1
0
mirror of git://git.gnupg.org/gnupg.git synced 2024-12-22 10:19:57 +01:00
gnupg/g10/cipher.c
Werner Koch b008274afd Nuked almost all trailing white space.
We better do this once and for all instead of cluttering all future
commits with diffs of trailing white spaces.  In the majority of cases
blank or single lines are affected and thus this change won't disturb
a git blame too much.  For future commits the pre-commit scripts
checks that this won't happen again.
2011-02-04 12:57:53 +01:00

164 lines
4.7 KiB
C

/* cipher.c - En-/De-ciphering filter
* Copyright (C) 1998, 1999, 2000, 2001, 2003,
* 2006, 2009 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include "gpg.h"
#include "status.h"
#include "iobuf.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 )
{
gcry_error_t err;
PACKET pkt;
PKT_encrypted ed;
byte temp[18];
unsigned int blocksize;
unsigned int nprefix;
blocksize = openpgp_cipher_get_algo_blklen (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;
gcry_md_open (&cfx->mdc_hash, DIGEST_ALGO_SHA1, 0);
if ( DBG_HASHING )
gcry_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;
gcry_randomize (temp, nprefix, GCRY_STRONG_RANDOM );
temp[nprefix] = temp[nprefix-2];
temp[nprefix+1] = temp[nprefix-1];
print_cipher_algo_note( cfx->dek->algo );
err = openpgp_cipher_open (&cfx->cipher_hd,
cfx->dek->algo,
GCRY_CIPHER_MODE_CFB,
(GCRY_CIPHER_SECURE
| ((cfx->dek->use_mdc || cfx->dek->algo >= 100)?
0 : GCRY_CIPHER_ENABLE_SYNC)));
if (err) {
/* We should never get an error here cause we already checked,
* that the algorithm is available. */
BUG();
}
/* log_hexdump( "thekey", cfx->dek->key, cfx->dek->keylen );*/
gcry_cipher_setkey( cfx->cipher_hd, cfx->dek->key, cfx->dek->keylen );
gcry_cipher_setiv( cfx->cipher_hd, NULL, 0 );
/* log_hexdump( "prefix", temp, nprefix+2 ); */
if (cfx->mdc_hash) /* Hash the "IV". */
gcry_md_write (cfx->mdc_hash, temp, nprefix+2 );
gcry_cipher_encrypt (cfx->cipher_hd, temp, nprefix+2, NULL, 0);
gcry_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)
gcry_md_write (cfx->mdc_hash, buf, size);
gcry_cipher_encrypt (cfx->cipher_hd, buf, size, NULL, 0);
rc = iobuf_write( a, buf, size );
}
else if( control == IOBUFCTRL_FREE ) {
if( cfx->mdc_hash ) {
byte *hash;
int hashlen = gcry_md_get_algo_dlen (gcry_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;
gcry_md_putc (cfx->mdc_hash, temp[0]);
gcry_md_putc (cfx->mdc_hash, temp[1]);
gcry_md_final (cfx->mdc_hash);
hash = gcry_md_read (cfx->mdc_hash, 0);
memcpy(temp+2, hash, 20);
gcry_cipher_encrypt (cfx->cipher_hd, temp, 22, NULL, 0);
gcry_md_close (cfx->mdc_hash); cfx->mdc_hash = NULL;
if( iobuf_write( a, temp, 22 ) )
log_error("writing MDC packet failed\n" );
}
gcry_cipher_close (cfx->cipher_hd);
}
else if( control == IOBUFCTRL_DESC ) {
*(char**)buf = "cipher_filter";
}
return rc;
}