LCOV - code coverage report
Current view: top level - g10 - cipher.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 63 70 90.0 %
Date: 2015-11-05 17:10:59 Functions: 2 2 100.0 %

          Line data    Source code
       1             : /* cipher.c - En-/De-ciphering filter
       2             :  * Copyright (C) 1998, 1999, 2000, 2001, 2003,
       3             :  *               2006, 2009 Free Software Foundation, Inc.
       4             :  *
       5             :  * This file is part of GnuPG.
       6             :  *
       7             :  * GnuPG is free software; you can redistribute it and/or modify
       8             :  * it under the terms of the GNU General Public License as published by
       9             :  * the Free Software Foundation; either version 3 of the License, or
      10             :  * (at your option) any later version.
      11             :  *
      12             :  * GnuPG is distributed in the hope that it will be useful,
      13             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      14             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      15             :  * GNU General Public License for more details.
      16             :  *
      17             :  * You should have received a copy of the GNU General Public License
      18             :  * along with this program; if not, see <http://www.gnu.org/licenses/>.
      19             :  */
      20             : 
      21             : #include <config.h>
      22             : #include <stdio.h>
      23             : #include <stdlib.h>
      24             : #include <string.h>
      25             : #include <errno.h>
      26             : #include <assert.h>
      27             : 
      28             : #include "gpg.h"
      29             : #include "status.h"
      30             : #include "iobuf.h"
      31             : #include "util.h"
      32             : #include "filter.h"
      33             : #include "packet.h"
      34             : #include "options.h"
      35             : #include "main.h"
      36             : #include "status.h"
      37             : 
      38             : 
      39             : #define MIN_PARTIAL_SIZE 512
      40             : 
      41             : 
      42             : static void
      43         454 : write_header( cipher_filter_context_t *cfx, IOBUF a )
      44             : {
      45             :     gcry_error_t err;
      46             :     PACKET pkt;
      47             :     PKT_encrypted ed;
      48             :     byte temp[18];
      49             :     unsigned int blocksize;
      50             :     unsigned int nprefix;
      51             : 
      52         454 :     blocksize = openpgp_cipher_get_algo_blklen (cfx->dek->algo);
      53         454 :     if ( blocksize < 8 || blocksize > 16 )
      54           0 :         log_fatal("unsupported blocksize %u\n", blocksize );
      55             : 
      56         454 :     memset( &ed, 0, sizeof ed );
      57         454 :     ed.len = cfx->datalen;
      58         454 :     ed.extralen = blocksize+2;
      59         454 :     ed.new_ctb = !ed.len;
      60         454 :     if( cfx->dek->use_mdc ) {
      61         402 :         ed.mdc_method = DIGEST_ALGO_SHA1;
      62         402 :         gcry_md_open (&cfx->mdc_hash, DIGEST_ALGO_SHA1, 0);
      63         402 :         if ( DBG_HASHING )
      64           0 :             gcry_md_debug (cfx->mdc_hash, "creatmdc");
      65             :     }
      66             : 
      67             :     {
      68             :         char buf[20];
      69             : 
      70         454 :         sprintf (buf, "%d %d", ed.mdc_method, cfx->dek->algo);
      71         454 :         write_status_text (STATUS_BEGIN_ENCRYPTION, buf);
      72             :     }
      73             : 
      74         454 :     init_packet( &pkt );
      75         454 :     pkt.pkttype = cfx->dek->use_mdc? PKT_ENCRYPTED_MDC : PKT_ENCRYPTED;
      76         454 :     pkt.pkt.encrypted = &ed;
      77         454 :     if( build_packet( a, &pkt ))
      78           0 :         log_bug("build_packet(ENCR_DATA) failed\n");
      79         454 :     nprefix = blocksize;
      80         454 :     gcry_randomize (temp, nprefix, GCRY_STRONG_RANDOM );
      81         454 :     temp[nprefix] = temp[nprefix-2];
      82         454 :     temp[nprefix+1] = temp[nprefix-1];
      83         454 :     print_cipher_algo_note( cfx->dek->algo );
      84         454 :     err = openpgp_cipher_open (&cfx->cipher_hd,
      85             :                                cfx->dek->algo,
      86             :                                GCRY_CIPHER_MODE_CFB,
      87             :                                (GCRY_CIPHER_SECURE
      88             :                                 | ((cfx->dek->use_mdc || cfx->dek->algo >= 100)?
      89             :                                    0 : GCRY_CIPHER_ENABLE_SYNC)));
      90         454 :     if (err) {
      91             :         /* We should never get an error here cause we already checked,
      92             :          * that the algorithm is available.  */
      93           0 :         BUG();
      94             :     }
      95             : 
      96             : 
      97             : /*   log_hexdump( "thekey", cfx->dek->key, cfx->dek->keylen );*/
      98         454 :     gcry_cipher_setkey( cfx->cipher_hd, cfx->dek->key, cfx->dek->keylen );
      99         454 :     gcry_cipher_setiv( cfx->cipher_hd, NULL, 0 );
     100             : /*  log_hexdump( "prefix", temp, nprefix+2 ); */
     101         454 :     if (cfx->mdc_hash) /* Hash the "IV". */
     102         402 :         gcry_md_write (cfx->mdc_hash, temp, nprefix+2 );
     103         454 :     gcry_cipher_encrypt (cfx->cipher_hd, temp, nprefix+2, NULL, 0);
     104         454 :     gcry_cipher_sync (cfx->cipher_hd);
     105         454 :     iobuf_write(a, temp, nprefix+2);
     106         454 :     cfx->header=1;
     107         454 : }
     108             : 
     109             : 
     110             : 
     111             : /****************
     112             :  * This filter is used to en/de-cipher data with a conventional algorithm
     113             :  */
     114             : int
     115        2378 : cipher_filter( void *opaque, int control,
     116             :                IOBUF a, byte *buf, size_t *ret_len)
     117             : {
     118        2378 :     size_t size = *ret_len;
     119        2378 :     cipher_filter_context_t *cfx = opaque;
     120        2378 :     int rc=0;
     121             : 
     122        2378 :     if( control == IOBUFCTRL_UNDERFLOW ) { /* decrypt */
     123           0 :         rc = -1; /* not yet used */
     124             :     }
     125        2378 :     else if( control == IOBUFCTRL_FLUSH ) { /* encrypt */
     126        1470 :         assert(a);
     127        1470 :         if( !cfx->header ) {
     128         454 :             write_header( cfx, a );
     129             :         }
     130        1470 :         if (cfx->mdc_hash)
     131        1261 :             gcry_md_write (cfx->mdc_hash, buf, size);
     132        1470 :         gcry_cipher_encrypt (cfx->cipher_hd, buf, size, NULL, 0);
     133        1470 :         rc = iobuf_write( a, buf, size );
     134             :     }
     135         908 :     else if( control == IOBUFCTRL_FREE ) {
     136         454 :         if( cfx->mdc_hash ) {
     137             :             byte *hash;
     138         402 :             int hashlen = gcry_md_get_algo_dlen (gcry_md_get_algo
     139             :                                                  (cfx->mdc_hash));
     140             :             byte temp[22];
     141             : 
     142         402 :             assert( hashlen == 20 );
     143             :             /* We must hash the prefix of the MDC packet here. */
     144         402 :             temp[0] = 0xd3;
     145         402 :             temp[1] = 0x14;
     146         402 :             gcry_md_putc (cfx->mdc_hash, temp[0]);
     147         402 :             gcry_md_putc (cfx->mdc_hash, temp[1]);
     148             : 
     149         402 :             gcry_md_final (cfx->mdc_hash);
     150         402 :             hash = gcry_md_read (cfx->mdc_hash, 0);
     151         402 :             memcpy(temp+2, hash, 20);
     152         402 :             gcry_cipher_encrypt (cfx->cipher_hd, temp, 22, NULL, 0);
     153         402 :             gcry_md_close (cfx->mdc_hash); cfx->mdc_hash = NULL;
     154         402 :             if( iobuf_write( a, temp, 22 ) )
     155           0 :                 log_error("writing MDC packet failed\n" );
     156             :         }
     157         454 :         gcry_cipher_close (cfx->cipher_hd);
     158             :     }
     159         454 :     else if( control == IOBUFCTRL_DESC ) {
     160           0 :         *(char**)buf = "cipher_filter";
     161             :     }
     162        2378 :     return rc;
     163             : }

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