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sign.c
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/* sign.c - sign data
* Copyright (C) 1998 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 "ttyio.h"
#include "i18n.h"
static int
do_sign( PKT_secret_key *sk, PKT_signature *sig,
MD_HANDLE md, int digest_algo )
{
MPI frame;
byte *dp;
int rc;
if( !digest_algo )
digest_algo = md_get_algo(md);
dp = md_read( md, digest_algo );
sig->digest_algo = digest_algo;
sig->digest_start[0] = dp[0];
sig->digest_start[1] = dp[1];
frame = encode_md_value( sk->pubkey_algo, md,
digest_algo, mpi_get_nbits(sk->skey[0]));
rc = pubkey_sign( sk->pubkey_algo, sig->data, frame, sk->skey );
mpi_free(frame);
if( rc )
log_error("pubkey_sign failed: %s\n", g10_errstr(rc) );
else {
if( opt.verbose ) {
char *ustr = get_user_id_string( sig->keyid );
log_info("%s signature from: %s\n",
pubkey_algo_to_string(sk->pubkey_algo), ustr );
m_free(ustr);
}
}
return rc;
}
int
complete_sig( PKT_signature *sig, PKT_secret_key *sk, MD_HANDLE md )
{
int rc=0;
if( !(rc=check_secret_key( sk )) )
rc = do_sign( sk, sig, md, 0 );
/* fixme: should we check whether the signature is okay?
* maybe by using an option */
return rc;
}
static int
hash_for(int pubkey_algo )
{
if( opt.def_digest_algo )
return opt.def_digest_algo;
if( pubkey_algo == PUBKEY_ALGO_DSA )
return DIGEST_ALGO_SHA1;
if( pubkey_algo == PUBKEY_ALGO_RSA )
return DIGEST_ALGO_MD5;
return DEFAULT_DIGEST_ALGO;
}
static int
only_old_style( SK_LIST sk_list )
{
SK_LIST sk_rover = NULL;
int old_style = 0;
/* if there are only old style capable key we use the old sytle */
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk;
if( sk->pubkey_algo == PUBKEY_ALGO_RSA && sk->version < 4 )
old_style = 1;
else
return 0;
}
return old_style;
}
/****************
* Sign the files whose names are in FILENAME.
* If DETACHED has the value true,
* make a detached signature. If FILENAMES->d is NULL read from stdin
* and ignore the detached mode. Sign the file with all secret keys
* which can be taken from LOCUSR, if this is NULL, use the default one
* If ENCRYPT is true, use REMUSER (or ask if it is NULL) to encrypt the
* signed data for these users.
* If OUTFILE is not NULL; this file is used for output and the function
* does not ask for overwrite permission; output is then always
* uncompressed, non-armored and in binary mode.
*/
int
sign_file( STRLIST filenames, int detached, STRLIST locusr,
int encrypt, STRLIST remusr, const char *outfile )
{
const char *fname;
armor_filter_context_t afx;
compress_filter_context_t zfx;
md_filter_context_t mfx;
text_filter_context_t tfx;
encrypt_filter_context_t efx;
IOBUF inp = NULL, out = NULL;
PACKET pkt;
PKT_plaintext *pt = NULL;
u32 filesize;
int rc = 0;
PK_LIST pk_list = NULL;
SK_LIST sk_list = NULL;
SK_LIST sk_rover = NULL;
int multifile = 0;
int old_style = opt.rfc1991;
memset( &afx, 0, sizeof afx);
memset( &zfx, 0, sizeof zfx);
memset( &mfx, 0, sizeof mfx);
memset( &tfx, 0, sizeof tfx);
memset( &efx, 0, sizeof efx);
init_packet( &pkt );
if( filenames ) {
fname = filenames->d;
multifile = !!filenames->next;
}
else
fname = NULL;
if( fname && filenames->next && (!detached || encrypt) )
log_bug("multiple files can only be detached signed");
if( (rc=build_sk_list( locusr, &sk_list, 1, 1 )) )
goto leave;
if( !old_style )
old_style = only_old_style( sk_list );
if( encrypt ) {
if( (rc=build_pk_list( remusr, &pk_list, 2 )) )
goto leave;
}
/* prepare iobufs */
if( multifile ) /* have list of filenames */
inp = NULL; /* we do it later */
else if( !(inp = iobuf_open(fname)) ) {
log_error("can't open %s: %s\n", fname? fname: "[stdin]",
strerror(errno) );
rc = G10ERR_OPEN_FILE;
goto leave;
}
if( outfile ) {
if( !(out = iobuf_create( outfile )) ) {
log_error("can't create %s: %s\n", outfile, strerror(errno) );
rc = G10ERR_CREATE_FILE;
goto leave;
}
else if( opt.verbose )
log_info("writing to '%s'\n", outfile );
}
else if( !(out = open_outfile( fname, opt.armor? 1: detached? 2:0 )) ) {
rc = G10ERR_CREATE_FILE;
goto leave;
}
/* prepare to calculate the MD over the input */
if( opt.textmode && !outfile )
iobuf_push_filter( inp, text_filter, &tfx );
mfx.md = md_open(0, 0);
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk;
md_enable(mfx.md, hash_for(sk->pubkey_algo));
}
if( !multifile )
iobuf_push_filter( inp, md_filter, &mfx );
if( opt.armor && !outfile )
iobuf_push_filter( out, armor_filter, &afx );
else
write_comment( out, "#created by GNUPG v" VERSION " ("
PRINTABLE_OS_NAME ")");
if( encrypt ) {
efx.pk_list = pk_list;
/* fixme: set efx.cfx.datalen if known */
iobuf_push_filter( out, encrypt_filter, &efx );
}
if( opt.compress && !outfile ) {
if( old_style )
zfx.algo = 1;
iobuf_push_filter( out, compress_filter, &zfx );
}
if( !detached && !old_style ) {
/* loop over the secret certificates and build headers */
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk;
PKT_onepass_sig *ops;
sk = sk_rover->sk;
ops = m_alloc_clear( sizeof *ops );
ops->sig_class = opt.textmode && !outfile ? 0x01 : 0x00;
ops->digest_algo = hash_for(sk->pubkey_algo);
ops->pubkey_algo = sk->pubkey_algo;
keyid_from_sk( sk, ops->keyid );
ops->last = !sk_rover->next;
init_packet(&pkt);
pkt.pkttype = PKT_ONEPASS_SIG;
pkt.pkt.onepass_sig = ops;
rc = build_packet( out, &pkt );
free_packet( &pkt );
if( rc ) {
log_error("build onepass_sig packet failed: %s\n",
g10_errstr(rc));
goto leave;
}
}
}
/* setup the inner packet */
if( detached ) {
if( multifile ) {
STRLIST sl;
if( opt.verbose )
log_info("signing:" );
/* must walk reverse trough this list */
for( sl = strlist_last(filenames); sl;
sl = strlist_prev( filenames, sl ) ) {
if( !(inp = iobuf_open(sl->d)) ) {
log_error("can't open %s: %s\n", sl->d, strerror(errno) );
rc = G10ERR_OPEN_FILE;
goto leave;
}
if( opt.verbose )
fprintf(stderr, " '%s'", sl->d );
iobuf_push_filter( inp, md_filter, &mfx );
while( iobuf_get(inp) != -1 )
;
iobuf_close(inp); inp = NULL;
}
if( opt.verbose )
putc( '\n', stderr );
}
else {
/* read, so that the filter can calculate the digest */
while( iobuf_get(inp) != -1 )
;
}
}
else {
if( fname ) {
pt = m_alloc( sizeof *pt + strlen(fname) - 1 );
pt->namelen = strlen(fname);
memcpy(pt->name, fname, pt->namelen );
if( !(filesize = iobuf_get_filelength(inp)) )
log_info("warning: '%s' is an empty file\n", fname );
/* because the text_filter modifies the length of the
* data, it is not possible to know the used length
* without a double read of the file - to avoid that
* we simple use partial length packets.
* FIXME: We have to do the double read when opt.rfc1991
* is active.
*/
if( opt.textmode && !outfile )
filesize = 0;
}
else { /* no filename */
pt = m_alloc( sizeof *pt - 1 );
pt->namelen = 0;
filesize = 0; /* stdin */
}
pt->timestamp = make_timestamp();
pt->mode = opt.textmode && !outfile ? 't':'b';
pt->len = filesize;
pt->buf = inp;
pkt.pkttype = PKT_PLAINTEXT;
pkt.pkt.plaintext = pt;
/*cfx.datalen = filesize? calc_packet_length( &pkt ) : 0;*/
if( (rc = build_packet( out, &pkt )) )
log_error("build_packet(PLAINTEXT) failed: %s\n", g10_errstr(rc) );
pt->buf = NULL;
}
/* loop over the secret certificates */
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk;
PKT_signature *sig;
MD_HANDLE md;
sk = sk_rover->sk;
/* build the signature packet */
/* fixme: this code is partly duplicated in make_keysig_packet */
sig = m_alloc_clear( sizeof *sig );
sig->version = sk->version;
keyid_from_sk( sk, sig->keyid );
sig->digest_algo = hash_for(sk->pubkey_algo);
sig->pubkey_algo = sk->pubkey_algo;
sig->timestamp = make_timestamp();
sig->sig_class = opt.textmode && !outfile? 0x01 : 0x00;
md = md_copy( mfx.md );
if( sig->version >= 4 ) {
build_sig_subpkt_from_sig( sig );
md_putc( md, sig->version );
}
md_putc( md, sig->sig_class );
if( sig->version < 4 ) {
u32 a = sig->timestamp;
md_putc( md, (a >> 24) & 0xff );
md_putc( md, (a >> 16) & 0xff );
md_putc( md, (a >> 8) & 0xff );
md_putc( md, a & 0xff );
}
else {
byte buf[6];
size_t n;
md_putc( md, sig->pubkey_algo );
md_putc( md, sig->digest_algo );
if( sig->hashed_data ) {
n = (sig->hashed_data[0] << 8) | sig->hashed_data[1];
md_write( md, sig->hashed_data, n+2 );
n += 6;
}
else
n = 6;
/* add some magic */
buf[0] = sig->version;
buf[1] = 0xff;
buf[2] = n >> 24; /* hmmm, n is only 16 bit, so this is always 0 */
buf[3] = n >> 16;
buf[4] = n >> 8;
buf[5] = n;
md_write( md, buf, 6 );
}
md_final( md );
rc = do_sign( sk, sig, md, hash_for(sig->pubkey_algo) );
md_close( md );
if( !rc ) { /* and write it */
init_packet(&pkt);
pkt.pkttype = PKT_SIGNATURE;
pkt.pkt.signature = sig;
rc = build_packet( out, &pkt );
free_packet( &pkt );
if( rc )
log_error("build signature packet failed: %s\n", g10_errstr(rc) );
}
if( rc )
goto leave;
}
leave:
if( rc )
iobuf_cancel(out);
else
iobuf_close(out);
iobuf_close(inp);
md_close( mfx.md );
release_sk_list( sk_list );
release_pk_list( pk_list );
return rc;
}
/****************
* note: we do not count empty lines at the beginning
*/
static int
write_dash_escaped( IOBUF inp, IOBUF out, MD_HANDLE md )
{
int c;
int lastlf = 1;
int skip_empty = 1;
while( (c = iobuf_get(inp)) != -1 ) {
/* Note: We don't escape "From " because the MUA should cope with it */
if( lastlf ) {
if( c == '-' ) {
iobuf_put( out, c );
iobuf_put( out, ' ' );
skip_empty = 0;
}
else if( skip_empty && c == '\r' )
skip_empty = 2;
else
skip_empty = 0;
}
if( !skip_empty )
md_putc(md, c );
iobuf_put( out, c );
lastlf = c == '\n';
if( skip_empty == 2 )
skip_empty = lastlf ? 0 : 1;
}
return 0; /* fixme: add error handling */
}
/****************
* make a clear signature. note that opt.armor is not needed
*/
int
clearsign_file( const char *fname, STRLIST locusr, const char *outfile )
{
armor_filter_context_t afx;
text_filter_context_t tfx;
MD_HANDLE textmd = NULL;
IOBUF inp = NULL, out = NULL;
PACKET pkt;
int rc = 0;
SK_LIST sk_list = NULL;
SK_LIST sk_rover = NULL;
int old_style = opt.rfc1991;
memset( &afx, 0, sizeof afx);
memset( &tfx, 0, sizeof tfx);
init_packet( &pkt );
if( (rc=build_sk_list( locusr, &sk_list, 1, 1 )) )
goto leave;
if( !old_style )
old_style = only_old_style( sk_list );
/* prepare iobufs */
if( !(inp = iobuf_open(fname)) ) {
log_error("can't open %s: %s\n", fname? fname: "[stdin]",
strerror(errno) );
rc = G10ERR_OPEN_FILE;
goto leave;
}
if( outfile ) {
if( !(out = iobuf_create( outfile )) ) {
log_error("can't create %s: %s\n", outfile, strerror(errno) );
rc = G10ERR_CREATE_FILE;
goto leave;
}
else if( opt.verbose )
log_info("writing to '%s'\n", outfile );
}
else if( !(out = open_outfile( fname, 1 )) ) {
rc = G10ERR_CREATE_FILE;
goto leave;
}
/* FIXME: This stuff is not correct if multiple hash algos are used*/
iobuf_writestr(out, "-----BEGIN PGP SIGNED MESSAGE-----\n" );
if( old_style
|| (opt.def_digest_algo?opt.def_digest_algo:DEFAULT_DIGEST_ALGO)
== DIGEST_ALGO_MD5 )
iobuf_writestr(out, "\n" );
else {
const char *s = digest_algo_to_string(opt.def_digest_algo?
opt.def_digest_algo:DEFAULT_DIGEST_ALGO);
assert(s);
iobuf_writestr(out, "Hash: " );
iobuf_writestr(out, s );
iobuf_writestr(out, "\n\n" );
}
textmd = md_open(0, 0);
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk;
md_enable(textmd, hash_for(sk->pubkey_algo));
}
iobuf_push_filter( inp, text_filter, &tfx );
rc = write_dash_escaped( inp, out, textmd );
if( rc )
goto leave;
iobuf_writestr(out, "\n" );
afx.what = 2;
iobuf_push_filter( out, armor_filter, &afx );
/* loop over the secret certificates */
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk;
PKT_signature *sig;
MD_HANDLE md;
sk = sk_rover->sk;
/* build the signature packet */
/* fixme: this code is duplicated above */
sig = m_alloc_clear( sizeof *sig );
sig->version = sk->version;
keyid_from_sk( sk, sig->keyid );
sig->digest_algo = hash_for(sk->pubkey_algo);
sig->pubkey_algo = sk->pubkey_algo;
sig->timestamp = make_timestamp();
sig->sig_class = 0x01;
md = md_copy( textmd );
if( sig->version >= 4 ) {
build_sig_subpkt_from_sig( sig );
md_putc( md, sig->version );
}
md_putc( md, sig->sig_class );
if( sig->version < 4 ) {
u32 a = sig->timestamp;
md_putc( md, (a >> 24) & 0xff );
md_putc( md, (a >> 16) & 0xff );
md_putc( md, (a >> 8) & 0xff );
md_putc( md, a & 0xff );
}
else {
byte buf[6];
size_t n;
md_putc( md, sig->pubkey_algo );
md_putc( md, sig->digest_algo );
if( sig->hashed_data ) {
n = (sig->hashed_data[0] << 8) | sig->hashed_data[1];
md_write( md, sig->hashed_data, n+2 );
n += 6;
}
else
n = 6;
/* add some magic */
buf[0] = sig->version;
buf[1] = 0xff;
buf[2] = n >> 24; /* hmmm, n is only 16 bit, so this is always 0 */
buf[3] = n >> 16;
buf[4] = n >> 8;
buf[5] = n;
md_write( md, buf, 6 );
}
md_final( md );
rc = do_sign( sk, sig, md, hash_for(sig->pubkey_algo) );
md_close( md );
if( !rc ) { /* and write it */
init_packet(&pkt);
pkt.pkttype = PKT_SIGNATURE;
pkt.pkt.signature = sig;
rc = build_packet( out, &pkt );
free_packet( &pkt );
if( rc )
log_error("build signature packet failed: %s\n", g10_errstr(rc) );
}
if( rc )
goto leave;
}
leave:
if( rc )
iobuf_cancel(out);
else
iobuf_close(out);
iobuf_close(inp);
md_close( textmd );
release_sk_list( sk_list );
return rc;
}

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