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
63 int 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
91 BIGNUM *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 }