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211 lines
5.9 KiB
C
211 lines
5.9 KiB
C
/* seckey-cert.c - secret key certifucate packet handling
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* Copyright (C) 1998 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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static int
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do_check( PKT_secret_key *sk )
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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[2];
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CIPHER_HANDLE cipher_hd=NULL;
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PKT_secret_key *save_sk;
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char save_iv[8];
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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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return G10ERR_CIPHER_ALGO; /* unsupported protection algorithm */
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keyid_from_sk( sk, keyid );
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dek = passphrase_to_dek( keyid, sk->protect.algo,
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&sk->protect.s2k, 0 );
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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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cipher_setiv( cipher_hd, NULL );
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m_free(dek);
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save_sk = copy_secret_key( NULL, sk );
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memcpy(save_iv, sk->protect.iv, 8 );
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cipher_decrypt( cipher_hd, sk->protect.iv, sk->protect.iv, 8 );
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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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buffer = mpi_get_secure_buffer( sk->skey[i], &nbytes, NULL );
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cipher_sync( cipher_hd );
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assert( mpi_is_protected(sk->skey[i]) );
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cipher_decrypt( cipher_hd, buffer, buffer, nbytes );
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mpi_set_buffer( sk->skey[i], buffer, nbytes, 0 );
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mpi_clear_protect_flag( sk->skey[i] );
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csum += checksum_mpi( sk->skey[i] );
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m_free( buffer );
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}
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if( opt.emulate_bugs & 1 ) {
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csum = sk->csum;
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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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free_secret_key( save_sk );
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memcpy( sk->protect.iv, save_iv, 8 );
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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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free_secret_key( save_sk );
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memcpy( sk->protect.iv, save_iv, 8 );
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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 times for a correct passphrase
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*/
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int
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check_secret_key( PKT_secret_key *sk )
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{
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int rc = G10ERR_BAD_PASS;
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int i;
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for(i=0; i < 3 && rc == G10ERR_BAD_PASS; i++ ) {
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if( i )
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log_error(_("Invalid passphrase; please try again ...\n"));
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rc = do_check( sk );
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#if 0 /* set to 1 to enable the workaround */
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if( rc == G10ERR_BAD_PASS && sk->is_protected
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&& sk->protect.algo == CIPHER_ALGO_BLOWFISH
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&& sk->pubkey_algo != PUBKEY_ALGO_ELGAMAL ) {
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/* Workaround for a bug in 0.2.16 which still used
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* a 160 bit key for BLOWFISH. */
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log_info("trying workaround for 0.2.16 passphrase bug ...\n");
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log_info("If you don't need this, uncomment it in g10/seckey-cert.c\n\n");
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sk->protect.algo = CIPHER_ALGO_BLOWFISH160;
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rc = do_check( sk );
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if( rc )
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rc = G10ERR_BAD_PASS;
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sk->protect.algo = CIPHER_ALGO_BLOWFISH;
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}
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#endif
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if( get_passphrase_fd() != -1 )
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break;
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}
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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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*/
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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? 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, 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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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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cipher_setiv( cipher_hd, NULL );
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cipher_encrypt( cipher_hd, sk->protect.iv, sk->protect.iv, 8 );
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/* NOTE: we always recalculate the checksum because there are some
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* test releases which calculated it wrong */
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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_counted_nbits( 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_protected(sk->skey[i]) );
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cipher_encrypt( cipher_hd, buffer, buffer, nbytes );
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mpi_set_buffer( sk->skey[i], buffer, nbytes, 0 );
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mpi_set_protect_flag( sk->skey[i] );
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m_free( buffer );
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}
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sk->csum = csum;
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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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