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gnupg/g10/seckey-cert.c
Werner Koch b1eac93431 Support the not anymore patented IDEA cipher algorithm.
* cipher/idea.c: New.  Take from Libgcrypt master and adjust for
direct use in GnuPG.
* cipher/idea-stub.c: Remove.
* cipher/Makefile.am: Add idea.c and remove idea-stub.c rules.
* configure.ac: Remove idea-stub code.
* g10/gpg.c (check_permissions): Remove code path for ITEM==2.
(main): Make --load-extension a dummy option.
* g10/keygen.c (keygen_set_std_prefs): Include IDEA only in PGP2
compatibility mode.
* g10/misc.c (idea_cipher_warn): Remove.  Also remove all callers.
* g10/seckey-cert.c (do_check): Remove emitting of STATUS_RSA_OR_IDEA.
* g10/status.c (get_status_string): Remove STATUS_RSA_OR_IDEA.
* g10/status.h (STATUS_RSA_OR_IDEA): Remove.

--

To keep the number of actually used algorithms low, we support IDEA
only in a basically read-only way (unless --pgp2 is used during key
generation).  It does not make sense to suggest the use of this old 64
bit blocksize algorithm.  However, there is old data available where
it might be helpful to have IDEA available.
2012-11-08 13:25:02 +01:00

421 lines
13 KiB
C

/* seckey-cert.c - secret key certificate packet handling
* Copyright (C) 1998, 1999, 2000, 2001, 2002 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 <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"
#include "status.h"
static int
do_check( PKT_secret_key *sk, const char *tryagain_text, int mode,
int *canceled )
{
byte *buffer;
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 */
CIPHER_HANDLE cipher_hd=NULL;
PKT_secret_key *save_sk;
if( sk->protect.s2k.mode == 1001 ) {
log_info(_("secret key parts are not available\n"));
return G10ERR_GENERAL;
}
if( sk->protect.algo == CIPHER_ALGO_NONE )
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)":"" );
return G10ERR_CIPHER_ALGO;
}
if(check_digest_algo(sk->protect.s2k.hash_algo))
{
log_info(_("protection digest %d is not supported\n"),
sk->protect.s2k.hash_algo);
return G10ERR_DIGEST_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, mode,
tryagain_text, canceled );
if (!dek && canceled && *canceled)
return G10ERR_GENERAL;
cipher_hd = cipher_open( sk->protect.algo,
CIPHER_MODE_AUTO_CFB, 1);
cipher_setkey( cipher_hd, dek->key, dek->keylen );
xfree(dek);
save_sk = copy_secret_key( NULL, sk );
cipher_setiv( cipher_hd, sk->protect.iv, sk->protect.ivlen );
csum = 0;
if( sk->version >= 4 ) {
unsigned int ndata;
byte *p, *data;
u16 csumc = 0;
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];
data = xmalloc_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 );
if (!sk->skey[i])
{
/* Checksum was okay, but not correctly
decrypted. */
sk->csum = 0;
csum = 1;
break;
}
ndata -= nbytes;
p += nbytes;
}
/* Note: at this point ndata should be 2 for a simple
checksum or 20 for the sha1 digest */
}
xfree(data);
}
else {
for(i=pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
byte *p;
unsigned int ndata;
assert (mpi_is_opaque (sk->skey[i]));
p = mpi_get_opaque (sk->skey[i], &ndata);
assert (ndata >= 2);
assert (ndata == ((p[0] << 8 | p[1]) + 7)/8 + 2);
buffer = xmalloc_secure (ndata);
cipher_sync (cipher_hd);
buffer[0] = p[0];
buffer[1] = p[1];
cipher_decrypt (cipher_hd, buffer+2, p+2, ndata-2);
csum += checksum (buffer, ndata);
mpi_free (sk->skey[i]);
sk->skey[i] = mpi_read_from_buffer (buffer, &ndata, 1);
xfree (buffer);
if (!sk->skey[i])
{
/* Checksum was okay, but not correctly
decrypted. */
sk->csum = 0;
csum = 1;
break;
}
/* csum += checksum_mpi (sk->skey[i]); */
}
}
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, NULL, sk->pubkey_algo );
free_secret_key( save_sk );
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 );
passphrase_clear_cache ( keyid, NULL, sk->pubkey_algo );
free_secret_key( save_sk );
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 (or n) times for a correct passphrase
* If n is negative, disable the key info prompt and make n=abs(n)
*/
int
check_secret_key( PKT_secret_key *sk, int n )
{
int rc = G10ERR_BAD_PASS;
int i,mode;
if (sk && sk->is_protected && sk->protect.s2k.mode == 1002)
return 0; /* Let the card support stuff handle this. */
if(n<0)
{
n=abs(n);
mode=1;
}
else
mode=0;
if( n < 1 )
n = (opt.batch && !opt.use_agent)? 1 : 3; /* use the default value */
for(i=0; i < n && rc == G10ERR_BAD_PASS; i++ ) {
int canceled = 0;
const char *tryagain = NULL;
if (i) {
tryagain = N_("Invalid passphrase; please try again");
log_info (_("%s ...\n"), _(tryagain));
}
rc = do_check( sk, tryagain, mode, &canceled );
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 );
}
if( have_static_passphrase() || canceled)
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
* -2 indicates a card stub.
* -3 indicates a not-online stub.
*/
int
is_secret_key_protected( PKT_secret_key *sk )
{
return sk->is_protected?
sk->protect.s2k.mode == 1002? -2 :
sk->protect.s2k.mode == 1001? -3 : 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 */
CIPHER_HANDLE cipher_hd=NULL;
if( check_cipher_algo( sk->protect.algo ) )
rc = G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */
else {
print_cipher_algo_note( sk->protect.algo );
cipher_hd = cipher_open( sk->protect.algo,
CIPHER_MODE_AUTO_CFB, 1 );
if( cipher_setkey( cipher_hd, dek->key, dek->keylen ) )
log_info(_("WARNING: Weak key detected"
" - 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 );
if( sk->version >= 4 ) {
byte *bufarr[PUBKEY_MAX_NSKEY];
unsigned narr[PUBKEY_MAX_NSKEY];
unsigned nbits[PUBKEY_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( !mpi_is_opaque( sk->skey[i] ) );
bufarr[j] = mpi_get_buffer( sk->skey[i], &narr[j], NULL );
nbits[j] = mpi_get_nbits( sk->skey[i] );
ndata += narr[j] + 2;
}
for( ; j < PUBKEY_MAX_NSKEY; j++ )
bufarr[j] = NULL;
ndata += opt.simple_sk_checksum? 2 : 20; /* for checksum */
data = xmalloc_secure( ndata );
p = data;
for(j=0; j < PUBKEY_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];
xfree(bufarr[j]);
}
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 );
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 );
}
else {
csum = 0;
for(i=pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
byte *data;
unsigned int nbits;
csum += checksum_mpi (sk->skey[i]);
buffer = mpi_get_buffer( sk->skey[i], &nbytes, NULL );
cipher_sync (cipher_hd);
assert ( !mpi_is_opaque (sk->skey[i]) );
data = xmalloc (nbytes+2);
nbits = mpi_get_nbits (sk->skey[i]);
assert (nbytes == (nbits + 7)/8);
data[0] = nbits >> 8;
data[1] = nbits;
cipher_encrypt (cipher_hd, data+2, buffer, nbytes);
xfree( buffer );
mpi_free (sk->skey[i]);
sk->skey[i] = mpi_set_opaque (NULL, data, nbytes+2);
}
sk->csum = csum;
}
sk->is_protected = 1;
cipher_close( cipher_hd );
}
}
return rc;
}