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gnupg/g10/cipher.c
Werner Koch c0c2c58054 Finished the bulk of changes for gnupg 1.9. This included switching
to libgcrypt functions, using shared error codes from libgpg-error,
replacing the old functions we used to have in ../util by those in
../jnlib and ../common, renaming the malloc functions and a couple of
types.  Note, that not all changes are listed below becuause they are
too similar and done at far too many places.  As of today the code
builds using the current libgcrypt from CVS but it is very unlikely
that it actually works.
2003-06-18 19:56:13 +00:00

166 lines
4.9 KiB
C

/* cipher.c - En-/De-ciphering filter
* Copyright (C) 1998, 1999, 2000, 2001, 2003 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include "gpg.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_t a )
{
PACKET pkt;
PKT_encrypted ed;
byte temp[18];
unsigned int blocksize;
unsigned int nprefix;
gpg_error_t rc;
blocksize = gcry_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, GCRY_MD_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 );
rc = gcry_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 (rc) {
/* 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_t 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;
rc = iobuf_write( a, temp, 22 );
if (rc)
log_error("writing MDC packet failed\n" );
}
gcry_cipher_close (cfx->cipher_hd);
}
else if( control == IOBUFCTRL_DESC ) {
*(char**)buf = "cipher_filter";
}
return rc;
}