text: /* crypto/ecdsa/ecs_ossl.c */
  /*
   * Written by Nils Larsch for the OpenSSL project
   */
  /* ====================================================================
   * Copyright (c) 1998-2004 The OpenSSL Project.  All rights reserved.
   *
   * 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 above 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 acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
   *
   * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
   *    endorse or promote products derived from this software without
   *    prior written permission. For written permission, please contact
   *    openssl-core@OpenSSL.org.
   *
   * 5. Products derived from this software may not be called "OpenSSL"
   *    nor may "OpenSSL" appear in their names without prior written
   *    permission of the OpenSSL Project.
   *
   * 6. Redistributions of any form whatsoever must retain the following
   *    acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
   *
   * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
   * EXPRESSED 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 OpenSSL PROJECT OR
   * ITS 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.
   * ====================================================================
   *
   * This product includes cryptographic software written by Eric Young
   * (eay@cryptsoft.com).  This product includes software written by Tim
   * Hudson (tjh@cryptsoft.com).
   *
   */
  
  #define OPENSSL_FIPSAPI
  
  #include "ecs_locl.h"
  #include <openssl/err.h>
  #include <openssl/obj_mac.h>
  #include <openssl/bn.h>
  
  static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen, 
  		const BIGNUM *, const BIGNUM *, EC_KEY *eckey);
  static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, 
  		BIGNUM **rp);
  static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len, 
  		const ECDSA_SIG *sig, EC_KEY *eckey);
  
  static ECDSA_METHOD openssl_ecdsa_meth = {
  	"OpenSSL ECDSA method",
  	ecdsa_do_sign,
  	ecdsa_sign_setup,
  	ecdsa_do_verify,
  #if 0
  	NULL, /* init     */
  	NULL, /* finish   */
  #endif
  	0,    /* flags    */
  	NULL  /* app_data */
  };
  
  const ECDSA_METHOD *ECDSA_OpenSSL(void)
  {
  	return &openssl_ecdsa_meth;
  }
  
  static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
  		BIGNUM **rp)
  {
  	BN_CTX   *ctx = NULL;
  	BIGNUM	 *k = NULL, *r = NULL, *order = NULL, *X = NULL;
  	EC_POINT *tmp_point=NULL;
  	const EC_GROUP *group;
  	int 	 ret = 0;
  
  	if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
  		return 0;
  	}
  
  	if (ctx_in == NULL) 
  	{
  		if ((ctx = BN_CTX_new()) == NULL)
  		{
  			ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_MALLOC_FAILURE);
  			return 0;
  		}
  	}
  	else
  		ctx = ctx_in;
  
  	k     = BN_new();	/* this value is later returned in *kinvp */
  	r     = BN_new();	/* this value is later returned in *rp    */
  	order = BN_new();
  	X     = BN_new();
  	if (!k || !r || !order || !X)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
  		goto err;
  	}
  	if ((tmp_point = EC_POINT_new(group)) == NULL)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
  		goto err;
  	}
  	if (!EC_GROUP_get_order(group, order, ctx))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
  		goto err;
  	}
  
  #ifdef OPENSSL_FIPS
  	if (!fips_check_ec_prng(eckey))
  		goto err;
  #endif
  	
  	do
  	{
  		/* get random k */	
  		do
  			if (!BN_rand_range(k, order))
  			{
  				ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
  				 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);	
  				goto err;
  			}
  		while (BN_is_zero(k));
  
  		/* compute r the x-coordinate of generator * k */
  		if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx))
  		{
  			ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
  			goto err;
  		}
  		if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
  		{
  			if (!EC_POINT_get_affine_coordinates_GFp(group,
  				tmp_point, X, NULL, ctx))
  			{
  				ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB);
  				goto err;
  			}
  		}
  #ifndef OPENSSL_NO_EC2M
  		else /* NID_X9_62_characteristic_two_field */
  		{
  			if (!EC_POINT_get_affine_coordinates_GF2m(group,
  				tmp_point, X, NULL, ctx))
  			{
  				ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB);
  				goto err;
  			}
  		}
  #endif
  		if (!BN_nnmod(r, X, order, ctx))
  		{
  			ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
  			goto err;
  		}
  	}
  	while (BN_is_zero(r));
  
  	/* compute the inverse of k */
  	if (!BN_mod_inverse(k, k, order, ctx))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
  		goto err;	
  	}
  	/* clear old values if necessary */
  	if (*rp != NULL)
  		BN_clear_free(*rp);
  	if (*kinvp != NULL) 
  		BN_clear_free(*kinvp);
  	/* save the pre-computed values  */
  	*rp    = r;
  	*kinvp = k;
  	ret = 1;
  err:
  	if (!ret)
  	{
  		if (k != NULL) BN_clear_free(k);
  		if (r != NULL) BN_clear_free(r);
  	}
  	if (ctx_in == NULL) 
  		BN_CTX_free(ctx);
  	if (order != NULL)
  		BN_free(order);
  	if (tmp_point != NULL) 
  		EC_POINT_free(tmp_point);
  	if (X)
  		BN_clear_free(X);
  	return(ret);
  }
  
  
  static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len, 
  		const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *eckey)
  {
  	int     ok = 0, i;
  	BIGNUM *kinv=NULL, *s, *m=NULL,*tmp=NULL,*order=NULL;
  	const BIGNUM *ckinv;
  	BN_CTX     *ctx = NULL;
  	const EC_GROUP   *group;
  	ECDSA_SIG  *ret;
  	ECDSA_DATA *ecdsa;
  	const BIGNUM *priv_key;
  
  	ecdsa    = ecdsa_check(eckey);
  	group    = EC_KEY_get0_group(eckey);
  	priv_key = EC_KEY_get0_private_key(eckey);
  	
  	if (group == NULL || priv_key == NULL || ecdsa == NULL)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER);
  		return NULL;
  	}
  
  #ifdef OPENSSL_FIPS
  	if (!fips_check_ec_prng(eckey))
  		return NULL;
  #endif
  
  	ret = ECDSA_SIG_new();
  	if (!ret)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
  		return NULL;
  	}
  	s = ret->s;
  
  	if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL ||
  		(tmp = BN_new()) == NULL || (m = BN_new()) == NULL)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
  		goto err;
  	}
  
  	if (!EC_GROUP_get_order(group, order, ctx))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB);
  		goto err;
  	}
  	i = BN_num_bits(order);
  	/* Need to truncate digest if it is too long: first truncate whole
  	 * bytes.
  	 */
  	if (8 * dgst_len > i)
  		dgst_len = (i + 7)/8;
  	if (!BN_bin2bn(dgst, dgst_len, m))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
  		goto err;
  	}
  	/* If still too long truncate remaining bits with a shift */
  	if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7)))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
  		goto err;
  	}
  	do
  	{
  		if (in_kinv == NULL || in_r == NULL)
  		{
  			if (!ecdsa->meth->ecdsa_sign_setup(eckey, ctx,
  								&kinv, &ret->r))
  			{
  				ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,ERR_R_ECDSA_LIB);
  				goto err;
  			}
  			ckinv = kinv;
  		}
  		else
  		{
  			ckinv  = in_kinv;
  			if (BN_copy(ret->r, in_r) == NULL)
  			{
  				ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
  				goto err;
  			}
  		}
  
  		if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx))
  		{
  			ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
  			goto err;
  		}
  		if (!BN_mod_add_quick(s, tmp, m, order))
  		{
  			ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
  			goto err;
  		}
  		if (!BN_mod_mul(s, s, ckinv, order, ctx))
  		{
  			ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
  			goto err;
  		}
  		if (BN_is_zero(s))
  		{
  			/* if kinv and r have been supplied by the caller
  			 * don't to generate new kinv and r values */
  			if (in_kinv != NULL && in_r != NULL)
  			{
  				ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ECDSA_R_NEED_NEW_SETUP_VALUES);
  				goto err;
  			}
  		}
  		else
  			/* s != 0 => we have a valid signature */
  			break;
  	}
  	while (1);
  
  	ok = 1;
  err:
  	if (!ok)
  	{
  		ECDSA_SIG_free(ret);
  		ret = NULL;
  	}
  	if (ctx)
  		BN_CTX_free(ctx);
  	if (m)
  		BN_clear_free(m);
  	if (tmp)
  		BN_clear_free(tmp);
  	if (order)
  		BN_free(order);
  	if (kinv)
  		BN_clear_free(kinv);
  	return ret;
  }
  
  static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
  		const ECDSA_SIG *sig, EC_KEY *eckey)
  {
  	int ret = -1, i;
  	BN_CTX   *ctx;
  	BIGNUM   *order, *u1, *u2, *m, *X;
  	EC_POINT *point = NULL;
  	const EC_GROUP *group;
  	const EC_POINT *pub_key;
  
  	/* check input values */
  	if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
  	    (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS);
  		return -1;
  	}
  
  	ctx = BN_CTX_new();
  	if (!ctx)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
  		return -1;
  	}
  	BN_CTX_start(ctx);
  	order = BN_CTX_get(ctx);	
  	u1    = BN_CTX_get(ctx);
  	u2    = BN_CTX_get(ctx);
  	m     = BN_CTX_get(ctx);
  	X     = BN_CTX_get(ctx);
  	if (!X)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
  		goto err;
  	}
  	
  	if (!EC_GROUP_get_order(group, order, ctx))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
  		goto err;
  	}
  
  	if (BN_is_zero(sig->r)          || BN_is_negative(sig->r) || 
  	    BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s)  ||
  	    BN_is_negative(sig->s)      || BN_ucmp(sig->s, order) >= 0)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE);
  		ret = 0;	/* signature is invalid */
  		goto err;
  	}
  	/* calculate tmp1 = inv(S) mod order */
  	if (!BN_mod_inverse(u2, sig->s, order, ctx))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
  		goto err;
  	}
  	/* digest -> m */
  	i = BN_num_bits(order);
  	/* Need to truncate digest if it is too long: first truncate whole
  	 * bytes.
  	 */
  	if (8 * dgst_len > i)
  		dgst_len = (i + 7)/8;
  	if (!BN_bin2bn(dgst, dgst_len, m))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
  		goto err;
  	}
  	/* If still too long truncate remaining bits with a shift */
  	if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7)))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
  		goto err;
  	}
  	/* u1 = m * tmp mod order */
  	if (!BN_mod_mul(u1, m, u2, order, ctx))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
  		goto err;
  	}
  	/* u2 = r * w mod q */
  	if (!BN_mod_mul(u2, sig->r, u2, order, ctx))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
  		goto err;
  	}
  
  	if ((point = EC_POINT_new(group)) == NULL)
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
  		goto err;
  	}
  	if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
  		goto err;
  	}
  	if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
  	{
  		if (!EC_POINT_get_affine_coordinates_GFp(group,
  			point, X, NULL, ctx))
  		{
  			ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
  			goto err;
  		}
  	}
  #ifndef OPENSSL_NO_EC2M
  	else /* NID_X9_62_characteristic_two_field */
  	{
  		if (!EC_POINT_get_affine_coordinates_GF2m(group,
  			point, X, NULL, ctx))
  		{
  			ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
  			goto err;
  		}
  	}
  #endif	
  	if (!BN_nnmod(u1, X, order, ctx))
  	{
  		ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
  		goto err;
  	}
  	/*  if the signature is correct u1 is equal to sig->r */
  	ret = (BN_ucmp(u1, sig->r) == 0);
  err:
  	BN_CTX_end(ctx);
  	BN_CTX_free(ctx);
  	if (point)
  		EC_POINT_free(point);
  	return ret;
  }
  
  #ifdef OPENSSL_FIPSCANISTER
  /* FIPS stanadlone version of ecdsa_check: just return FIPS method */
  ECDSA_DATA *fips_ecdsa_check(EC_KEY *key)
  	{
  	static ECDSA_DATA rv = {
  		0,0,0,
  		&openssl_ecdsa_meth
  		};
  	return &rv;
  	}
  /* Standalone digest sign and verify */
  int FIPS_ecdsa_verify_digest(EC_KEY *key,
  			const unsigned char *dig, int dlen, ECDSA_SIG *s)
  	{
  	ECDSA_DATA *ecdsa = ecdsa_check(key);
  	if (ecdsa == NULL)
  		return 0;
  	return ecdsa->meth->ecdsa_do_verify(dig, dlen, s, key);
  	}
  ECDSA_SIG * FIPS_ecdsa_sign_digest(EC_KEY *key,
  					const unsigned char *dig, int dlen)
  	{
  	ECDSA_DATA *ecdsa = ecdsa_check(key);
  	if (ecdsa == NULL)
  		return NULL;
  	return ecdsa->meth->ecdsa_do_sign(dig, dlen, NULL, NULL, key);
  	}
  #endif
  