */

 	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)

 {

 	dsa->flags|=DSA_FLAG_CACHE_MONT_P;

 	return(1);

 }

 static int dsa_finish(DSA *dsa)

 {

 	if(dsa->method_mont_p)

 		BN_MONT_CTX_free(dsa->method_mont_p);

 	return(1);

 }