text: /* crypto/dsa/dsa_lib.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/asn1.h>
  #ifndef OPENSSL_NO_ENGINE
  #include <openssl/engine.h>
  #endif
  #ifndef OPENSSL_NO_DH
  #include <openssl/dh.h>
  #endif
  
  const char DSA_version[]="DSA" OPENSSL_VERSION_PTEXT;
  
  static const DSA_METHOD *default_DSA_method = NULL;
  
  void DSA_set_default_method(const DSA_METHOD *meth)
  	{
  	default_DSA_method = meth;
  	}
  
  const DSA_METHOD *DSA_get_default_method(void)
  	{
  	if(!default_DSA_method)
  		default_DSA_method = DSA_OpenSSL();
  	return default_DSA_method;
  	}
  
  DSA *DSA_new(void)
  	{
  	return DSA_new_method(NULL);
  	}
  
  int DSA_set_method(DSA *dsa, const DSA_METHOD *meth)
  	{
  	/* NB: The caller is specifically setting a method, so it's not up to us
  	 * to deal with which ENGINE it comes from. */
          const DSA_METHOD *mtmp;
          mtmp = dsa->meth;
          if (mtmp->finish) mtmp->finish(dsa);
  #ifndef OPENSSL_NO_ENGINE
  	if (dsa->engine)
  		{
  		ENGINE_finish(dsa->engine);
  		dsa->engine = NULL;
  		}
  #endif
          dsa->meth = meth;
          if (meth->init) meth->init(dsa);
          return 1;
  	}
  
  DSA *DSA_new_method(ENGINE *engine)
  	{
  	DSA *ret;
  
  	ret=(DSA *)OPENSSL_malloc(sizeof(DSA));
  	if (ret == NULL)
  		{
  		DSAerr(DSA_F_DSA_NEW_METHOD,ERR_R_MALLOC_FAILURE);
  		return(NULL);
  		}
  	ret->meth = DSA_get_default_method();
  #ifndef OPENSSL_NO_ENGINE
  	if (engine)
  		{
  		if (!ENGINE_init(engine))
  			{
  			DSAerr(DSA_F_DSA_NEW_METHOD, ERR_R_ENGINE_LIB);
  			OPENSSL_free(ret);
  			return NULL;
  			}
  		ret->engine = engine;
  		}
  	else
  		ret->engine = ENGINE_get_default_DSA();
  	if(ret->engine)
  		{
  		ret->meth = ENGINE_get_DSA(ret->engine);
  		if(!ret->meth)
  			{
  			DSAerr(DSA_F_DSA_NEW_METHOD,
  				ERR_R_ENGINE_LIB);
  			ENGINE_finish(ret->engine);
  			OPENSSL_free(ret);
  			return NULL;
  			}
  		}
  #endif
  
  	ret->pad=0;
  	ret->version=0;
  	ret->write_params=1;
  	ret->p=NULL;
  	ret->q=NULL;
  	ret->g=NULL;
  
  	ret->pub_key=NULL;
  	ret->priv_key=NULL;
  
  	ret->kinv=NULL;
  	ret->r=NULL;
  	ret->method_mont_p=NULL;
  
  	ret->references=1;
  	ret->flags=ret->meth->flags & ~DSA_FLAG_NON_FIPS_ALLOW;
  	CRYPTO_new_ex_data(CRYPTO_EX_INDEX_DSA, ret, &ret->ex_data);
  	if ((ret->meth->init != NULL) && !ret->meth->init(ret))
  		{
  #ifndef OPENSSL_NO_ENGINE
  		if (ret->engine)
  			ENGINE_finish(ret->engine);
  #endif
  		CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DSA, ret, &ret->ex_data);
  		OPENSSL_free(ret);
  		ret=NULL;
  		}
  	
  	return(ret);
  	}
  
  void DSA_free(DSA *r)
  	{
  	int i;
  
  	if (r == NULL) return;
  
  	i=CRYPTO_add(&r->references,-1,CRYPTO_LOCK_DSA);
  #ifdef REF_PRINT
  	REF_PRINT("DSA",r);
  #endif
  	if (i > 0) return;
  #ifdef REF_CHECK
  	if (i < 0)
  		{
  		fprintf(stderr,"DSA_free, bad reference count\n");
  		abort();
  		}
  #endif
  
  	if(r->meth->finish)
  		r->meth->finish(r);
  #ifndef OPENSSL_NO_ENGINE
  	if(r->engine)
  		ENGINE_finish(r->engine);
  #endif
  
  	CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DSA, r, &r->ex_data);
  
  	if (r->p != NULL) BN_clear_free(r->p);
  	if (r->q != NULL) BN_clear_free(r->q);
  	if (r->g != NULL) BN_clear_free(r->g);
  	if (r->pub_key != NULL) BN_clear_free(r->pub_key);
  	if (r->priv_key != NULL) BN_clear_free(r->priv_key);
  	if (r->kinv != NULL) BN_clear_free(r->kinv);
  	if (r->r != NULL) BN_clear_free(r->r);
  	OPENSSL_free(r);
  	}
  
  int DSA_up_ref(DSA *r)
  	{
  	int i = CRYPTO_add(&r->references, 1, CRYPTO_LOCK_DSA);
  #ifdef REF_PRINT
  	REF_PRINT("DSA",r);
  #endif
  #ifdef REF_CHECK
  	if (i < 2)
  		{
  		fprintf(stderr, "DSA_up_ref, bad reference count\n");
  		abort();
  		}
  #endif
  	return ((i > 1) ? 1 : 0);
  	}
  
  int DSA_size(const DSA *r)
  	{
  	int ret,i;
  	ASN1_INTEGER bs;
  	unsigned char buf[4];	/* 4 bytes looks really small.
  				   However, i2d_ASN1_INTEGER() will not look
  				   beyond the first byte, as long as the second
  				   parameter is NULL. */
  
  	i=BN_num_bits(r->q);
  	bs.length=(i+7)/8;
  	bs.data=buf;
  	bs.type=V_ASN1_INTEGER;
  	/* If the top bit is set the asn1 encoding is 1 larger. */
  	buf[0]=0xff;	
  
  	i=i2d_ASN1_INTEGER(&bs,NULL);
  	i+=i; /* r and s */
  	ret=ASN1_object_size(1,i,V_ASN1_SEQUENCE);
  	return(ret);
  	}
  
  int DSA_get_ex_new_index(long argl, void *argp, CRYPTO_EX_new *new_func,
  	     CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func)
          {
  	return CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_DSA, argl, argp,
  				new_func, dup_func, free_func);
          }
  
  int DSA_set_ex_data(DSA *d, int idx, void *arg)
  	{
  	return(CRYPTO_set_ex_data(&d->ex_data,idx,arg));
  	}
  
  void *DSA_get_ex_data(DSA *d, int idx)
  	{
  	return(CRYPTO_get_ex_data(&d->ex_data,idx));
  	}
  
  int DSA_security_bits(const DSA *d)
  	{
  	return BN_security_bits(BN_num_bits(d->p), BN_num_bits(d->q));
  	}
  
  #ifndef OPENSSL_NO_DH
  DH *DSA_dup_DH(const DSA *r)
  	{
  	/* DSA has p, q, g, optional pub_key, optional priv_key.
  	 * DH has p, optional length, g, optional pub_key, optional priv_key,
  	 * optional q.
  	 */ 
  
  	DH *ret = NULL;
  
  	if (r == NULL)
  		goto err;
  	ret = DH_new();
  	if (ret == NULL)
  		goto err;
  	if (r->p != NULL) 
  		if ((ret->p = BN_dup(r->p)) == NULL)
  			goto err;
  	if (r->q != NULL)
  		{
  		ret->length = BN_num_bits(r->q);
  		if ((ret->q = BN_dup(r->q)) == NULL)
  			goto err;
  		}
  	if (r->g != NULL)
  		if ((ret->g = BN_dup(r->g)) == NULL)
  			goto err;
  	if (r->pub_key != NULL)
  		if ((ret->pub_key = BN_dup(r->pub_key)) == NULL)
  			goto err;
  	if (r->priv_key != NULL)
  		if ((ret->priv_key = BN_dup(r->priv_key)) == NULL)
  			goto err;
  
  	return ret;
  
   err:
  	if (ret != NULL)
  		DH_free(ret);
  	return NULL;
  	}
  #endif
  