/* $OpenBSD: dsa_lib.c,v 1.48 2024/03/27 01:49:31 tb Exp $ */

/* 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 <openssl/opensslconf.h>

#include <openssl/asn1.h>

#include <openssl/bn.h>

#include <openssl/dsa.h>

#include <openssl/err.h>

#ifndef OPENSSL_NO_DH

#include <openssl/dh.h>

#endif

#include "dh_local.h"

#include "dsa_local.h"

static const DSA_METHOD *default_DSA_method = NULL;

void

DSA_set_default_method(const DSA_METHOD *meth)

{

  default_DSA_method = meth;

}

LCRYPTO_ALIAS(DSA_set_default_method);

const DSA_METHOD *

DSA_get_default_method(void)

{

  if (!default_DSA_method)

    default_DSA_method = DSA_OpenSSL();

  return default_DSA_method;

}

LCRYPTO_ALIAS(DSA_get_default_method);

DSA *

DSA_new(void)

{

  return DSA_new_method(NULL);

}

LCRYPTO_ALIAS(DSA_new);

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);

  dsa->meth = meth;

  if (meth->init)

    meth->init(dsa);

  return 1;

}

LCRYPTO_ALIAS(DSA_set_method);

DSA *

DSA_new_method(ENGINE *engine)

{

  DSA *dsa;

  if ((dsa = calloc(1, sizeof(DSA))) == NULL) {

    DSAerror(ERR_R_MALLOC_FAILURE);

    goto err;

  }

  dsa->meth = DSA_get_default_method();

  dsa->flags = dsa->meth->flags & ~DSA_FLAG_NON_FIPS_ALLOW;

  dsa->references = 1;

  if (!CRYPTO_new_ex_data(CRYPTO_EX_INDEX_DSA, dsa, &dsa->ex_data))

    goto err;

  if (dsa->meth->init != NULL && !dsa->meth->init(dsa))

    goto err;

  return dsa;

 err:

  DSA_free(dsa);

  return NULL;

}

LCRYPTO_ALIAS(DSA_new_method);

void

DSA_free(DSA *dsa)

{

  if (dsa == NULL)

    return;

  if (CRYPTO_add(&dsa->references, -1, CRYPTO_LOCK_DSA) > 0)

    return;

  if (dsa->meth != NULL && dsa->meth->finish != NULL)

    dsa->meth->finish(dsa);

  CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DSA, dsa, &dsa->ex_data);

  BN_free(dsa->p);

  BN_free(dsa->q);

  BN_free(dsa->g);

  BN_free(dsa->pub_key);

  BN_free(dsa->priv_key);

  BN_free(dsa->kinv);

  BN_free(dsa->r);

  free(dsa);

}

LCRYPTO_ALIAS(DSA_free);

int

DSA_up_ref(DSA *dsa)

{

  return CRYPTO_add(&dsa->references, 1, CRYPTO_LOCK_DSA) > 1;

}

LCRYPTO_ALIAS(DSA_up_ref);

int

DSA_size(const DSA *dsa)

{

  DSA_SIG signature;

  int ret = 0;

  signature.r = dsa->q;

  signature.s = dsa->q;

  if ((ret = i2d_DSA_SIG(&signature, NULL)) < 0)

    ret = 0;

  return ret;

}

LCRYPTO_ALIAS(DSA_size);

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);

}

LCRYPTO_ALIAS(DSA_get_ex_new_index);

int

DSA_set_ex_data(DSA *dsa, int idx, void *arg)

{

  return CRYPTO_set_ex_data(&dsa->ex_data, idx, arg);

}

LCRYPTO_ALIAS(DSA_set_ex_data);

void *

DSA_get_ex_data(DSA *dsa, int idx)

{

  return CRYPTO_get_ex_data(&dsa->ex_data, idx);

}

LCRYPTO_ALIAS(DSA_get_ex_data);

int

DSA_security_bits(const DSA *dsa)

{

  if (dsa->p == NULL || dsa->q == NULL)

    return -1;

  return BN_security_bits(BN_num_bits(dsa->p), BN_num_bits(dsa->q));

}

LCRYPTO_ALIAS(DSA_security_bits);

#ifndef OPENSSL_NO_DH

DH *

DSA_dup_DH(const DSA *dsa)

{

  /*

   * 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 *dh = NULL;

  if (dsa == NULL)

    goto err;

  if ((dh = DH_new()) == NULL)

    goto err;

  if (dsa->p != NULL) {

    if ((dh->p = BN_dup(dsa->p)) == NULL)

      goto err;

  }

  if (dsa->q != NULL) {

    dh->length = BN_num_bits(dsa->q);

    if ((dh->q = BN_dup(dsa->q)) == NULL)

      goto err;

  }

  if (dsa->g != NULL) {

    if ((dh->g = BN_dup(dsa->g)) == NULL)

      goto err;

  }

  if (dsa->pub_key != NULL) {

    if ((dh->pub_key = BN_dup(dsa->pub_key)) == NULL)

      goto err;

  }

  if (dsa->priv_key != NULL) {

    if ((dh->priv_key = BN_dup(dsa->priv_key)) == NULL)

      goto err;

  }

  return dh;

 err:

  DH_free(dh);

  return NULL;

}

LCRYPTO_ALIAS(DSA_dup_DH);

#endif

void

DSA_get0_pqg(const DSA *dsa, const BIGNUM **p, const BIGNUM **q, const BIGNUM **g)

{

  if (p != NULL)

    *p = dsa->p;

  if (q != NULL)

    *q = dsa->q;

  if (g != NULL)

    *g = dsa->g;

}

LCRYPTO_ALIAS(DSA_get0_pqg);

int

DSA_set0_pqg(DSA *dsa, BIGNUM *p, BIGNUM *q, BIGNUM *g)

{

  if ((dsa->p == NULL && p == NULL) || (dsa->q == NULL && q == NULL) ||

      (dsa->g == NULL && g == NULL))

    return 0;

  if (p != NULL) {

    BN_free(dsa->p);

    dsa->p = p;

  }

  if (q != NULL) {

    BN_free(dsa->q);

    dsa->q = q;

  }

  if (g != NULL) {

    BN_free(dsa->g);

    dsa->g = g;

  }

  return 1;

}

LCRYPTO_ALIAS(DSA_set0_pqg);

void

DSA_get0_key(const DSA *dsa, const BIGNUM **pub_key, const BIGNUM **priv_key)

{

  if (pub_key != NULL)

    *pub_key = dsa->pub_key;

  if (priv_key != NULL)

    *priv_key = dsa->priv_key;

}

LCRYPTO_ALIAS(DSA_get0_key);

int

DSA_set0_key(DSA *dsa, BIGNUM *pub_key, BIGNUM *priv_key)

{

  if (dsa->pub_key == NULL && pub_key == NULL)

    return 0;

  if (pub_key != NULL) {

    BN_free(dsa->pub_key);

    dsa->pub_key = pub_key;

  }

  if (priv_key != NULL) {

    BN_free(dsa->priv_key);

    dsa->priv_key = priv_key;

  }

  return 1;

}

LCRYPTO_ALIAS(DSA_set0_key);

const BIGNUM *

DSA_get0_p(const DSA *dsa)

{

  return dsa->p;

}

LCRYPTO_ALIAS(DSA_get0_p);

const BIGNUM *

DSA_get0_q(const DSA *dsa)

{

  return dsa->q;

}

LCRYPTO_ALIAS(DSA_get0_q);

const BIGNUM *

DSA_get0_g(const DSA *dsa)

{

  return dsa->g;

}

LCRYPTO_ALIAS(DSA_get0_g);

const BIGNUM *

DSA_get0_pub_key(const DSA *dsa)

{

  return dsa->pub_key;

}

LCRYPTO_ALIAS(DSA_get0_pub_key);

const BIGNUM *

DSA_get0_priv_key(const DSA *dsa)

{

  return dsa->priv_key;

}

LCRYPTO_ALIAS(DSA_get0_priv_key);

void

DSA_clear_flags(DSA *dsa, int flags)

{

  dsa->flags &= ~flags;

}

LCRYPTO_ALIAS(DSA_clear_flags);

int

DSA_test_flags(const DSA *dsa, int flags)

{

  return dsa->flags & flags;

}

LCRYPTO_ALIAS(DSA_test_flags);

void

DSA_set_flags(DSA *dsa, int flags)

{

  dsa->flags |= flags;

}

LCRYPTO_ALIAS(DSA_set_flags);

ENGINE *

DSA_get0_engine(DSA *dsa)

{

  return NULL;

}

LCRYPTO_ALIAS(DSA_get0_engine);

int

DSA_bits(const DSA *dsa)

{

  return BN_num_bits(dsa->p);

}

LCRYPTO_ALIAS(DSA_bits);

int

dsa_check_key(const DSA *dsa)

{

  int p_bits, q_bits;

  if (dsa->p == NULL || dsa->q == NULL || dsa->g == NULL) {

    DSAerror(DSA_R_MISSING_PARAMETERS);

    return 0;

  }

  /* Checking that p and q are primes is expensive. Check they are odd. */

  if (!BN_is_odd(dsa->p) || !BN_is_odd(dsa->q)) {

    DSAerror(DSA_R_INVALID_PARAMETERS);

    return 0;

  }

  /* FIPS 186-4: 1 < g < p. */

  if (BN_cmp(dsa->g, BN_value_one()) <= 0 ||

      BN_cmp(dsa->g, dsa->p) >= 0) {

    DSAerror(DSA_R_INVALID_PARAMETERS);

    return 0;

  }

  /* We know p and g are positive. The next two checks imply q > 0. */

  if (BN_is_negative(dsa->q)) {

    DSAerror(DSA_R_BAD_Q_VALUE);

    return 0;

  }

  /* FIPS 186-4 only allows three sizes for q. */

  q_bits = BN_num_bits(dsa->q);

  if (q_bits != 160 && q_bits != 224 && q_bits != 256) {

    DSAerror(DSA_R_BAD_Q_VALUE);

    return 0;

  }

  /*

   * XXX - FIPS 186-4 only allows 1024, 2048, and 3072 bits for p.

   * Cap the size to reduce DoS risks. Poor defaults make keys with

   * incorrect p sizes >= 512 bits common, so only enforce a weak

   * lower bound.

   */

  p_bits = BN_num_bits(dsa->p);

  if (p_bits > OPENSSL_DSA_MAX_MODULUS_BITS) {

    DSAerror(DSA_R_MODULUS_TOO_LARGE);

    return 0;

  }

  if (p_bits < 512) {

    DSAerror(DSA_R_INVALID_PARAMETERS);

    return 0;

  }

  /* The public key must be in the multiplicative group (mod p). */

  if (dsa->pub_key != NULL) {

    if (BN_cmp(dsa->pub_key, BN_value_one()) <= 0 ||

        BN_cmp(dsa->pub_key, dsa->p) >= 0) {

      DSAerror(DSA_R_INVALID_PARAMETERS);

      return 0;

    }

  }

  /* The private key must be nonzero and in GF(q). */

  if (dsa->priv_key != NULL) {

    if (BN_cmp(dsa->priv_key, BN_value_one()) < 0 ||

        BN_cmp(dsa->priv_key, dsa->q) >= 0) {

      DSAerror(DSA_R_INVALID_PARAMETERS);

      return 0;

    }

  }

  return 1;

}