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gnupg/g10/seckey-cert.c

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/* seckey-cert.c - secret key certificate packet handling
* Copyright (C) 1998, 1999, 2000 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 <gcrypt.h>
#include "util.h"
#include "packet.h"
#include "keydb.h"
#include "main.h"
#include "options.h"
#include "i18n.h"
#include "status.h"
/****************
* Emulate our old PK interface here - sometime in the future we might
* change the internal design to directly fit to libgcrypt.
*/
static int
pk_check_secret_key( int algo, MPI *skey )
{
GCRY_SEXP s_skey;
int rc;
/* make a sexp from skey */
if( algo == GCRY_PK_DSA ) {
rc = gcry_sexp_build ( &s_skey, NULL,
"(private-key(dsa(p%m)(q%m)(g%m)(y%m)(x%m)))",
skey[0], skey[1], skey[2], skey[3], skey[4] );
}
else if( algo == GCRY_PK_ELG || algo == GCRY_PK_ELG_E ) {
rc = gcry_sexp_build ( &s_skey, NULL,
"(private-key(elg(p%m)(g%m)(y%m)(x%m)))",
skey[0], skey[1], skey[2], skey[3] );
}
else if( algo == GCRY_PK_RSA ) {
rc = gcry_sexp_build ( &s_skey, NULL,
"(private-key(rsa(n%m)(e%m)(d%m)(p%m)(q%m)(u%m)))",
skey[0], skey[1], skey[2], skey[3], skey[4], skey[5] );
}
else
return GPGERR_PUBKEY_ALGO;
if ( rc )
BUG ();
rc = gcry_pk_testkey( s_skey );
gcry_sexp_release( s_skey );
return rc;
}
static int
do_check( PKT_secret_key *sk )
{
u16 csum=0;
int i, res;
unsigned nbytes;
if( sk->is_protected ) { /* remove the protection */
DEK *dek = NULL;
u32 keyid[4]; /* 4! because we need two of them */
GCRY_CIPHER_HD cipher_hd=NULL;
PKT_secret_key *save_sk;
if( sk->protect.s2k.mode == 1001 ) {
log_info(_("secret key parts are not available\n"));
return GPGERR_GENERAL;
}
if( sk->protect.algo == GCRY_CIPHER_NONE )
BUG();
if( openpgp_cipher_test_algo( sk->protect.algo ) ) {
log_info(_("protection algorithm %d is not supported\n"),
sk->protect.algo );
return GPGERR_CIPHER_ALGO;
}
keyid_from_sk( sk, keyid );
keyid[2] = keyid[3] = 0;
if( !sk->is_primary ) {
keyid[2] = sk->main_keyid[0];
keyid[3] = sk->main_keyid[1];
}
dek = passphrase_to_dek( keyid, sk->pubkey_algo, sk->protect.algo,
&sk->protect.s2k, 0 );
/* Hmmm: Do we use sync mode here even for Twofish? */
if( !(cipher_hd = gcry_cipher_open( sk->protect.algo,
GCRY_CIPHER_MODE_CFB,
GCRY_CIPHER_SECURE
| (sk->protect.algo >= 100 ?
0 : GCRY_CIPHER_ENABLE_SYNC) ) )
) {
BUG();
}
if( gcry_cipher_setkey( cipher_hd, dek->key, dek->keylen ) )
log_fatal("set key failed: %s\n", gcry_strerror(-1) );
gcry_free(dek);
save_sk = copy_secret_key( NULL, sk );
if( gcry_cipher_setiv( cipher_hd, sk->protect.iv, sk->protect.ivlen ))
log_fatal("set IV failed: %s\n", gcry_strerror(-1) );
csum = 0;
if( sk->version >= 4 ) {
size_t ndata;
unsigned int ndatabits;
byte *p, *data;
u16 csumc = 0;
i = pubkey_get_npkey(sk->pubkey_algo);
assert( gcry_mpi_get_flag( sk->skey[i], GCRYMPI_FLAG_OPAQUE ) );
p = gcry_mpi_get_opaque( sk->skey[i], &ndatabits );
ndata = (ndatabits+7)/8;
if ( ndata > 1 )
csumc = p[ndata-2] << 8 | p[ndata-1];
data = gcry_xmalloc_secure( ndata );
gcry_cipher_decrypt( cipher_hd, data, ndata, p, ndata );
mpi_release( sk->skey[i] ); sk->skey[i] = NULL ;
p = data;
if( ndata < 2 ) {
log_error("not enough bytes for checksum\n");
sk->csum = 0;
csum = 1;
}
else {
csum = checksum( data, ndata-2);
sk->csum = data[ndata-2] << 8 | data[ndata-1];
if ( sk->csum != csum ) {
/* This is a PGP 7.0.0 workaround */
sk->csum = csumc; /* take the encrypted one */
}
}
/* must check it here otherwise the mpi_read_xx would fail
* because the length may have an arbitrary value */
if( sk->csum == csum ) {
for( ; i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
nbytes = ndata;
assert( gcry_is_secure( p ) );
res = gcry_mpi_scan( &sk->skey[i], GCRYMPI_FMT_PGP,
p, &nbytes);
if( res )
log_bug("gcry_mpi_scan failed in do_check: rc=%d\n", res);
ndata -= nbytes;
p += nbytes;
}
}
gcry_free(data);
}
else {
for(i=pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
size_t ndata;
unsigned int ndatabits;
byte *p, *data;
assert( gcry_mpi_get_flag( sk->skey[i], GCRYMPI_FLAG_OPAQUE ) );
p = gcry_mpi_get_opaque( sk->skey[i], &ndatabits );
ndata = (ndatabits+7)/8;
data = gcry_xmalloc_secure( ndata );
gcry_cipher_sync( cipher_hd );
gcry_cipher_decrypt( cipher_hd, data, ndata, p, ndata );
mpi_release( sk->skey[i] ); sk->skey[i] = NULL ;
res = gcry_mpi_scan( &sk->skey[i], GCRYMPI_FMT_USG,
data, &ndata );
if( res )
log_bug("gcry_mpi_scan failed in do_check: rc=%d\n", res);
csum += checksum_mpi( sk->skey[i] );
gcry_free( data );
}
}
gcry_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 );
passphrase_clear_cache ( keyid, sk->pubkey_algo );
free_secret_key( save_sk );
return GPGERR_BAD_PASS;
}
/* the checksum may be correct in some cases,
* so we also check the key itself */
res = pk_check_secret_key( sk->pubkey_algo, sk->skey );
if( res ) {
copy_secret_key( sk, save_sk );
passphrase_clear_cache ( keyid, sk->pubkey_algo );
free_secret_key( save_sk );
return GPGERR_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++ ) {
assert( !gcry_mpi_get_flag( sk->skey[i], GCRYMPI_FLAG_OPAQUE ) );
csum += checksum_mpi( sk->skey[i] );
}
if( csum != sk->csum )
return GPGERR_CHECKSUM;
}
return 0;
}
/****************
* Check the secret key
* Ask up to 3 (or n) times for a correct passphrase
*/
int
check_secret_key( PKT_secret_key *sk, int n )
{
int rc = GPGERR_BAD_PASS;
int i;
if( n < 1 )
n = opt.batch? 1 : 3; /* use the default value */
for(i=0; i < n && rc == GPGERR_BAD_PASS; i++ ) {
if( i )
log_info(_("Invalid passphrase; please try again ...\n"));
rc = do_check( sk );
if( rc == GPGERR_BAD_PASS && is_status_enabled() ) {
u32 kid[2];
char buf[50];
keyid_from_sk( sk, kid );
sprintf(buf, "%08lX%08lX", (ulong)kid[0], (ulong)kid[1]);
write_status_text( STATUS_BAD_PASSPHRASE, buf );
}
if( have_static_passphrase() )
break;
}
if( !rc )
write_status( STATUS_GOOD_PASSPHRASE );
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,j, rc = 0;
byte *buffer;
unsigned nbytes;
u16 csum;
if( !dek )
return 0;
if( !sk->is_protected ) { /* okay, apply the protection */
GCRY_CIPHER_HD cipher_hd=NULL;
if( openpgp_cipher_test_algo( sk->protect.algo ) )
rc = GPGERR_CIPHER_ALGO; /* unsupport protection algorithm */
else {
print_cipher_algo_note( sk->protect.algo );
if( !(cipher_hd = gcry_cipher_open( sk->protect.algo,
GCRY_CIPHER_MODE_CFB,
GCRY_CIPHER_SECURE
| (sk->protect.algo >= 100 ?
0 : GCRY_CIPHER_ENABLE_SYNC) ))
) {
BUG();
}
rc = gcry_cipher_setkey( cipher_hd, dek->key, dek->keylen );
if( rc == GCRYERR_WEAK_KEY ) {
log_info(_("WARNING: Weak key detected"
" - please change passphrase again.\n"));
rc = 0;
}
else if( rc )
BUG();
/* set the IV length */
{ int blocksize = gcry_cipher_get_algo_blklen( sk->protect.algo );
if( blocksize != 8 && blocksize != 16 )
log_fatal("unsupported blocksize %d\n", blocksize );
sk->protect.ivlen = blocksize;
assert( sk->protect.ivlen <= DIM(sk->protect.iv) );
}
gcry_randomize(sk->protect.iv, sk->protect.ivlen,
GCRY_STRONG_RANDOM);
gcry_cipher_setiv( cipher_hd, sk->protect.iv, sk->protect.ivlen );
/* FIXME: replace set/get buffer */
if( sk->version >= 4 ) {
byte *bufarr[GNUPG_MAX_NSKEY];
unsigned narr[GNUPG_MAX_NSKEY];
unsigned nbits[GNUPG_MAX_NSKEY];
int ndata=0;
byte *p, *data;
for(j=0, i = pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++, j++ ) {
assert( !gcry_mpi_get_flag( sk->skey[i], GCRYMPI_FLAG_OPAQUE ) );
if( gcry_mpi_aprint( GCRYMPI_FMT_USG, (void**)bufarr+j,
narr+j, sk->skey[i]))
BUG();
nbits[j] = gcry_mpi_get_nbits( sk->skey[i] );
ndata += narr[j] + 2;
}
for( ; j < GNUPG_MAX_NSKEY; j++ )
bufarr[j] = NULL;
ndata += 2; /* for checksum */
data = gcry_xmalloc_secure( ndata );
p = data;
for(j=0; j < GNUPG_MAX_NSKEY && bufarr[j]; j++ ) {
p[0] = nbits[j] >> 8 ;
p[1] = nbits[j];
p += 2;
memcpy(p, bufarr[j], narr[j] );
p += narr[j];
gcry_free(bufarr[j]);
}
csum = checksum( data, ndata-2);
sk->csum = csum;
*p++ = csum >> 8;
*p++ = csum;
assert( p == data+ndata );
gcry_cipher_encrypt( cipher_hd, data, ndata, NULL, 0 );
for(i = pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
mpi_release( sk->skey[i] );
sk->skey[i] = NULL;
}
i = pubkey_get_npkey(sk->pubkey_algo);
sk->skey[i] = gcry_mpi_set_opaque(NULL, data, ndata*8 );
}
else {
/* NOTE: we always recalculate the checksum because there
* are some test releases which calculated it wrong */
/* FIXME: Replace this code -- Hmmm: why */
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( gcry_mpi_aprint( GCRYMPI_FMT_USG,
&buffer, &nbytes, sk->skey[i] ) )
BUG();
gcry_cipher_sync( cipher_hd );
assert( !gcry_mpi_get_flag( sk->skey[i], GCRYMPI_FLAG_OPAQUE ) );
gcry_cipher_encrypt( cipher_hd, buffer, nbytes, NULL, 0 );
gcry_mpi_release( sk->skey[i] );
if( gcry_mpi_scan( &sk->skey[i], GCRYMPI_FMT_USG,
buffer,&nbytes ) )
BUG();
gcry_free( buffer );
}
sk->csum = csum;
}
sk->is_protected = 1;
gcry_cipher_close( cipher_hd );
}
}
return rc;
}
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