/* $OpenBSD: bn_mpi.c,v 1.8 2017/01/29 17:49:22 beck 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.]

 */

#include <stdio.h>

#include <openssl/err.h>

#include "bn_lcl.h"

int

BN_bn2mpi(const BIGNUM *a, unsigned char *d)

{

  int bits;

  int num = 0;

  int ext = 0;

  long l;

  bits = BN_num_bits(a);

  num = (bits + 7) / 8;

  if (bits > 0) {

    ext = ((bits & 0x07) == 0);

  }

  if (d == NULL)

    return (num + 4 + ext);

  l = num + ext;

  d[0] = (unsigned char)(l >> 24) & 0xff;

  d[1] = (unsigned char)(l >> 16) & 0xff;

  d[2] = (unsigned char)(l >> 8) & 0xff;

  d[3] = (unsigned char)(l) & 0xff;

  if (ext)

    d[4] = 0;

  num = BN_bn2bin(a, &(d[4 + ext]));

  if (a->neg)

    d[4] |= 0x80;

  return (num + 4 + ext);

}

BIGNUM *

BN_mpi2bn(const unsigned char *d, int n, BIGNUM *a)

{

  long len;

  int neg = 0;

  if (n < 4) {

    BNerror(BN_R_INVALID_LENGTH);

    return (NULL);

  }

  len = ((long)d[0] << 24) | ((long)d[1] << 16) | ((int)d[2] << 8) |

      (int)d[3];

  if ((len + 4) != n) {

    BNerror(BN_R_ENCODING_ERROR);

    return (NULL);

  }

  if (a == NULL)

    a = BN_new();

  if (a == NULL)

    return (NULL);

  if (len == 0) {

    a->neg = 0;

    a->top = 0;

    return (a);

  }

  d += 4;

  if ((*d) & 0x80)

    neg = 1;

  if (BN_bin2bn(d, (int)len, a) == NULL)

    return (NULL);

  a->neg = neg;

  if (neg) {

    BN_clear_bit(a, BN_num_bits(a) - 1);

  }

  bn_check_top(a);

  return (a);

}