1/* crypto/bn/bn_mpi.c */
2/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 * All rights reserved.
4 *
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
8 *
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to.  The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 *
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
26 * 1. Redistributions of source code must retain the copyright
27 *    notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 *    notice, this list of conditions and the following disclaimer in the
30 *    documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 *    must display the following acknowledgement:
33 *    "This product includes cryptographic software written by
34 *     Eric Young (eay@cryptsoft.com)"
35 *    The word 'cryptographic' can be left out if the rouines from the library
36 *    being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 *    the apps directory (application code) you must include an acknowledgement:
39 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 *
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51 * SUCH DAMAGE.
52 *
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed.  i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
57 */
58
59#include <stdio.h>
60#include "cryptlib.h"
61#include "bn_lcl.h"
62
63int BN_bn2mpi(const BIGNUM *a, unsigned char *d)
64	{
65	int bits;
66	int num=0;
67	int ext=0;
68	long l;
69
70	bits=BN_num_bits(a);
71	num=(bits+7)/8;
72	if (bits > 0)
73		{
74		ext=((bits & 0x07) == 0);
75		}
76	if (d == NULL)
77		return(num+4+ext);
78
79	l=num+ext;
80	d[0]=(unsigned char)(l>>24)&0xff;
81	d[1]=(unsigned char)(l>>16)&0xff;
82	d[2]=(unsigned char)(l>> 8)&0xff;
83	d[3]=(unsigned char)(l    )&0xff;
84	if (ext) d[4]=0;
85	num=BN_bn2bin(a,&(d[4+ext]));
86	if (a->neg)
87		d[4]|=0x80;
88	return(num+4+ext);
89	}
90
91BIGNUM *BN_mpi2bn(const unsigned char *d, int n, BIGNUM *a)
92	{
93	long len;
94	int neg=0;
95
96	if (n < 4)
97		{
98		BNerr(BN_F_BN_MPI2BN,BN_R_INVALID_LENGTH);
99		return(NULL);
100		}
101	len=((long)d[0]<<24)|((long)d[1]<<16)|((int)d[2]<<8)|(int)d[3];
102	if ((len+4) != n)
103		{
104		BNerr(BN_F_BN_MPI2BN,BN_R_ENCODING_ERROR);
105		return(NULL);
106		}
107
108	if (a == NULL) a=BN_new();
109	if (a == NULL) return(NULL);
110
111	if (len == 0)
112		{
113		a->neg=0;
114		a->top=0;
115		return(a);
116		}
117	d+=4;
118	if ((*d) & 0x80)
119		neg=1;
120	if (BN_bin2bn(d,(int)len,a) == NULL)
121		return(NULL);
122	a->neg=neg;
123	if (neg)
124		{
125		BN_clear_bit(a,BN_num_bits(a)-1);
126		}
127	bn_check_top(a);
128	return(a);
129	}
130
131