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gnupg/g10/seckey-cert.c

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/* seckey-cert.c - secret key certificate packet handling
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* Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
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*
* This file is part of GnuPG.
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*
* GnuPG is free software; you can redistribute it and/or modify
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* 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,
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* 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"
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#include "main.h"
#include "options.h"
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#include "i18n.h"
#include "status.h"
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static int
do_check( PKT_secret_key *sk, const char *tryagain_text )
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{
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byte *buffer;
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u16 csum=0;
int i, res;
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unsigned nbytes;
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if( sk->is_protected ) { /* remove the protection */
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DEK *dek = NULL;
u32 keyid[4]; /* 4! because we need two of them */
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CIPHER_HANDLE cipher_hd=NULL;
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PKT_secret_key *save_sk;
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if( sk->protect.s2k.mode == 1001 ) {
log_info(_("secret key parts are not available\n"));
return G10ERR_GENERAL;
}
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if( sk->protect.algo == CIPHER_ALGO_NONE )
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BUG();
if( check_cipher_algo( sk->protect.algo ) ) {
log_info(_("protection algorithm %d%s is not supported\n"),
sk->protect.algo,sk->protect.algo==1?" (IDEA)":"" );
idea_cipher_warn(0);
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return G10ERR_CIPHER_ALGO;
}
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keyid_from_sk( sk, keyid );
keyid[2] = keyid[3] = 0;
if( !sk->is_primary ) {
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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, tryagain_text );
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cipher_hd = cipher_open( sk->protect.algo,
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CIPHER_MODE_AUTO_CFB, 1);
cipher_setkey( cipher_hd, dek->key, dek->keylen );
m_free(dek);
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save_sk = copy_secret_key( NULL, sk );
cipher_setiv( cipher_hd, sk->protect.iv, sk->protect.ivlen );
csum = 0;
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if( sk->version >= 4 ) {
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int ndata;
byte *p, *data;
u16 csumc = 0;
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i = pubkey_get_npkey(sk->pubkey_algo);
assert( mpi_is_opaque( sk->skey[i] ) );
p = mpi_get_opaque( sk->skey[i], &ndata );
if ( ndata > 1 )
csumc = p[ndata-2] << 8 | p[ndata-1];
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data = m_alloc_secure( ndata );
cipher_decrypt( cipher_hd, data, p, ndata );
mpi_free( sk->skey[i] ); sk->skey[i] = NULL ;
p = data;
if (sk->protect.sha1chk) {
/* This is the new SHA1 checksum method to detect
tampering with the key as used by the Klima/Rosa
attack */
sk->csum = 0;
csum = 1;
if( ndata < 20 )
log_error("not enough bytes for SHA-1 checksum\n");
else {
MD_HANDLE h = md_open (DIGEST_ALGO_SHA1, 1);
if (!h)
BUG(); /* algo not available */
md_write (h, data, ndata - 20);
md_final (h);
if (!memcmp (md_read (h, DIGEST_ALGO_SHA1),
data + ndata - 20, 20) ) {
/* digest does match. We have to keep the old
style checksum in sk->csum, so that the
test used for unprotected keys does work.
This test gets used when we are adding new
keys. */
sk->csum = csum = checksum (data, ndata-20);
}
md_close (h);
}
}
else {
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;
sk->skey[i] = mpi_read_from_buffer(p, &nbytes, 1 );
ndata -= nbytes;
p += nbytes;
}
/* Note: at this point ndata should be 2 for a simple
checksum or 20 for the sha1 digest */
}
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m_free(data);
}
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else {
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 & EMUBUG_GPGCHKSUM ) {
csum = sk->csum;
}
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}
cipher_close( cipher_hd );
/* now let's see whether we have used the right passphrase */
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if( csum != sk->csum ) {
copy_secret_key( sk, save_sk );
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passphrase_clear_cache ( keyid, sk->pubkey_algo );
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free_secret_key( save_sk );
return G10ERR_BAD_PASS;
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}
/* the checksum may fail, so we also check the key itself */
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res = pubkey_check_secret_key( sk->pubkey_algo, sk->skey );
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if( res ) {
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copy_secret_key( sk, save_sk );
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passphrase_clear_cache ( keyid, sk->pubkey_algo );
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free_secret_key( save_sk );
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return G10ERR_BAD_PASS;
}
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free_secret_key( save_sk );
sk->is_protected = 0;
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}
else { /* not protected, assume it is okay if the checksum is okay */
csum = 0;
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for(i=pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
csum += checksum_mpi( sk->skey[i] );
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}
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if( csum != sk->csum )
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return G10ERR_CHECKSUM;
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}
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return 0;
}
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/****************
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* Check the secret key
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* Ask up to 3 (or n) times for a correct passphrase
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*/
int
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check_secret_key( PKT_secret_key *sk, int n )
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{
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int rc = G10ERR_BAD_PASS;
int i;
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if( n < 1 )
n = (opt.batch && !opt.use_agent)? 1 : 3; /* use the default value */
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for(i=0; i < n && rc == G10ERR_BAD_PASS; i++ ) {
const char *tryagain = NULL;
if (i) {
tryagain = _("Invalid passphrase; please try again");
log_info (_("%s ...\n"), tryagain);
}
rc = do_check( sk, tryagain );
if( rc == G10ERR_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 );
}
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if( have_static_passphrase() )
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break;
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}
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if( !rc )
write_status( STATUS_GOOD_PASSPHRASE );
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return rc;
}
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/****************
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* check whether the secret key is protected.
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* Returns: 0 not protected, -1 on error or the protection algorithm
*/
int
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is_secret_key_protected( PKT_secret_key *sk )
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{
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return sk->is_protected? sk->protect.algo : 0;
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}
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/****************
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* Protect the secret key with the passphrase from DEK
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*/
int
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protect_secret_key( PKT_secret_key *sk, DEK *dek )
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{
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int i,j, rc = 0;
byte *buffer;
unsigned nbytes;
u16 csum;
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if( !dek )
return 0;
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if( !sk->is_protected ) { /* okay, apply the protection */
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CIPHER_HANDLE cipher_hd=NULL;
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if( check_cipher_algo( sk->protect.algo ) )
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rc = G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */
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else {
print_cipher_algo_note( sk->protect.algo );
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cipher_hd = cipher_open( sk->protect.algo,
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CIPHER_MODE_AUTO_CFB, 1 );
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if( cipher_setkey( cipher_hd, dek->key, dek->keylen ) )
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log_info(_("WARNING: Weak key detected"
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" - please change passphrase again.\n"));
sk->protect.ivlen = cipher_get_blocksize( sk->protect.algo );
assert( sk->protect.ivlen <= DIM(sk->protect.iv) );
if( sk->protect.ivlen != 8 && sk->protect.ivlen != 16 )
BUG(); /* yes, we are very careful */
randomize_buffer(sk->protect.iv, sk->protect.ivlen, 1);
cipher_setiv( cipher_hd, sk->protect.iv, sk->protect.ivlen );
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if( sk->version >= 4 ) {
byte *bufarr[PUBKEY_MAX_NSKEY];
unsigned narr[PUBKEY_MAX_NSKEY];
unsigned nbits[PUBKEY_MAX_NSKEY];
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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( !mpi_is_opaque( sk->skey[i] ) );
bufarr[j] = mpi_get_buffer( sk->skey[i], &narr[j], NULL );
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nbits[j] = mpi_get_nbits( sk->skey[i] );
ndata += narr[j] + 2;
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}
for( ; j < PUBKEY_MAX_NSKEY; j++ )
bufarr[j] = NULL;
ndata += opt.simple_sk_checksum? 2 : 20; /* for checksum */
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data = m_alloc_secure( ndata );
p = data;
for(j=0; j < PUBKEY_MAX_NSKEY && bufarr[j]; j++ ) {
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p[0] = nbits[j] >> 8 ;
p[1] = nbits[j];
p += 2;
memcpy(p, bufarr[j], narr[j] );
p += narr[j];
m_free(bufarr[j]);
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}
if (opt.simple_sk_checksum) {
log_info (_("generating the deprecated 16-bit checksum"
" for secret key protection\n"));
csum = checksum( data, ndata-2);
sk->csum = csum;
*p++ = csum >> 8;
*p++ = csum;
sk->protect.sha1chk = 0;
}
else {
MD_HANDLE h = md_open (DIGEST_ALGO_SHA1, 1);
if (!h)
BUG(); /* algo not available */
md_write (h, data, ndata - 20);
md_final (h);
memcpy (p, md_read (h, DIGEST_ALGO_SHA1), 20);
p += 20;
md_close (h);
sk->csum = csum = 0;
sk->protect.sha1chk = 1;
}
assert( p == data+ndata );
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cipher_encrypt( cipher_hd, data, data, ndata );
for(i = pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
mpi_free( sk->skey[i] );
sk->skey[i] = NULL;
}
i = pubkey_get_npkey(sk->pubkey_algo);
sk->skey[i] = mpi_set_opaque(NULL, data, ndata );
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}
else {
/* NOTE: we always recalculate the checksum because there
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* are some test releases which calculated it wrong */
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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;
}
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sk->is_protected = 1;
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cipher_close( cipher_hd );
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}
}
return rc;
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}
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