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 "internal/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
  
  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 = OPENSSL_zalloc(sizeof(*ret));
      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->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);
  
      BN_clear_free(r->p);
      BN_clear_free(r->q);
      BN_clear_free(r->g);
      BN_clear_free(r->pub_key);
      BN_clear_free(r->priv_key);
      BN_clear_free(r->kinv);
      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:
      DH_free(ret);
      return NULL;
  }
  #endif
  