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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"
static int pwfd = -1;
static void hash_passphrase( DEK *dek, char *pw, STRING2KEY *s2k, int create );
void
set_passphrase_fd( int fd )
{
pwfd = fd;
}
int
get_passphrase_fd()
{
return pwfd;
}
/****************
* 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)
*/
DEK *
passphrase_to_dek( u32 *keyid, int cipher_algo, STRING2KEY *s2k, int mode )
{
char *pw;
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 the user
* can select it from the commandline
*/
s2k->hash_algo = opt.def_digest_algo;
}
if( keyid && !opt.batch ) {
char *ustr;
tty_printf("Need a pass phrase to unlock the secret key for:\n");
tty_printf(" \"" );
ustr = get_user_id_string( keyid );
tty_print_string( ustr, strlen(ustr) );
m_free(ustr);
tty_printf("\"\n\n");
}
if( pwfd != -1 ) { /* read the passphrase from the given descriptor */
int i, len;
if( !opt.batch )
tty_printf("Reading from file descriptor %d ...", pwfd );
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 );
i=0;
}
if( read( pwfd, pw+i, 1) != 1 || pw[i] == '\n' )
break;
}
pw[i] = 0;
if( !opt.batch )
tty_printf("\b\b\b \n" );
}
else if( opt.batch )
log_fatal("Can't query password in batchmode\n");
else {
pw = tty_get_hidden("Enter pass phrase: " );
tty_kill_prompt();
if( mode == 2 ) {
char *pw2 = tty_get_hidden("Repeat pass phrase: " );
tty_kill_prompt();
if( strcmp(pw, pw2) ) {
m_free(pw2);
m_free(pw);
return NULL;
}
m_free(pw2);
}
}
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(pw); /* is allocated in secure memory, so it will be burned */
return dek;
}
/****************
* Hash a passphrase using the supplied s2k. If create is true, create
* a new salt or whatelse 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;
assert( s2k->hash_algo );
dek->keylen = 0;
md = md_open( s2k->hash_algo, 1);
if( s2k->mode == 1 || s2k->mode == 4 ) {
if( create )
randomize_buffer(s2k->salt, 8, 1);
md_write( md, s2k->salt, 8 );
}
md_write( md, pw, strlen(pw) );
md_final( md );
dek->keylen = cipher_get_keylen( dek->algo ) / 8;
assert(dek->keylen > 0 && dek->keylen <= DIM(dek->key) );
memcpy( dek->key, md_read(md,0), dek->keylen );
md_close(md);
}
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