1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
|
/*
* AFsplitter - Anti forensic information splitter
* Copyright 2004, Clemens Fruhwirth <clemens@endorphin.org>
*
* AFsplitter diffuses information over a large stripe of data,
* therefor supporting secure data destruction.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Library General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <errno.h>
#include "sha1.h"
#include "XORblock.h"
/* diffuse: Information spreading over the whole dataset with
* the help of sha512.
*/
static void diffuse(unsigned char *src, unsigned char *dst, size_t size)
{
sha1_ctx ctx;
uint32_t i;
uint32_t IV; /* host byte order independend hash IV */
unsigned int fullblocks = size / SHA1_DIGEST_SIZE;
unsigned int padding = size % SHA1_DIGEST_SIZE;
unsigned char final[SHA1_DIGEST_SIZE];
/* hash block the whole data set with different IVs to produce
* more than just a single data block
*/
for (i=0; i < fullblocks; i++) {
sha1_begin(&ctx);
IV = htonl(i);
sha1_hash((const unsigned char *) &IV, sizeof(IV), &ctx);
sha1_hash(src + SHA1_DIGEST_SIZE * i, SHA1_DIGEST_SIZE, &ctx);
sha1_end(dst + SHA1_DIGEST_SIZE * i, &ctx);
}
if(padding) {
sha1_begin(&ctx);
IV = htonl(i);
sha1_hash((const unsigned char *) &IV, sizeof(IV), &ctx);
sha1_hash(src + SHA1_DIGEST_SIZE * i, padding, &ctx);
sha1_end(final, &ctx);
memcpy(dst + SHA1_DIGEST_SIZE * i, final, padding);
}
}
/*
* Information splitting. The amount of data is multiplied by
* blocknumbers. The same blocksize and blocknumbers values
* must be supplied to AF_merge to recover information.
*/
int AF_split(char *src, char *dst, size_t blocksize, unsigned int blocknumbers)
{
unsigned int i;
char *bufblock;
int r = -EINVAL;
if((bufblock = calloc(blocksize, 1)) == NULL) return -ENOMEM;
/* process everything except the last block */
for(i=0; i<blocknumbers-1; i++) {
r = getRandom(dst+(blocksize*i),blocksize);
if(r < 0) goto out;
XORblock(dst+(blocksize*i),bufblock,bufblock,blocksize);
diffuse(bufblock,bufblock,blocksize);
}
/* the last block is computed */
XORblock(src,bufblock,dst+(i*blocksize),blocksize);
r = 0;
out:
free(bufblock);
return r;
}
int AF_merge(char *src, char *dst, size_t blocksize, unsigned int blocknumbers)
{
unsigned int i;
char *bufblock;
if((bufblock = calloc(blocksize, 1)) == NULL) return -ENOMEM;
memset(bufblock,0,blocksize);
for(i=0; i<blocknumbers-1; i++) {
XORblock(src+(blocksize*i),bufblock,bufblock,blocksize);
diffuse(bufblock,bufblock,blocksize);
}
XORblock(src + blocksize * i, bufblock, dst, blocksize);
free(bufblock);
return 0;
}
|
