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/* seckey-cert.c - secret key certifucate packet handling
* Copyright (C) 1998 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 <assert.h>
#include "util.h"
#include "memory.h"
#include "packet.h"
#include "mpi.h"
#include "keydb.h"
#include "cipher.h"
#include "main.h"
#include "options.h"
#include "i18n.h"
static int
do_check( PKT_secret_key *sk )
{
byte *buffer;
u16 csum=0;
int i, res;
unsigned nbytes;
if( sk->is_protected ) { /* remove the protection */
DEK *dek = NULL;
u32 keyid[2];
CIPHER_HANDLE cipher_hd=NULL;
PKT_secret_key *save_sk;
char save_iv[8];
if( sk->protect.algo == CIPHER_ALGO_NONE )
BUG();
if( check_cipher_algo( sk->protect.algo ) )
return G10ERR_CIPHER_ALGO; /* unsupported protection algorithm */
keyid_from_sk( sk, keyid );
dek = passphrase_to_dek( keyid, sk->protect.algo,
&sk->protect.s2k, 0 );
cipher_hd = cipher_open( sk->protect.algo,
CIPHER_MODE_AUTO_CFB, 1);
cipher_setkey( cipher_hd, dek->key, dek->keylen );
cipher_setiv( cipher_hd, NULL );
m_free(dek);
save_sk = copy_secret_key( NULL, sk );
memcpy(save_iv, sk->protect.iv, 8 );
cipher_decrypt( cipher_hd, sk->protect.iv, sk->protect.iv, 8 );
csum = 0;
for(i=pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
buffer = mpi_get_secure_buffer( sk->skey[i], &nbytes, NULL );
cipher_sync( cipher_hd );
assert( mpi_is_protected(sk->skey[i]) );
cipher_decrypt( cipher_hd, buffer, buffer, nbytes );
mpi_set_buffer( sk->skey[i], buffer, nbytes, 0 );
mpi_clear_protect_flag( sk->skey[i] );
csum += checksum_mpi( sk->skey[i] );
m_free( buffer );
}
if( opt.emulate_bugs & 1 ) {
csum = sk->csum;
}
cipher_close( cipher_hd );
/* now let's see whether we have used the right passphrase */
if( csum != sk->csum ) {
copy_secret_key( sk, save_sk );
free_secret_key( save_sk );
memcpy( sk->protect.iv, save_iv, 8 );
return G10ERR_BAD_PASS;
}
/* the checksum may fail, so we also check the key itself */
res = pubkey_check_secret_key( sk->pubkey_algo, sk->skey );
if( res ) {
copy_secret_key( sk, save_sk );
free_secret_key( save_sk );
memcpy( sk->protect.iv, save_iv, 8 );
return G10ERR_BAD_PASS;
}
free_secret_key( save_sk );
sk->is_protected = 0;
}
else { /* not protected, assume it is okay if the checksum is okay */
csum = 0;
for(i=pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
csum += checksum_mpi( sk->skey[i] );
}
if( csum != sk->csum )
return G10ERR_CHECKSUM;
}
return 0;
}
/****************
* Check the secret key
* Ask up to 3 times for a correct passphrase
*/
int
check_secret_key( PKT_secret_key *sk )
{
int rc = G10ERR_BAD_PASS;
int i;
for(i=0; i < 3 && rc == G10ERR_BAD_PASS; i++ ) {
if( i )
log_error(_("Invalid passphrase; please try again ...\n"));
rc = do_check( sk );
#if 0 /* set to 1 to enable the workaround */
if( rc == G10ERR_BAD_PASS && sk->is_protected
&& sk->protect.algo == CIPHER_ALGO_BLOWFISH
&& sk->pubkey_algo != PUBKEY_ALGO_ELGAMAL ) {
/* Workaround for a bug in 0.2.16 which still used
* a 160 bit key for BLOWFISH. */
log_info("trying workaround for 0.2.16 passphrase bug ...\n");
log_info("If you don't need this, uncomment it in g10/seckey-cert.c\n\n");
sk->protect.algo = CIPHER_ALGO_BLOWFISH160;
rc = do_check( sk );
if( rc )
rc = G10ERR_BAD_PASS;
sk->protect.algo = CIPHER_ALGO_BLOWFISH;
}
#endif
if( get_passphrase_fd() != -1 )
break;
}
return rc;
}
/****************
* check whether the secret key is protected.
* Returns: 0 not protected, -1 on error or the protection algorithm
*/
int
is_secret_key_protected( PKT_secret_key *sk )
{
return sk->is_protected? sk->protect.algo : 0;
}
/****************
* Protect the secret key with the passphrase from DEK
*/
int
protect_secret_key( PKT_secret_key *sk, DEK *dek )
{
int i, rc = 0;
byte *buffer;
unsigned nbytes;
u16 csum;
if( !dek )
return 0;
if( !sk->is_protected ) { /* okay, apply the protection */
CIPHER_HANDLE cipher_hd=NULL;
if( check_cipher_algo( sk->protect.algo ) )
rc = G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */
else {
cipher_hd = cipher_open( sk->protect.algo,
CIPHER_MODE_AUTO_CFB, 1 );
cipher_setkey( cipher_hd, dek->key, dek->keylen );
cipher_setiv( cipher_hd, NULL );
cipher_encrypt( cipher_hd, sk->protect.iv, sk->protect.iv, 8 );
/* NOTE: we always recalculate the checksum because there are some
* test releases which calculated it wrong */
csum = 0;
for(i=pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
csum += checksum_mpi_counted_nbits( sk->skey[i] );
buffer = mpi_get_buffer( sk->skey[i], &nbytes, NULL );
cipher_sync( cipher_hd );
assert( !mpi_is_protected(sk->skey[i]) );
cipher_encrypt( cipher_hd, buffer, buffer, nbytes );
mpi_set_buffer( sk->skey[i], buffer, nbytes, 0 );
mpi_set_protect_flag( sk->skey[i] );
m_free( buffer );
}
sk->csum = csum;
sk->is_protected = 1;
cipher_close( cipher_hd );
}
}
return rc;
}
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