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gnupg/g10/sign.c

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/* sign.c - sign data
* Copyright (C) 1998, 1999, 2000 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 <gcrypt.h>
#include "options.h"
#include "packet.h"
#include "errors.h"
#include "iobuf.h"
#include "keydb.h"
#include "util.h"
#include "main.h"
#include "filter.h"
#include "ttyio.h"
#include "trustdb.h"
#include "status.h"
#include "i18n.h"
#define ENABLE_BETTER_PGP2_COMPAT 1
#ifdef HAVE_DOSISH_SYSTEM
#define LF "\r\n"
#else
#define LF "\n"
#endif
/****************
* Emulate our old PK interface here - sometime in the future we might
* change the internal design to directly fit to libgcrypt.
*/
static int
pk_sign( int algo, MPI *data, MPI hash, MPI *skey )
{
GCRY_SEXP s_sig, s_hash, s_skey, list;
int rc;
/* make a sexp from skey */
if( algo == GCRY_PK_DSA ) {
rc = gcry_sexp_build ( &s_skey, NULL,
"(private-key(dsa(p%m)(q%m)(g%m)(y%m)(x%m)))",
skey[0], skey[1], skey[2], skey[3], skey[4] );
}
else if( algo == GCRY_PK_ELG || algo == GCRY_PK_ELG_E ) {
rc = gcry_sexp_build ( &s_skey, NULL,
"(private-key(elg(p%m)(g%m)(y%m)(x%m)))",
skey[0], skey[1], skey[2], skey[3] );
}
else
return GPGERR_PUBKEY_ALGO;
if ( rc )
BUG ();
/* put hash into a S-Exp s_hash */
if ( gcry_sexp_build( &s_hash, NULL, "%m", hash ) )
BUG ();
rc = gcry_pk_sign( &s_sig, s_hash, s_skey );
gcry_sexp_release( s_hash );
gcry_sexp_release( s_skey );
if( rc )
;
else {
list = gcry_sexp_find_token( s_sig, "r" , 0 );
assert( list );
data[0] = gcry_sexp_nth_mpi( list, 1, 0 );
assert( data[0] );
gcry_sexp_release (list);
list = gcry_sexp_find_token( s_sig, "s" , 0 );
assert( list );
data[1] = gcry_sexp_nth_mpi( list, 1, 0 );
assert( data[1] );
gcry_sexp_release (list);
}
gcry_sexp_release( s_sig );
return rc;
}
/****************
* Create a notation. It is assumed that the stings in STRLIST
* are already checked to contain only printable data and have a valid
* NAME=VALUE format.
*/
static void
mk_notation_and_policy( PKT_signature *sig )
{
const char *string, *s;
byte *buf;
unsigned n1, n2;
/* notation data */
if( opt.notation_data && sig->version < 4 )
log_info("can't put notation data into v3 signatures\n");
else if( opt.notation_data ) {
STRLIST nd = opt.notation_data;
for( ; nd; nd = nd->next ) {
string = nd->d;
s = strchr( string, '=' );
if( !s )
BUG(); /* we have already parsed this */
n1 = s - string;
s++;
n2 = strlen(s);
buf = gcry_xmalloc( 8 + n1 + n2 );
buf[0] = 0x80; /* human readable */
buf[1] = buf[2] = buf[3] = 0;
buf[4] = n1 >> 8;
buf[5] = n1;
buf[6] = n2 >> 8;
buf[7] = n2;
memcpy(buf+8, string, n1 );
memcpy(buf+8+n1, s, n2 );
build_sig_subpkt( sig, SIGSUBPKT_NOTATION
| ((nd->flags & 1)? SIGSUBPKT_FLAG_CRITICAL:0),
buf, 8+n1+n2 );
}
}
/* set policy URL */
if( (s=opt.set_policy_url) ) {
if( *s == '!' )
build_sig_subpkt( sig, SIGSUBPKT_POLICY | SIGSUBPKT_FLAG_CRITICAL,
s+1, strlen(s+1) );
else
build_sig_subpkt( sig, SIGSUBPKT_POLICY, s, strlen(s) );
}
}
static int
do_sign( PKT_secret_key *sk, PKT_signature *sig,
GCRY_MD_HD md, int digest_algo )
{
MPI frame;
byte *dp;
int rc;
if( sk->timestamp > sig->timestamp ) {
ulong d = sk->timestamp - sig->timestamp;
log_info( d==1 ? _("key has been created %lu second "
"in future (time warp or clock problem)\n")
: _("key has been created %lu seconds "
"in future (time warp or clock problem)\n"), d );
if( !opt.ignore_time_conflict )
return GPGERR_TIME_CONFLICT;
}
print_pubkey_algo_note(sk->pubkey_algo);
if( !digest_algo )
digest_algo = gcry_md_get_algo(md);
print_digest_algo_note( digest_algo );
dp = gcry_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, gcry_mpi_get_nbits(sk->skey[0]), 0 );
rc = pk_sign( sk->pubkey_algo, sig->data, frame, sk->skey );
mpi_release(frame);
if( rc )
log_error(_("signing failed: %s\n"), gpg_errstr(rc) );
else {
if( opt.verbose ) {
char *ustr = get_user_id_string( sig->keyid );
log_info(_("%s signature from: %s\n"),
gcry_pk_algo_name(sk->pubkey_algo), ustr );
gcry_free(ustr);
}
}
return rc;
}
int
complete_sig( PKT_signature *sig, PKT_secret_key *sk, GCRY_MD_HD 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, int packet_version )
{
if( opt.def_digest_algo )
return opt.def_digest_algo;
if( pubkey_algo == GCRY_PK_DSA )
return GCRY_MD_SHA1;
if( pubkey_algo == GCRY_PK_RSA && packet_version < 4 )
return GCRY_MD_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 == GCRY_PK_RSA && sk->version < 4 )
old_style = 1;
else
return 0;
}
return old_style;
}
static void
print_status_sig_created ( PKT_secret_key *sk, PKT_signature *sig, int what )
{
byte array[MAX_FINGERPRINT_LEN], *p;
char buf[100+MAX_FINGERPRINT_LEN*2];
size_t i, n;
sprintf(buf, "%c %d %d %02x %lu ",
what, sig->pubkey_algo, sig->digest_algo, sig->sig_class,
(ulong)sig->timestamp );
fingerprint_from_sk( sk, array, &n );
p = buf + strlen(buf);
for(i=0; i < n ; i++ )
sprintf(p+2*i, "%02X", array[i] );
write_status_text( STATUS_SIG_CREATED, buf );
}
static int
write_one_signature( IOBUF out, PKT_secret_key *sk, int old_style,
const char *outfile,
GCRY_MD_HD datamd,
int sig_class,
int status_char )
{
PKT_signature *sig;
GCRY_MD_HD md;
int rc;
/* build the signature packet */
/* fixme: this code is partly duplicated in make_keysig_packet */
sig = gcry_xcalloc( 1, 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, sk->version);
sig->pubkey_algo = sk->pubkey_algo;
sig->timestamp = make_timestamp();
sig->sig_class = sig_class;
md = gcry_md_copy( datamd );
if( !md )
BUG();
if( sig->version >= 4 ) {
build_sig_subpkt_from_sig( sig );
gcry_md_putc( md, sig->version );
}
mk_notation_and_policy( sig );
gcry_md_putc( md, sig->sig_class );
if( sig->version < 4 ) {
u32 a = sig->timestamp;
gcry_md_putc( md, (a >> 24) & 0xff );
gcry_md_putc( md, (a >> 16) & 0xff );
gcry_md_putc( md, (a >> 8) & 0xff );
gcry_md_putc( md, a & 0xff );
}
else {
byte buf[6];
size_t n;
gcry_md_putc( md, sig->pubkey_algo );
gcry_md_putc( md, sig->digest_algo );
if( sig->hashed_data ) {
n = (sig->hashed_data[0] << 8) | sig->hashed_data[1];
gcry_md_write( md, sig->hashed_data, n+2 );
n += 6;
}
else {
gcry_md_putc( md, 0 );/* always hash the length of the subpacket*/
gcry_md_putc( md, 0 );
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;
gcry_md_write( md, buf, 6 );
}
gcry_md_final( md );
rc = do_sign( sk, sig, md, hash_for(sig->pubkey_algo, sk->version) );
gcry_md_close( md );
/* Hmmm: Do we release sig in case of rc != 0? */
if( !rc ) { /* and write it */
PACKET pkt;
init_packet(&pkt);
pkt.pkttype = PKT_SIGNATURE;
pkt.pkt.signature = sig;
rc = build_packet( out, &pkt );
if( !rc && is_status_enabled() ) {
print_status_sig_created ( sk, sig, status_char );
}
free_packet( &pkt );
if( rc )
log_error("build signature packet failed: %s\n", gpg_errstr(rc) );
}
return rc;
}
/****************
* 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, GCRY_PK_USAGE_SIGN )) )
goto leave;
if( !old_style )
old_style = only_old_style( sk_list );
if( encrypt ) {
if( (rc=build_pk_list( remusr, &pk_list, GCRY_PK_USAGE_ENCR )) )
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 = GPGERR_OPEN_FILE;
goto leave;
}
if( outfile ) {
if( !(out = iobuf_create( outfile )) ) {
log_error(_("can't create %s: %s\n"), outfile, strerror(errno) );
rc = GPGERR_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 );
if( !(mfx.md = gcry_md_open(0, 0)))
BUG();
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk;
gcry_md_enable(mfx.md, hash_for(sk->pubkey_algo, sk->version ));
}
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 );
}
/* Select a compress algorithm */
if( opt.compress && !outfile && ( !detached || opt.compress_sigs) ) {
if( !compr_algo )
; /* don't use compression */
else {
if( old_style
|| compr_algo == 1
|| (compr_algo == -1 && !encrypt) )
zfx.algo = 1; /* use the non optional algorithm */
iobuf_push_filter( out, compress_filter, &zfx );
}
}
/* Build one-pass signature packets when needed */
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 = gcry_xcalloc( 1, sizeof *ops );
ops->sig_class = opt.textmode && !outfile ? 0x01 : 0x00;
ops->digest_algo = hash_for(sk->pubkey_algo, sk->version);
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",
gpg_errstr(rc));
goto leave;
}
}
}
/* setup the inner packet */
if( detached ) {
/* this is pretty much the same for old and new PGP. So no
* need to cope with different packet ordering */
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 = GPGERR_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 {
/* get the filename to be stored into the literal datapacket */
if (!opt.no_literal) {
if( fname || opt.set_filename ) {
char *s = make_basename( opt.set_filename ?
opt.set_filename : fname );
pt = gcry_xmalloc( sizeof *pt + strlen(s) - 1 );
pt->namelen = strlen(s);
memcpy(pt->name, s, pt->namelen );
gcry_free(s);
}
else { /* no filename */
pt = gcry_xmalloc( sizeof *pt - 1 );
pt->namelen = 0;
}
}
if( fname ) {
if( !(filesize = iobuf_get_filelength(inp)) )
log_info(_("WARNING: `%s' is an empty file\n"), fname );
/* 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;
/* 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.
*/
if( opt.textmode && !outfile )
filesize = 0;
}
else
filesize = opt.set_filesize ? opt.set_filesize : 0; /* stdin */
if (!opt.no_literal) {
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",
gpg_errstr(rc) );
pt->buf = NULL;
}
else {
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 = GPGERR_WRITE_FILE;
log_error("copying input to output failed: %s\n",
gpg_errstr(rc));
break;
}
memset(copy_buffer, 0, 4096); /* burn buffer */
}
}
/* catch errors from above */
if (rc)
goto leave;
/* write all the signature packets */
for( sk_rover = sk_list; sk_rover && !rc ; sk_rover = sk_rover->next ) {
rc = write_one_signature( out, sk_rover->sk,
old_style, outfile, mfx.md,
opt.textmode && !outfile? 0x01 : 0x00,
detached ? 'D':'S' );
}
leave:
if( rc )
iobuf_cancel(out);
else
iobuf_close(out);
iobuf_close(inp);
gcry_md_close( mfx.md );
release_sk_list( sk_list );
release_pk_list( pk_list );
/* FIXME: Did we release the efx.cfx.dek ? */
return rc;
}
/****************
* 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;
GCRY_MD_HD 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);
init_packet( &pkt );
if( (rc=build_sk_list( locusr, &sk_list, 1, GCRY_PK_USAGE_SIGN )) )
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 = GPGERR_OPEN_FILE;
goto leave;
}
if( outfile ) {
if( !(out = iobuf_create( outfile )) ) {
log_error(_("can't create %s: %s\n"), outfile, strerror(errno) );
rc = GPGERR_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-----" LF );
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, sk->version) == GCRY_MD_MD5 )
only_md5 = 1;
else {
only_md5 = 0;
break;
}
}
if( old_style && only_md5 )
iobuf_writestr(out, "\n" );
else {
int any = 0;
byte hashs_seen[256];
memset( hashs_seen, 0, sizeof hashs_seen );
iobuf_writestr(out, "Hash: " );
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk;
int i = hash_for(sk->pubkey_algo, sk->version);
if( !hashs_seen[ i & 0xff ] ) {
if( !openpgp_md_test_algo( i ) ) {
hashs_seen[ i & 0xff ] = 1;
if( any )
iobuf_put(out, ',' );
iobuf_writestr(out, gcry_md_algo_name( i ) );
any = 1;
}
}
}
assert(any);
iobuf_writestr(out, "\n" );
if( opt.not_dash_escaped )
iobuf_writestr( out,
"NotDashEscaped: You need GnuPG to verify this message\n" );
iobuf_writestr(out, "\n" );
}
textmd = gcry_md_open(0, 0);
if( !textmd )
BUG();
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk;
gcry_md_enable(textmd, hash_for(sk->pubkey_algo, sk->version));
}
if ( DBG_HASHING )
gcry_md_start_debug( textmd, "clearsign" );
copy_clearsig_text( out, inp, textmd,
!opt.not_dash_escaped, opt.escape_from, old_style );
/* fixme: check for read errors */
/* now write the armor */
afx.what = 2;
iobuf_push_filter( out, armor_filter, &afx );
/* write all the signature packets */
for( sk_rover = sk_list; sk_rover && !rc ; sk_rover = sk_rover->next ) {
rc = write_one_signature( out, sk_rover->sk,
old_style, outfile, textmd,
0x01,
'C' );
}
leave:
if( rc )
iobuf_cancel(out);
else
iobuf_close(out);
iobuf_close(inp);
gcry_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;
GCRY_MD_HD md;
assert( (sigclass >= 0x10 && sigclass <= 0x13)
|| sigclass == 0x20 || sigclass == 0x18
|| sigclass == 0x30 || sigclass == 0x28 );
if( !digest_algo ) {
switch( sk->pubkey_algo ) {
case GCRY_PK_DSA: digest_algo = GCRY_MD_SHA1; break;
case GCRY_PK_RSA_S:
case GCRY_PK_RSA: digest_algo = GCRY_MD_MD5; break;
default: digest_algo = GCRY_MD_RMD160; break;
}
}
if( !(md = gcry_md_open( digest_algo, 0 )))
BUG();
/* hash the public key certificate and the user id */
hash_public_key( md, pk );
if( sigclass == 0x18 || sigclass == 0x28 ) { /* subkey binding/revocation*/
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;
gcry_md_write( md, buf, 5 );
}
gcry_md_write( md, uid->name, uid->len );
}
/* and make the signature packet */
sig = gcry_xcalloc( 1, 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 ) {
mk_notation_and_policy( sig );
if( sig->version >= 4 )
gcry_md_putc( md, sig->version );
gcry_md_putc( md, sig->sig_class );
if( sig->version < 4 ) {
u32 a = sig->timestamp;
gcry_md_putc( md, (a >> 24) & 0xff );
gcry_md_putc( md, (a >> 16) & 0xff );
gcry_md_putc( md, (a >> 8) & 0xff );
gcry_md_putc( md, a & 0xff );
}
else {
byte buf[6];
size_t n;
gcry_md_putc( md, sig->pubkey_algo );
gcry_md_putc( md, sig->digest_algo );
if( sig->hashed_data ) {
n = (sig->hashed_data[0] << 8) | sig->hashed_data[1];
gcry_md_write( md, sig->hashed_data, n+2 );
n += 6;
}
else {
gcry_md_putc( md, 0 ); /* always hash the length of the subpacket*/
gcry_md_putc( md, 0 );
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;
gcry_md_write( md, buf, 6 );
}
gcry_md_final(md);
rc = complete_sig( sig, sk, md );
}
gcry_md_close( md );
if( rc )
free_seckey_enc( sig );
else
*ret_sig = sig;
return rc;
}
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