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
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
|
/* cipher.c - En-/De-ciphering filter
* Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GnuPG 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 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include "errors.h"
#include "iobuf.h"
#include "memory.h"
#include "util.h"
#include "filter.h"
#include "packet.h"
#include "options.h"
#include "main.h"
#include "status.h"
#define MIN_PARTIAL_SIZE 512
static void
write_header( cipher_filter_context_t *cfx, IOBUF a )
{
PACKET pkt;
PKT_encrypted ed;
byte temp[18];
unsigned blocksize;
unsigned nprefix;
blocksize = cipher_get_blocksize( cfx->dek->algo );
if( blocksize < 8 || blocksize > 16 )
log_fatal("unsupported blocksize %u\n", blocksize );
memset( &ed, 0, sizeof ed );
ed.len = cfx->datalen;
ed.extralen = blocksize+2;
ed.new_ctb = !ed.len && !RFC1991;
if( cfx->dek->use_mdc ) {
ed.mdc_method = DIGEST_ALGO_SHA1;
cfx->mdc_hash = md_open( DIGEST_ALGO_SHA1, 0 );
if ( DBG_HASHING )
md_start_debug( cfx->mdc_hash, "creatmdc" );
}
{
char buf[20];
sprintf (buf, "%d %d", ed.mdc_method, cfx->dek->algo);
write_status_text (STATUS_BEGIN_ENCRYPTION, buf);
}
init_packet( &pkt );
pkt.pkttype = cfx->dek->use_mdc? PKT_ENCRYPTED_MDC : PKT_ENCRYPTED;
pkt.pkt.encrypted = &ed;
if( build_packet( a, &pkt ))
log_bug("build_packet(ENCR_DATA) failed\n");
nprefix = blocksize;
randomize_buffer( temp, nprefix, 1 );
temp[nprefix] = temp[nprefix-2];
temp[nprefix+1] = temp[nprefix-1];
print_cipher_algo_note( cfx->dek->algo );
cfx->cipher_hd = cipher_open( cfx->dek->algo,
cfx->dek->use_mdc? CIPHER_MODE_CFB
: CIPHER_MODE_AUTO_CFB, 1 );
/* log_hexdump( "thekey", cfx->dek->key, cfx->dek->keylen );*/
cipher_setkey( cfx->cipher_hd, cfx->dek->key, cfx->dek->keylen );
cipher_setiv( cfx->cipher_hd, NULL, 0 );
/* log_hexdump( "prefix", temp, nprefix+2 ); */
if( cfx->mdc_hash ) /* hash the "IV" */
md_write( cfx->mdc_hash, temp, nprefix+2 );
cipher_encrypt( cfx->cipher_hd, temp, temp, nprefix+2);
cipher_sync( cfx->cipher_hd );
iobuf_write(a, temp, nprefix+2);
cfx->header=1;
}
/****************
* This filter is used to en/de-cipher data with a conventional algorithm
*/
int
cipher_filter( void *opaque, int control,
IOBUF a, byte *buf, size_t *ret_len)
{
size_t size = *ret_len;
cipher_filter_context_t *cfx = opaque;
int rc=0;
if( control == IOBUFCTRL_UNDERFLOW ) { /* decrypt */
rc = -1; /* not yet used */
}
else if( control == IOBUFCTRL_FLUSH ) { /* encrypt */
assert(a);
if( !cfx->header ) {
write_header( cfx, a );
}
if( cfx->mdc_hash )
md_write( cfx->mdc_hash, buf, size );
cipher_encrypt( cfx->cipher_hd, buf, buf, size);
if( iobuf_write( a, buf, size ) )
rc = G10ERR_WRITE_FILE;
}
else if( control == IOBUFCTRL_FREE ) {
if( cfx->mdc_hash ) {
byte *hash;
int hashlen = md_digest_length( md_get_algo( cfx->mdc_hash ) );
byte temp[22];
assert( hashlen == 20 );
/* we must hash the prefix of the MDC packet here */
temp[0] = 0xd3;
temp[1] = 0x14;
md_putc( cfx->mdc_hash, temp[0] );
md_putc( cfx->mdc_hash, temp[1] );
md_final( cfx->mdc_hash );
hash = md_read( cfx->mdc_hash, 0 );
memcpy(temp+2, hash, 20);
cipher_encrypt( cfx->cipher_hd, temp, temp, 22 );
md_close( cfx->mdc_hash ); cfx->mdc_hash = NULL;
if( iobuf_write( a, temp, 22 ) )
log_error("writing MDC packet failed\n" );
}
cipher_close(cfx->cipher_hd);
}
else if( control == IOBUFCTRL_DESC ) {
*(char**)buf = "cipher_filter";
}
return rc;
}
|