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gnupg/g10/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 "trustdb.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( is_RSA(sk->pubkey_algo) )
do_not_use_RSA();
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(_("signing 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, 0 )) )
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;
int compr_algo = -1; /* unknown */
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, PUBKEY_USAGE_SIG )) )
goto leave;
if( !old_style )
old_style = only_old_style( sk_list );
if( encrypt ) {
if( (rc=build_pk_list( remusr, &pk_list, PUBKEY_USAGE_ENC )) )
goto leave;
if( !old_style )
compr_algo = select_algo_from_prefs( pk_list, PREFTYPE_COMPR );
}
/* 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( (rc = open_outfile( fname, opt.armor? 1: detached? 2:0, &out )))
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( detached && !encrypt && !opt.rfc1991 )
afx.what = 2;
if( opt.armor && !outfile )
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( encrypt ) {
efx.pk_list = pk_list;
/* fixme: set efx.cfx.datalen if known */
iobuf_push_filter( out, encrypt_filter, &efx );
}
if( opt.compress && !outfile && ( !detached || opt.compress_sigs) ) {
if( !compr_algo )
; /* don't use compression */
else {
if( old_style || compr_algo == 1 )
zfx.algo = 1;
iobuf_push_filter( out, compress_filter, &zfx );
}
}
if( !detached && !old_style ) {
int skcount=0;
/* loop over the secret certificates and build headers
* The specs now say that the data should be bracket by
* the onepass-sig and signature-packet; so we must build it
* here in reverse order */
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next )
skcount++;
for( ; skcount; skcount-- ) {
PKT_secret_key *sk;
PKT_onepass_sig *ops;
int i = 0;
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next )
if( ++i == skcount )
break;
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 = skcount == 1;
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 || opt.set_filename ) {
char *s = make_basename( opt.set_filename ? opt.set_filename : fname );
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( fname ) {
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
filesize = 0; /* stdin */
pt->timestamp = make_timestamp();
pt->mode = opt.textmode && !outfile ? '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? 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 = old_style || opt.force_v3_sigs ? 3 : 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 calculate the hash over the last CR,LF
*/
static int
write_dash_escaped( IOBUF inp, IOBUF out, MD_HANDLE md )
{
int c;
int lastlf = 1;
int state = 0;
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, ' ' );
}
}
again:
switch( state ) {
case 0:
if( c == '\r' )
state = 1;
else
md_putc(md, c );
break;
case 1:
if( c == '\n' )
state = 2;
else {
md_putc(md, '\r');
state = 0;
goto again;
}
break;
case 2:
md_putc(md, '\r');
md_putc(md, '\n');
state = 0;
goto again;
default: BUG();
}
iobuf_put( out, c );
lastlf = c == '\n';
}
if( state == 1 )
md_putc(md, '\r');
if( !lastlf )
iobuf_put( out, '\n' );
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;
int only_md5 = 0;
memset( &afx, 0, sizeof afx);
memset( &tfx, 0, sizeof tfx);
init_packet( &pkt );
if( (rc=build_sk_list( locusr, &sk_list, 1, PUBKEY_USAGE_SIG )) )
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( (rc = open_outfile( fname, 1, &out )) )
goto leave;
iobuf_writestr(out, "-----BEGIN PGP SIGNED MESSAGE-----\n" );
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk;
if( hash_for(sk->pubkey_algo) == DIGEST_ALGO_MD5 )
only_md5 = 1;
else {
only_md5 = 0;
break;
}
}
if( old_style || only_md5 )
iobuf_writestr(out, "\n" );
else {
const char *s;
int any = 0;
iobuf_writestr(out, "Hash: " );
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk;
s = digest_algo_to_string( hash_for(sk->pubkey_algo) );
if( s ) {
if( any )
iobuf_put(out, ',' );
iobuf_writestr(out, s );
any = 1;
}
}
assert(any);
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;
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 = old_style || opt.force_v3_sigs ? 3 : 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;
}
/****************
* Create a signature packet for the given public key certificate
* and the user id and return it in ret_sig. User signature class SIGCLASS
* user-id is not used (and may be NULL if sigclass is 0x20)
* If digest_algo is 0 the function selects an appropriate one.
*/
int
make_keysig_packet( PKT_signature **ret_sig, PKT_public_key *pk,
PKT_user_id *uid, PKT_public_key *subpk,
PKT_secret_key *sk,
int sigclass, int digest_algo,
int (*mksubpkt)(PKT_signature *, void *), void *opaque
)
{
PKT_signature *sig;
int rc=0;
MD_HANDLE md;
assert( (sigclass >= 0x10 && sigclass <= 0x13)
|| sigclass == 0x20 || sigclass == 0x18 );
if( !digest_algo ) {
switch( sk->pubkey_algo ) {
case PUBKEY_ALGO_DSA: digest_algo = DIGEST_ALGO_SHA1; break;
case PUBKEY_ALGO_RSA_S:
case PUBKEY_ALGO_RSA: digest_algo = DIGEST_ALGO_MD5; break;
default: digest_algo = DIGEST_ALGO_RMD160; break;
}
}
md = md_open( digest_algo, 0 );
/* hash the public key certificate and the user id */
hash_public_key( md, pk );
if( sigclass == 0x18 ) { /* subkey binding */
hash_public_key( md, subpk );
}
else if( sigclass != 0x20 ) {
if( sk->version >=4 ) {
byte buf[5];
buf[0] = 0xb4; /* indicates a userid packet */
buf[1] = uid->len >> 24; /* always use 4 length bytes */
buf[2] = uid->len >> 16;
buf[3] = uid->len >> 8;
buf[4] = uid->len;
md_write( md, buf, 5 );
}
md_write( md, uid->name, uid->len );
}
/* and make the signature packet */
sig = m_alloc_clear( sizeof *sig );
sig->version = sk->version;
keyid_from_sk( sk, sig->keyid );
sig->pubkey_algo = sk->pubkey_algo;
sig->digest_algo = digest_algo;
sig->timestamp = make_timestamp();
sig->sig_class = sigclass;
if( sig->version >= 4 )
build_sig_subpkt_from_sig( sig );
if( sig->version >= 4 && mksubpkt )
rc = (*mksubpkt)( sig, opaque );
if( !rc ) {
if( sig->version >= 4 )
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 = complete_sig( sig, sk, md );
}
md_close( md );
if( rc )
free_seckey_enc( sig );
else
*ret_sig = sig;
return rc;
}
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