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gnupg/g10/encode.c
David Shaw 27949781ec PGP2 patch. --pgp2 sets things up for pgp2 compatibility, and prints a 
warning if the user does something that would make the message not
compatible (i.e. encrypt with a non-RSA key, etc.)
2001-12-07 15:24:32 +00:00

536 lines
15 KiB
C
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/* encode.c - encode data
* Copyright (C) 1998, 1999, 2000, 2001 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 2 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, 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 <errno.h>
#include <assert.h>
#include "options.h"
#include "packet.h"
#include "errors.h"
#include "iobuf.h"
#include "keydb.h"
#include "memory.h"
#include "util.h"
#include "main.h"
#include "filter.h"
#include "trustdb.h"
#include "i18n.h"
#include "status.h"
static int encode_simple( const char *filename, int mode );
static int write_pubkey_enc_from_list( PK_LIST pk_list, DEK *dek, IOBUF out );
/****************
* Encode FILENAME with only the symmetric cipher. Take input from
* stdin if FILENAME is NULL.
*/
int
encode_symmetric( const char *filename )
{
return encode_simple( filename, 1 );
}
/****************
* Encode FILENAME as a literal data packet only. Take input from
* stdin if FILENAME is NULL.
*/
int
encode_store( const char *filename )
{
return encode_simple( filename, 0 );
}
static int
encode_simple( const char *filename, int mode )
{
IOBUF inp, out;
PACKET pkt;
PKT_plaintext *pt = NULL;
STRING2KEY *s2k = NULL;
int rc = 0;
u32 filesize;
cipher_filter_context_t cfx;
armor_filter_context_t afx;
compress_filter_context_t zfx;
text_filter_context_t tfx;
int do_compress = opt.compress && !opt.rfc1991;
memset( &cfx, 0, sizeof cfx);
memset( &afx, 0, sizeof afx);
memset( &zfx, 0, sizeof zfx);
memset( &tfx, 0, sizeof tfx);
init_packet(&pkt);
/* prepare iobufs */
if( !(inp = iobuf_open(filename)) ) {
log_error(_("%s: can't open: %s\n"), filename? filename: "[stdin]",
strerror(errno) );
return G10ERR_OPEN_FILE;
}
if( opt.textmode )
iobuf_push_filter( inp, text_filter, &tfx );
cfx.dek = NULL;
if( mode ) {
s2k = m_alloc_clear( sizeof *s2k );
s2k->mode = opt.rfc1991? 0:opt.s2k_mode;
s2k->hash_algo = opt.def_digest_algo ? opt.def_digest_algo
: opt.s2k_digest_algo;
cfx.dek = passphrase_to_dek( NULL, 0,
opt.def_cipher_algo ? opt.def_cipher_algo
: opt.s2k_cipher_algo , s2k, 2 );
if( !cfx.dek || !cfx.dek->keylen ) {
rc = G10ERR_PASSPHRASE;
m_free(cfx.dek);
m_free(s2k);
iobuf_close(inp);
log_error(_("error creating passphrase: %s\n"), g10_errstr(rc) );
return rc;
}
}
if( (rc = open_outfile( filename, opt.armor? 1:0, &out )) ) {
iobuf_cancel(inp);
m_free(cfx.dek);
m_free(s2k);
return rc;
}
if( opt.armor )
iobuf_push_filter( out, armor_filter, &afx );
#ifdef ENABLE_COMMENT_PACKETS
else {
write_comment( out, "#created by GNUPG v" VERSION " ("
PRINTABLE_OS_NAME ")");
if( opt.comment_string )
write_comment( out, opt.comment_string );
}
#endif
if( s2k && !opt.rfc1991 ) {
PKT_symkey_enc *enc = m_alloc_clear( sizeof *enc );
enc->version = 4;
enc->cipher_algo = cfx.dek->algo;
enc->s2k = *s2k;
pkt.pkttype = PKT_SYMKEY_ENC;
pkt.pkt.symkey_enc = enc;
if( (rc = build_packet( out, &pkt )) )
log_error("build symkey packet failed: %s\n", g10_errstr(rc) );
m_free(enc);
}
if (!opt.no_literal) {
/* setup the inner packet */
if( filename || opt.set_filename ) {
char *s = make_basename( opt.set_filename ? opt.set_filename
: filename );
pt = m_alloc( sizeof *pt + strlen(s) - 1 );
pt->namelen = strlen(s);
memcpy(pt->name, s, pt->namelen );
m_free(s);
}
else { /* no filename */
pt = m_alloc( sizeof *pt - 1 );
pt->namelen = 0;
}
}
/* pgp5 has problems to decrypt symmetrically encrypted data from
* GnuPG if the filelength is in the inner packet. It works
* when only partial length headers are use. Until we have
* tracked this problem down. We use this temporary fix
* (fixme: remove the && !mode )
*/
if( filename && !opt.textmode && !mode ) {
if( !(filesize = iobuf_get_filelength(inp)) )
log_info(_("%s: WARNING: empty file\n"), filename );
/* we can't yet encode the length of very large files,
* so we switch to partial lengthn encoding in this case */
if ( filesize >= IOBUF_FILELENGTH_LIMIT )
filesize = 0;
}
else
filesize = opt.set_filesize ? opt.set_filesize : 0; /* stdin */
if (!opt.no_literal) {
pt->timestamp = make_timestamp();
pt->mode = opt.textmode? 't' : 'b';
pt->len = filesize;
pt->new_ctb = !pt->len && !opt.rfc1991;
pt->buf = inp;
pkt.pkttype = PKT_PLAINTEXT;
pkt.pkt.plaintext = pt;
cfx.datalen = filesize && !do_compress ? calc_packet_length( &pkt ) : 0;
}
else
cfx.datalen = filesize && !do_compress ? filesize : 0;
/* register the cipher filter */
if( mode )
iobuf_push_filter( out, cipher_filter, &cfx );
/* register the compress filter */
if( do_compress )
iobuf_push_filter( out, compress_filter, &zfx );
/* do the work */
if (!opt.no_literal) {
if( (rc = build_packet( out, &pkt )) )
log_error("build_packet failed: %s\n", g10_errstr(rc) );
}
else {
/* user requested not to create a literal packet,
* so we copy the plain data */
byte copy_buffer[4096];
int bytes_copied;
while ((bytes_copied = iobuf_read(inp, copy_buffer, 4096)) != -1)
if (iobuf_write(out, copy_buffer, bytes_copied) == -1) {
rc = G10ERR_WRITE_FILE;
log_error("copying input to output failed: %s\n", g10_errstr(rc) );
break;
}
memset(copy_buffer, 0, 4096); /* burn buffer */
}
/* finish the stuff */
iobuf_close(inp);
if (rc)
iobuf_cancel(out);
else {
iobuf_close(out); /* fixme: check returncode */
if (mode)
write_status( STATUS_END_ENCRYPTION );
}
if (pt)
pt->buf = NULL;
free_packet(&pkt);
m_free(cfx.dek);
m_free(s2k);
return rc;
}
/****************
* Encrypt the file with the given userids (or ask if none
* is supplied).
*/
int
encode_crypt( const char *filename, STRLIST remusr )
{
IOBUF inp = NULL, out = NULL;
PACKET pkt;
PKT_plaintext *pt = NULL;
int rc = 0;
u32 filesize;
cipher_filter_context_t cfx;
armor_filter_context_t afx;
compress_filter_context_t zfx;
text_filter_context_t tfx;
PK_LIST pk_list,work_list;
int do_compress = opt.compress && !opt.rfc1991;
memset( &cfx, 0, sizeof cfx);
memset( &afx, 0, sizeof afx);
memset( &zfx, 0, sizeof zfx);
memset( &tfx, 0, sizeof tfx);
init_packet(&pkt);
if( (rc=build_pk_list( remusr, &pk_list, PUBKEY_USAGE_ENC)) )
return rc;
if(opt.pgp2)
for(work_list=pk_list;work_list->next!=NULL;work_list=work_list->next)
if(!(is_RSA(work_list->pk->pubkey_algo) &&
nbits_from_pk(work_list->pk)<=2048))
{
log_info(_("You can only encrypt to RSA keys of 2048 bits or "
"less in --pgp2 mode\n"));
log_info(_("This message will not be usable by PGP 2.x\n"));
break;
}
/* prepare iobufs */
if( !(inp = iobuf_open(filename)) ) {
log_error(_("can't open %s: %s\n"), filename? filename: "[stdin]",
strerror(errno) );
rc = G10ERR_OPEN_FILE;
goto leave;
}
else if( opt.verbose )
log_info(_("reading from `%s'\n"), filename? filename: "[stdin]");
if( opt.textmode )
iobuf_push_filter( inp, text_filter, &tfx );
if( (rc = open_outfile( filename, opt.armor? 1:0, &out )) )
goto leave;
if( opt.armor )
iobuf_push_filter( out, armor_filter, &afx );
#ifdef ENABLE_COMMENT_PACKETS
else {
write_comment( out, "#created by GNUPG v" VERSION " ("
PRINTABLE_OS_NAME ")");
if( opt.comment_string )
write_comment( out, opt.comment_string );
}
#endif
/* create a session key */
cfx.dek = m_alloc_secure_clear (sizeof *cfx.dek);
if( !opt.def_cipher_algo ) { /* try to get it from the prefs */
cfx.dek->algo = select_algo_from_prefs( pk_list, PREFTYPE_SYM );
if( cfx.dek->algo == -1 )
cfx.dek->algo = DEFAULT_CIPHER_ALGO;
}
else
cfx.dek->algo = opt.def_cipher_algo;
cfx.dek->use_mdc = select_mdc_from_pklist (pk_list);
make_session_key( cfx.dek );
if( DBG_CIPHER )
log_hexdump("DEK is: ", cfx.dek->key, cfx.dek->keylen );
rc = write_pubkey_enc_from_list( pk_list, cfx.dek, out );
if( rc )
goto leave;
if (!opt.no_literal) {
/* setup the inner packet */
if( filename || opt.set_filename ) {
char *s = make_basename( opt.set_filename ? opt.set_filename : filename );
pt = m_alloc( sizeof *pt + strlen(s) - 1 );
pt->namelen = strlen(s);
memcpy(pt->name, s, pt->namelen );
m_free(s);
}
else { /* no filename */
pt = m_alloc( sizeof *pt - 1 );
pt->namelen = 0;
}
}
if( filename && !opt.textmode ) {
if( !(filesize = iobuf_get_filelength(inp)) )
log_info(_("%s: WARNING: empty file\n"), filename );
/* we can't yet encode the length of very large files,
* so we switch to partial length encoding in this case */
if ( filesize >= IOBUF_FILELENGTH_LIMIT )
filesize = 0;
}
else
filesize = opt.set_filesize ? opt.set_filesize : 0; /* stdin */
if (!opt.no_literal) {
pt->timestamp = make_timestamp();
pt->mode = opt.textmode ? 't' : 'b';
pt->len = filesize;
pt->new_ctb = !pt->len && !opt.rfc1991;
pt->buf = inp;
pkt.pkttype = PKT_PLAINTEXT;
pkt.pkt.plaintext = pt;
cfx.datalen = filesize && !do_compress? calc_packet_length( &pkt ) : 0;
}
else
cfx.datalen = filesize && !do_compress ? filesize : 0;
/* register the cipher filter */
iobuf_push_filter( out, cipher_filter, &cfx );
/* register the compress filter */
if( do_compress ) {
int compr_algo = select_algo_from_prefs( pk_list, PREFTYPE_ZIP );
if( !compr_algo )
; /* don't use compression */
else {
if( compr_algo == 1 )
zfx.algo = 1; /* default is 2 */
iobuf_push_filter( out, compress_filter, &zfx );
}
}
/* do the work */
if (!opt.no_literal) {
if( (rc = build_packet( out, &pkt )) )
log_error("build_packet failed: %s\n", g10_errstr(rc) );
}
else {
/* user requested not to create a literal packet, so we copy the plain data */
byte copy_buffer[4096];
int bytes_copied;
while ((bytes_copied = iobuf_read(inp, copy_buffer, 4096)) != -1)
if (iobuf_write(out, copy_buffer, bytes_copied) == -1) {
rc = G10ERR_WRITE_FILE;
log_error("copying input to output failed: %s\n", g10_errstr(rc) );
break;
}
memset(copy_buffer, 0, 4096); /* burn buffer */
}
/* finish the stuff */
leave:
iobuf_close(inp);
if( rc )
iobuf_cancel(out);
else {
iobuf_close(out); /* fixme: check returncode */
write_status( STATUS_END_ENCRYPTION );
}
if( pt )
pt->buf = NULL;
free_packet(&pkt);
m_free(cfx.dek);
release_pk_list( pk_list );
return rc;
}
/****************
* Filter to do a complete public key encryption.
*/
int
encrypt_filter( void *opaque, int control,
IOBUF a, byte *buf, size_t *ret_len)
{
size_t size = *ret_len;
encrypt_filter_context_t *efx = opaque;
int rc=0;
if( control == IOBUFCTRL_UNDERFLOW ) { /* decrypt */
BUG(); /* not used */
}
else if( control == IOBUFCTRL_FLUSH ) { /* encrypt */
if( !efx->header_okay ) {
efx->cfx.dek = m_alloc_secure_clear( sizeof *efx->cfx.dek );
if( !opt.def_cipher_algo ) { /* try to get it from the prefs */
efx->cfx.dek->algo =
select_algo_from_prefs( efx->pk_list, PREFTYPE_SYM );
if( efx->cfx.dek->algo == -1 ) {
/* because 3DES is implicitly in the prefs, this can only
* happen if we do not have any public keys in the list */
efx->cfx.dek->algo = DEFAULT_CIPHER_ALGO;
}
}
else
efx->cfx.dek->algo = opt.def_cipher_algo;
efx->cfx.dek->use_mdc = select_mdc_from_pklist (efx->pk_list);
make_session_key( efx->cfx.dek );
if( DBG_CIPHER )
log_hexdump("DEK is: ",
efx->cfx.dek->key, efx->cfx.dek->keylen );
rc = write_pubkey_enc_from_list( efx->pk_list, efx->cfx.dek, a );
if( rc )
return rc;
iobuf_push_filter( a, cipher_filter, &efx->cfx );
efx->header_okay = 1;
}
rc = iobuf_write( a, buf, size );
}
else if( control == IOBUFCTRL_FREE ) {
}
else if( control == IOBUFCTRL_DESC ) {
*(char**)buf = "encrypt_filter";
}
return rc;
}
/****************
* Write pubkey-enc packets from the list of PKs to OUT.
*/
static int
write_pubkey_enc_from_list( PK_LIST pk_list, DEK *dek, IOBUF out )
{
PACKET pkt;
PKT_public_key *pk;
PKT_pubkey_enc *enc;
int rc;
for( ; pk_list; pk_list = pk_list->next ) {
MPI frame;
pk = pk_list->pk;
print_pubkey_algo_note( pk->pubkey_algo );
enc = m_alloc_clear( sizeof *enc );
enc->pubkey_algo = pk->pubkey_algo;
keyid_from_pk( pk, enc->keyid );
enc->throw_keyid = opt.throw_keyid;
/* Okay, what's going on: We have the session key somewhere in
* the structure DEK and want to encode this session key in
* an integer value of n bits. pubkey_nbits gives us the
* number of bits we have to use. We then encode the session
* key in some way and we get it back in the big intger value
* FRAME. Then we use FRAME, the public key PK->PKEY and the
* algorithm number PK->PUBKEY_ALGO and pass it to pubkey_encrypt
* which returns the encrypted value in the array ENC->DATA.
* This array has a size which depends on the used algorithm
* (e.g. 2 for ElGamal). We don't need frame anymore because we
* have everything now in enc->data which is the passed to
* build_packet()
*/
frame = encode_session_key( dek, pubkey_nbits( pk->pubkey_algo,
pk->pkey ) );
rc = pubkey_encrypt( pk->pubkey_algo, enc->data, frame, pk->pkey );
mpi_free( frame );
if( rc )
log_error("pubkey_encrypt failed: %s\n", g10_errstr(rc) );
else {
if( opt.verbose ) {
char *ustr = get_user_id_string_native( enc->keyid );
log_info(_("%s/%s encrypted for: %s\n"),
pubkey_algo_to_string(enc->pubkey_algo),
cipher_algo_to_string(dek->algo), ustr );
m_free(ustr);
}
/* and write it */
init_packet(&pkt);
pkt.pkttype = PKT_PUBKEY_ENC;
pkt.pkt.pubkey_enc = enc;
rc = build_packet( out, &pkt );
if( rc )
log_error("build_packet(pubkey_enc) failed: %s\n", g10_errstr(rc));
}
free_pubkey_enc(enc);
if( rc )
return rc;
}
return 0;
}
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