/* crypto/bn/bn_mpi.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.]

 */

#include <stdio.h>

#include "cryptlib.h"

#include "bn_lcl.h"

EXPORT_C 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);

	}

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

	{

	long len;

	int neg=0;

	if (n < 4)

		{

		BNerr(BN_F_BN_MPI2BN,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)

		{

		BNerr(BN_F_BN_MPI2BN,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);

	}