mirror of git://git.gnupg.org/gnupg.git
330 lines
8.8 KiB
C
330 lines
8.8 KiB
C
/* seckey-cert.c - secret key certifucate packet handling
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* Copyright (C) 1998 Free Software Foundation, Inc.
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*
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* This file is part of GNUPG.
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*
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* GNUPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GNUPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include "util.h"
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#include "memory.h"
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#include "packet.h"
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#include "mpi.h"
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#include "keydb.h"
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#include "cipher.h"
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#if BLOWFISH_BLOCKSIZE != 8
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#error unsupportted blocksize
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#endif
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static u16
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checksum_u16( unsigned n )
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{
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u16 a;
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a = (n >> 8) & 0xff;
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a |= n & 0xff;
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return a;
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}
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static u16
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checksum( byte *p, unsigned n )
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{
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u16 a;
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for(a=0; n; n-- )
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a += *p++;
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return a;
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}
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static int
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check_elg( PKT_secret_cert *cert )
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{
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byte *buffer;
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u16 csum=0;
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int res;
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unsigned nbytes;
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u32 keyid[2];
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ELG_secret_key skey;
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char save_iv[8];
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if( cert->d.elg.is_protected ) { /* remove the protection */
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DEK *dek = NULL;
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MPI test_x;
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BLOWFISH_context *blowfish_ctx=NULL;
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switch( cert->d.elg.protect.algo ) {
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case CIPHER_ALGO_NONE: BUG(); break;
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case CIPHER_ALGO_BLOWFISH:
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keyid_from_skc( cert, keyid );
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if( cert->d.elg.protect.s2k == 1
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|| cert->d.elg.protect.s2k == 3 )
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dek = get_passphrase_hash( keyid, NULL,
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cert->d.elg.protect.salt );
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else
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dek = get_passphrase_hash( keyid, NULL, NULL );
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blowfish_ctx = m_alloc_secure( sizeof *blowfish_ctx );
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blowfish_setkey( blowfish_ctx, dek->key, dek->keylen );
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m_free(dek); /* pw is in secure memory, so m_free() burns it */
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blowfish_setiv( blowfish_ctx, NULL );
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memcpy(save_iv, cert->d.elg.protect.iv, 8 );
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blowfish_decode_cfb( blowfish_ctx,
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cert->d.elg.protect.iv,
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cert->d.elg.protect.iv, 8 );
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mpi_set_secure(cert->d.elg.x );
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/*fixme: maybe it is better to set the buffer secure with a
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* new get_buffer_secure() function */
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buffer = mpi_get_buffer( cert->d.elg.x, &nbytes, NULL );
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csum = checksum_u16( nbytes*8 );
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blowfish_decode_cfb( blowfish_ctx, buffer, buffer, nbytes );
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csum += checksum( buffer, nbytes );
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test_x = mpi_alloc_secure( mpi_get_nlimbs(cert->d.elg.x) );
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mpi_set_buffer( test_x, buffer, nbytes, 0 );
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m_free( buffer );
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m_free( blowfish_ctx );
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/* now let's see wether we have used the right passphrase */
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if( csum != cert->d.elg.csum ) {
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mpi_free(test_x);
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memcpy( cert->d.elg.protect.iv, save_iv, 8 );
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return G10ERR_BAD_PASS;
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}
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skey.p = cert->d.elg.p;
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skey.g = cert->d.elg.g;
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skey.y = cert->d.elg.y;
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skey.x = test_x;
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res = elg_check_secret_key( &skey );
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memset( &skey, 0, sizeof skey );
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if( !res ) {
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mpi_free(test_x);
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memcpy( cert->d.elg.protect.iv, save_iv, 8 );
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return G10ERR_BAD_PASS;
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}
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mpi_set(cert->d.elg.x, test_x);
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mpi_free(test_x);
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cert->d.elg.is_protected = 0;
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break;
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default:
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return G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */
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}
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}
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else { /* not protected */
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buffer = mpi_get_buffer( cert->d.elg.x, &nbytes, NULL );
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csum = checksum_u16( nbytes*8 );
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csum += checksum( buffer, nbytes );
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m_free( buffer );
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if( csum != cert->d.elg.csum )
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return G10ERR_CHECKSUM;
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}
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return 0;
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}
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static int
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protect_elg( PKT_secret_cert *cert, DEK *dek )
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{
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byte *buffer;
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unsigned nbytes;
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if( !cert->d.elg.is_protected ) { /* add the protection */
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BLOWFISH_context *blowfish_ctx=NULL;
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switch( cert->d.elg.protect.algo ) {
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case CIPHER_ALGO_NONE: BUG(); break;
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case CIPHER_ALGO_BLOWFISH:
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blowfish_ctx = m_alloc_secure( sizeof *blowfish_ctx );
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blowfish_setkey( blowfish_ctx, dek->key, dek->keylen );
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blowfish_setiv( blowfish_ctx, NULL );
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blowfish_encode_cfb( blowfish_ctx,
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cert->d.elg.protect.iv,
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cert->d.elg.protect.iv, 8 );
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buffer = mpi_get_buffer( cert->d.elg.x, &nbytes, NULL );
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blowfish_encode_cfb( blowfish_ctx, buffer, buffer, nbytes );
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mpi_set_buffer( cert->d.elg.x, buffer, nbytes, 0 );
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m_free( buffer );
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m_free( blowfish_ctx );
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cert->d.elg.is_protected = 1;
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break;
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default:
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return G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */
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}
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}
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return 0;
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}
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#ifdef HAVE_RSA_CIPHER
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static int
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check_rsa( PKT_secret_cert *cert )
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{
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byte *buffer;
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u16 csum=0;
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int res;
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unsigned nbytes;
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u32 keyid[2];
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RSA_secret_key skey;
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if( cert->d.rsa.is_protected ) { /* remove the protection */
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DEK *dek = NULL;
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BLOWFISH_context *blowfish_ctx=NULL;
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switch( cert->d.rsa.protect_algo ) {
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/* FIXME: use test variables to check for the correct key */
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case CIPHER_ALGO_NONE: BUG(); break;
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case CIPHER_ALGO_BLOWFISH:
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keyid_from_skc( cert, keyid );
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dek = get_passphrase_hash( keyid, NULL );
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blowfish_ctx = m_alloc_secure( sizeof *blowfish_ctx );
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blowfish_setkey( blowfish_ctx, dek->key, dek->keylen );
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m_free(dek); /* pw is in secure memory, so m_free() burns it */
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blowfish_setiv( blowfish_ctx, NULL );
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blowfish_decode_cfb( blowfish_ctx,
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cert->d.rsa.protect.blowfish.iv,
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cert->d.rsa.protect.blowfish.iv, 8 );
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csum = 0;
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#define X(a) do { \
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mpi_set_secure(cert->d.rsa.rsa_##a); \
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buffer = mpi_get_buffer( cert->d.rsa.rsa_##a, &nbytes, NULL );\
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csum += checksum_u16( nbytes*8 ); \
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blowfish_decode_cfb( blowfish_ctx, buffer, buffer, nbytes ); \
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csum += checksum( buffer, nbytes ); \
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mpi_set_buffer(cert->d.rsa.rsa_##a, buffer, nbytes, 0 ); \
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m_free( buffer ); \
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} while(0)
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X(d);
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X(p);
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X(q);
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X(u);
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#undef X
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cert->d.rsa.is_protected = 0;
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m_free( blowfish_ctx );
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/* now let's see wether we have used the right passphrase */
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if( csum != cert->d.rsa.csum )
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return G10ERR_BAD_PASS;
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skey.d = cert->d.rsa.rsa_d;
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skey.p = cert->d.rsa.rsa_p;
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skey.q = cert->d.rsa.rsa_q;
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skey.u = cert->d.rsa.rsa_u;
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res = rsa_check_secret_key( &skey );
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memset( &skey, 0, sizeof skey );
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if( !res )
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return G10ERR_BAD_PASS;
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break;
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default:
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return G10ERR_CIPHER_ALGO; /* unsupported protection algorithm */
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}
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}
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else { /* not protected */
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csum =0;
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buffer = mpi_get_buffer( cert->d.rsa.rsa_d, &nbytes, NULL );
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csum += checksum_u16( nbytes*8 );
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csum += checksum( buffer, nbytes );
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m_free( buffer );
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buffer = mpi_get_buffer( cert->d.rsa.rsa_p, &nbytes, NULL );
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csum += checksum_u16( nbytes*8 );
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csum += checksum( buffer, nbytes );
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m_free( buffer );
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buffer = mpi_get_buffer( cert->d.rsa.rsa_q, &nbytes, NULL );
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csum += checksum_u16( nbytes*8 );
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csum += checksum( buffer, nbytes );
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m_free( buffer );
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buffer = mpi_get_buffer( cert->d.rsa.rsa_u, &nbytes, NULL );
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csum += checksum_u16( nbytes*8 );
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csum += checksum( buffer, nbytes );
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m_free( buffer );
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if( csum != cert->d.rsa.csum )
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return G10ERR_CHECKSUM;
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}
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return 0;
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}
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#endif /*HAVE_RSA_CIPHER*/
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/****************
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* Check the secret key certificate
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* Ask up to 3 time for a correct passphrase
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*/
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int
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check_secret_key( PKT_secret_cert *cert )
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{
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int rc = G10ERR_BAD_PASS;
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int i;
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for(i=0; i < 3 && rc == G10ERR_BAD_PASS; i++ ) {
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if( i )
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log_error("Invalid passphrase; please try again ...\n");
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if( cert->pubkey_algo == PUBKEY_ALGO_ELGAMAL )
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rc = check_elg( cert );
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#ifdef HAVE_RSA_CIPHER
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else if( cert->pubkey_algo == PUBKEY_ALGO_RSA )
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rc = check_rsa( cert );
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#endif
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else
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rc = G10ERR_PUBKEY_ALGO;
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if( get_passphrase_fd() != -1 )
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break;
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}
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return rc;
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}
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/****************
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* check wether the secret key is protected.
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* Returns: 0 not protected, -1 on error or the protection algorithm
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*/
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int
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is_secret_key_protected( PKT_secret_cert *cert )
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{
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if( cert->pubkey_algo == PUBKEY_ALGO_ELGAMAL )
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return cert->d.elg.is_protected? cert->d.elg.protect.algo : 0;
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#ifdef HAVE_RSA_CIPHER
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else if( cert->pubkey_algo == PUBKEY_ALGO_RSA )
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return cert->d.rsa.is_protected? cert->d.rsa.protect_algo : 0;
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#endif
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else
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return -1; /* unsupported */
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}
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/****************
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* Protect the secret key certificate with the passphrase from DEK
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*/
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int
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protect_secret_key( PKT_secret_cert *cert, DEK *dek )
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{
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if( !dek )
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return 0;
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if( cert->pubkey_algo == PUBKEY_ALGO_ELGAMAL )
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return protect_elg( cert, dek );
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else
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return G10ERR_PUBKEY_ALGO;
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}
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