mirror of git://git.gnupg.org/gnupg.git
407 lines
13 KiB
C
407 lines
13 KiB
C
/* seckey-cert.c - secret key certificate packet handling
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* Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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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
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* 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
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include "util.h"
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#include "memory.h"
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#include "packet.h"
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#include "mpi.h"
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#include "keydb.h"
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#include "cipher.h"
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#include "main.h"
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#include "options.h"
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#include "i18n.h"
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#include "status.h"
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static int
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do_check( PKT_secret_key *sk, const char *tryagain_text, int mode,
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int *canceled )
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{
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byte *buffer;
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u16 csum=0;
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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;
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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 ) {
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log_info(_("secret key parts are not available\n"));
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return G10ERR_GENERAL;
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}
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if( sk->protect.algo == CIPHER_ALGO_NONE )
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BUG();
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if( check_cipher_algo( sk->protect.algo ) ) {
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log_info(_("protection algorithm %d%s is not supported\n"),
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sk->protect.algo,sk->protect.algo==1?" (IDEA)":"" );
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if (sk->protect.algo==CIPHER_ALGO_IDEA)
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{
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write_status (STATUS_RSA_OR_IDEA);
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idea_cipher_warn (0);
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}
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return G10ERR_CIPHER_ALGO;
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}
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keyid_from_sk( sk, keyid );
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keyid[2] = keyid[3] = 0;
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if( !sk->is_primary ) {
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keyid[2] = sk->main_keyid[0];
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keyid[3] = sk->main_keyid[1];
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}
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dek = passphrase_to_dek( keyid, sk->pubkey_algo, sk->protect.algo,
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&sk->protect.s2k, mode,
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tryagain_text, canceled );
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if (!dek && canceled && *canceled)
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return G10ERR_GENERAL;
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cipher_hd = cipher_open( sk->protect.algo,
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CIPHER_MODE_AUTO_CFB, 1);
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cipher_setkey( cipher_hd, dek->key, dek->keylen );
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m_free(dek);
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save_sk = copy_secret_key( NULL, sk );
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cipher_setiv( cipher_hd, sk->protect.iv, sk->protect.ivlen );
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csum = 0;
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if( sk->version >= 4 ) {
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int ndata;
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byte *p, *data;
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u16 csumc = 0;
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i = pubkey_get_npkey(sk->pubkey_algo);
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assert( mpi_is_opaque( sk->skey[i] ) );
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p = mpi_get_opaque( sk->skey[i], &ndata );
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if ( ndata > 1 )
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csumc = p[ndata-2] << 8 | p[ndata-1];
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data = m_alloc_secure( ndata );
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cipher_decrypt( cipher_hd, data, p, ndata );
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mpi_free( sk->skey[i] ); sk->skey[i] = NULL ;
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p = data;
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if (sk->protect.sha1chk) {
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/* This is the new SHA1 checksum method to detect
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tampering with the key as used by the Klima/Rosa
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attack */
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sk->csum = 0;
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csum = 1;
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if( ndata < 20 )
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log_error("not enough bytes for SHA-1 checksum\n");
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else {
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MD_HANDLE h = md_open (DIGEST_ALGO_SHA1, 1);
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if (!h)
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BUG(); /* algo not available */
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md_write (h, data, ndata - 20);
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md_final (h);
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if (!memcmp (md_read (h, DIGEST_ALGO_SHA1),
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data + ndata - 20, 20) ) {
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/* digest does match. We have to keep the old
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style checksum in sk->csum, so that the
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test used for unprotected keys does work.
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This test gets used when we are adding new
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keys. */
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sk->csum = csum = checksum (data, ndata-20);
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}
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md_close (h);
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}
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}
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else {
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if( ndata < 2 ) {
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log_error("not enough bytes for checksum\n");
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sk->csum = 0;
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csum = 1;
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}
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else {
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csum = checksum( data, ndata-2);
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sk->csum = data[ndata-2] << 8 | data[ndata-1];
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if ( sk->csum != csum ) {
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/* This is a PGP 7.0.0 workaround */
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sk->csum = csumc; /* take the encrypted one */
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}
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}
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}
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/* must check it here otherwise the mpi_read_xx would fail
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because the length may have an arbitrary value */
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if( sk->csum == csum ) {
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for( ; i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
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nbytes = ndata;
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sk->skey[i] = mpi_read_from_buffer(p, &nbytes, 1 );
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ndata -= nbytes;
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p += nbytes;
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}
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/* Note: at this point ndata should be 2 for a simple
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checksum or 20 for the sha1 digest */
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}
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m_free(data);
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}
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else {
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for(i=pubkey_get_npkey(sk->pubkey_algo);
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i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
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byte *p;
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int ndata;
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unsigned int dummy;
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assert (mpi_is_opaque (sk->skey[i]));
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p = mpi_get_opaque (sk->skey[i], &ndata);
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assert (ndata >= 2);
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assert (ndata == ((p[0] << 8 | p[1]) + 7)/8 + 2);
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buffer = m_alloc_secure (ndata);
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cipher_sync (cipher_hd);
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buffer[0] = p[0];
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buffer[1] = p[1];
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cipher_decrypt (cipher_hd, buffer+2, p+2, ndata-2);
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csum += checksum (buffer, ndata);
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mpi_free (sk->skey[i]);
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dummy = ndata;
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sk->skey[i] = mpi_read_from_buffer (buffer, &dummy, 1);
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assert (sk->skey[i]);
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m_free (buffer);
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/* csum += checksum_mpi (sk->skey[i]); */
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}
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}
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cipher_close( cipher_hd );
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/* now let's see whether we have used the right passphrase */
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if( csum != sk->csum ) {
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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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}
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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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}
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free_secret_key( save_sk );
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sk->is_protected = 0;
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}
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else { /* not protected, assume it is okay if the checksum is okay */
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csum = 0;
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for(i=pubkey_get_npkey(sk->pubkey_algo);
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i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
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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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/****************
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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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* If n is negative, disable the key info prompt and make n=abs(n)
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*/
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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;
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int i,mode;
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if (sk && sk->is_protected && sk->protect.s2k.mode == 1002)
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return 0; /* Let the card support stuff handle this. */
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if(n<0)
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{
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n=abs(n);
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mode=1;
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}
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else
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mode=0;
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if( n < 1 )
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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++ ) {
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int canceled = 0;
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const char *tryagain = NULL;
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if (i) {
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tryagain = N_("Invalid passphrase; please try again");
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log_info (_("%s ...\n"), _(tryagain));
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}
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rc = do_check( sk, tryagain, mode, &canceled );
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if( rc == G10ERR_BAD_PASS && is_status_enabled() ) {
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u32 kid[2];
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char buf[50];
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keyid_from_sk( sk, kid );
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sprintf(buf, "%08lX%08lX", (ulong)kid[0], (ulong)kid[1]);
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write_status_text( STATUS_BAD_PASSPHRASE, buf );
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}
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if( have_static_passphrase() || canceled)
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break;
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}
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if( !rc )
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write_status( STATUS_GOOD_PASSPHRASE );
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return rc;
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}
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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
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* -2 indicates a card stub.
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*/
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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?
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sk->protect.s2k.mode == 1002? -2
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: 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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*/
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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;
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byte *buffer;
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unsigned nbytes;
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u16 csum;
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if( !dek )
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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 {
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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"));
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sk->protect.ivlen = cipher_get_blocksize( sk->protect.algo );
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assert( sk->protect.ivlen <= DIM(sk->protect.iv) );
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if( sk->protect.ivlen != 8 && sk->protect.ivlen != 16 )
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BUG(); /* yes, we are very careful */
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randomize_buffer(sk->protect.iv, sk->protect.ivlen, 1);
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cipher_setiv( cipher_hd, sk->protect.iv, sk->protect.ivlen );
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if( sk->version >= 4 ) {
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byte *bufarr[PUBKEY_MAX_NSKEY];
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unsigned narr[PUBKEY_MAX_NSKEY];
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unsigned nbits[PUBKEY_MAX_NSKEY];
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int ndata=0;
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byte *p, *data;
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for(j=0, i = pubkey_get_npkey(sk->pubkey_algo);
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i < pubkey_get_nskey(sk->pubkey_algo); i++, j++ ) {
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assert( !mpi_is_opaque( sk->skey[i] ) );
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bufarr[j] = mpi_get_buffer( sk->skey[i], &narr[j], NULL );
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nbits[j] = mpi_get_nbits( sk->skey[i] );
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ndata += narr[j] + 2;
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}
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for( ; j < PUBKEY_MAX_NSKEY; j++ )
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bufarr[j] = NULL;
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ndata += opt.simple_sk_checksum? 2 : 20; /* for checksum */
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data = m_alloc_secure( ndata );
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p = data;
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for(j=0; j < PUBKEY_MAX_NSKEY && bufarr[j]; j++ ) {
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p[0] = nbits[j] >> 8 ;
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p[1] = nbits[j];
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p += 2;
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memcpy(p, bufarr[j], narr[j] );
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p += narr[j];
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m_free(bufarr[j]);
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}
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if (opt.simple_sk_checksum) {
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log_info (_("generating the deprecated 16-bit checksum"
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" for secret key protection\n"));
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csum = checksum( data, ndata-2);
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sk->csum = csum;
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*p++ = csum >> 8;
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*p++ = csum;
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sk->protect.sha1chk = 0;
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}
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else {
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MD_HANDLE h = md_open (DIGEST_ALGO_SHA1, 1);
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if (!h)
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BUG(); /* algo not available */
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md_write (h, data, ndata - 20);
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md_final (h);
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memcpy (p, md_read (h, DIGEST_ALGO_SHA1), 20);
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p += 20;
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md_close (h);
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sk->csum = csum = 0;
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sk->protect.sha1chk = 1;
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}
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assert( p == data+ndata );
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cipher_encrypt( cipher_hd, data, data, ndata );
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for(i = pubkey_get_npkey(sk->pubkey_algo);
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i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
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mpi_free( sk->skey[i] );
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sk->skey[i] = NULL;
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}
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i = pubkey_get_npkey(sk->pubkey_algo);
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sk->skey[i] = mpi_set_opaque(NULL, data, ndata );
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}
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else {
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csum = 0;
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for(i=pubkey_get_npkey(sk->pubkey_algo);
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i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
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byte *data;
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unsigned int nbits;
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csum += checksum_mpi (sk->skey[i]);
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buffer = mpi_get_buffer( sk->skey[i], &nbytes, NULL );
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cipher_sync (cipher_hd);
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assert ( !mpi_is_opaque (sk->skey[i]) );
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data = m_alloc (nbytes+2);
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nbits = mpi_get_nbits (sk->skey[i]);
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assert (nbytes == (nbits + 7)/8);
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data[0] = nbits >> 8;
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data[1] = nbits;
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cipher_encrypt (cipher_hd, data+2, buffer, nbytes);
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m_free( buffer );
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mpi_free (sk->skey[i]);
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sk->skey[i] = mpi_set_opaque (NULL, data, nbytes+2);
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}
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sk->csum = csum;
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}
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sk->is_protected = 1;
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cipher_close( cipher_hd );
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}
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}
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return rc;
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}
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