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passphrase.c
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/* passphrase.c - Get a passphrase
* 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 <unistd.h>
#include <assert.h>
#include "util.h"
#include "memory.h"
#include "options.h"
#include "ttyio.h"
#include "cipher.h"
#include "keydb.h"
#include "main.h"
#include "i18n.h"
#include "status.h"
static char *fd_passwd = NULL;
static char *next_pw = NULL;
static char *last_pw = NULL;
static void hash_passphrase( DEK *dek, char *pw, STRING2KEY *s2k, int create );
int
have_static_passphrase()
{
return !!fd_passwd;
}
/****************
* Set the passphrase to be used for the next query and only for the next
* one.
*/
void
set_next_passphrase( const char *s )
{
m_free(next_pw);
next_pw = NULL;
if( s ) {
next_pw = m_alloc_secure( strlen(s)+1 );
strcpy(next_pw, s );
}
}
/****************
* Get the last passphrase used in passphrase_to_dek.
* Note: This removes the passphrase from this modules and
* the caller must free the result. May return NULL:
*/
char *
get_last_passphrase()
{
char *p = last_pw;
last_pw = NULL;
return p;
}
void
read_passphrase_from_fd( int fd )
{
int i, len;
char *pw;
if( !opt.batch )
tty_printf("Reading passphrase from file descriptor %d ...", fd );
for( pw = NULL, i = len = 100; ; i++ ) {
if( i >= len-1 ) {
char *pw2 = pw;
len += 100;
pw = m_alloc_secure( len );
if( pw2 )
memcpy(pw, pw2, i );
else
i=0;
}
if( read( fd, pw+i, 1) != 1 || pw[i] == '\n' )
break;
}
pw[i] = 0;
if( !opt.batch )
tty_printf("\b\b\b \n" );
m_free( fd_passwd );
fd_passwd = pw;
}
/****************
* Get a passphrase for the secret key with KEYID, display TEXT
* if the user needs to enter the passphrase.
* mode 0 = standard, 2 = create new passphrase
* Returns: a DEK with a session key; caller must free
* or NULL if the passphrase was not correctly repeated.
* (only for mode 2)
* a dek->keylen of 0 means: no passphrase entered.
* (only for mode 2)
* pubkey_algo is only informational.
*/
DEK *
passphrase_to_dek( u32 *keyid, int pubkey_algo,
int cipher_algo, STRING2KEY *s2k, int mode )
{
char *pw = NULL;
DEK *dek;
STRING2KEY help_s2k;
if( !s2k ) {
s2k = &help_s2k;
s2k->mode = 0;
/* this should be MD5 if cipher is IDEA, but because we do
* not have IDEA, we use the default one, the user
* can select it from the commandline
*/
s2k->hash_algo = opt.def_digest_algo?opt.def_digest_algo
:DEFAULT_DIGEST_ALGO;
}
if( !next_pw && is_status_enabled() ) {
char buf[50];
if( keyid ) {
sprintf( buf, "%08lX%08lX", (ulong)keyid[0], (ulong)keyid[1] );
if( keyid[2] && keyid[3] && keyid[0] != keyid[2]
&& keyid[1] != keyid[3] )
sprintf( buf+strlen(buf), " %08lX%08lX %d 0",
(ulong)keyid[2], (ulong)keyid[3], pubkey_algo );
write_status_text( STATUS_NEED_PASSPHRASE, buf );
}
else {
sprintf( buf, "%d %d %d", cipher_algo, s2k->mode, s2k->hash_algo );
write_status_text( STATUS_NEED_PASSPHRASE_SYM, buf );
}
}
if( keyid && !opt.batch && !next_pw ) {
PKT_public_key *pk = m_alloc_clear( sizeof *pk );
size_t n;
char *p;
tty_printf(_("\nYou need a passphrase to unlock the secret key for\n"
"user: \"") );
p = get_user_id( keyid, &n );
tty_print_string( p, n );
m_free(p);
tty_printf("\"\n");
if( !get_pubkey( pk, keyid ) ) {
const char *s = pubkey_algo_to_string( pk->pubkey_algo );
tty_printf( _("%u-bit %s key, ID %08lX, created %s"),
nbits_from_pk( pk ), s?s:"?", (ulong)keyid[1],
strtimestamp(pk->timestamp) );
if( keyid[2] && keyid[3] && keyid[0] != keyid[2]
&& keyid[1] != keyid[3] )
tty_printf( _(" (main key ID %08lX)"), (ulong)keyid[3] );
tty_printf("\n");
}
tty_printf("\n");
free_public_key( pk );
}
if( next_pw ) {
pw = next_pw;
next_pw = NULL;
}
else if( fd_passwd ) {
pw = m_alloc_secure( strlen(fd_passwd)+1 );
strcpy( pw, fd_passwd );
}
else if( opt.batch ) {
log_error(_("can't query password in batchmode\n"));
pw = m_strdup( "" ); /* return an empty passphrase */
}
else {
pw = cpr_get_hidden("passphrase.enter", _("Enter passphrase: ") );
tty_kill_prompt();
if( mode == 2 && !cpr_enabled() ) {
char *pw2 = cpr_get_hidden("passphrase.repeat",
_("Repeat passphrase: ") );
tty_kill_prompt();
if( strcmp(pw, pw2) ) {
m_free(pw2);
m_free(pw);
return NULL;
}
m_free(pw2);
}
}
if( !pw || !*pw )
write_status( STATUS_MISSING_PASSPHRASE );
dek = m_alloc_secure( sizeof *dek );
dek->algo = cipher_algo;
if( !*pw && mode == 2 )
dek->keylen = 0;
else
hash_passphrase( dek, pw, s2k, mode==2 );
m_free(last_pw);
last_pw = pw;
return dek;
}
/****************
* Hash a passphrase using the supplied s2k. If create is true, create
* a new salt or what else must be filled into the s2k for a new key.
* always needs: dek->algo, s2k->mode, s2k->hash_algo.
*/
static void
hash_passphrase( DEK *dek, char *pw, STRING2KEY *s2k, int create )
{
MD_HANDLE md;
int pass, i;
int used = 0;
int pwlen = strlen(pw);
assert( s2k->hash_algo );
dek->keylen = cipher_get_keylen( dek->algo ) / 8;
if( !(dek->keylen > 0 && dek->keylen <= DIM(dek->key)) )
BUG();
md = md_open( s2k->hash_algo, 1);
for(pass=0; used < dek->keylen ; pass++ ) {
if( pass ) {
md_reset(md);
for(i=0; i < pass; i++ ) /* preset the hash context */
md_putc(md, 0 );
}
if( s2k->mode == 1 || s2k->mode == 3 ) {
int len2 = pwlen + 8;
ulong count = len2;
if( create && !pass ) {
randomize_buffer(s2k->salt, 8, 1);
if( s2k->mode == 3 )
s2k->count = 96; /* 65536 iterations */
}
if( s2k->mode == 3 ) {
count = (16ul + (s2k->count & 15)) << ((s2k->count >> 4) + 6);
if( count < len2 )
count = len2;
}
/* a little bit complicated because we need a ulong for count */
while( count > len2 ) { /* maybe iterated+salted */
md_write( md, s2k->salt, 8 );
md_write( md, pw, pwlen );
count -= len2;
}
if( count < 8 )
md_write( md, s2k->salt, count );
else {
md_write( md, s2k->salt, 8 );
count -= 8;
assert( count >= 0 );
md_write( md, pw, count );
}
}
else
md_write( md, pw, pwlen );
md_final( md );
i = md_digest_length( s2k->hash_algo );
if( i > dek->keylen - used )
i = dek->keylen - used;
memcpy( dek->key+used, md_read(md, s2k->hash_algo), i );
used += i;
}
md_close(md);
}

File Metadata

Mime Type
text/x-c
Expires
Tue, Apr 22, 4:01 AM (29 m, 17 s)
Storage Engine
local-disk
Storage Format
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Storage Handle
bd/20/c8e194a4f5b87c2f0ee40750563b

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