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/* seckey-cert.c - secret key certifucate packet handling
* Copyright (c) 1997 by Werner Koch (dd9jn)
*
* This file is part of G10.
*
* G10 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.
*
* G10 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 <assert.h>
#include "util.h"
#include "memory.h"
#include "packet.h"
#include "mpi.h"
#include "keydb.h"
#include "cipher.h"
static u16
checksum( byte *p )
{
u16 n, a;
n = *p++ << 8;
n |= *p++;
for(a=0; n; n-- )
a += *p++;
return a;
}
/****************
* Check the secret key certificate
*/
int
check_secret_key( PKT_seckey_cert *cert )
{
IDEA_context idea_ctx; /* FIXME: allocate this in secure space ! */
byte iv[8];
byte *mpibuf;
u16 n;
MPI temp_mpi;
int res;
u32 keyid[2];
#if IDEA_BLOCKSIZE != 8 || BLOWFISH_BLOCKSIZE != 8
#error unsupportted blocksize
#endif
if( cert->pubkey_algo != PUBKEY_ALGO_RSA )
return G10ERR_PUBKEY_ALGO; /* unsupport algorithm */
if( cert->d.rsa.is_protected ) { /* remove the protection */
DEK *dek = NULL;
BLOWFISH_context *blowfish_ctx=NULL;
switch( cert->d.rsa.protect_algo ) {
case CIPHER_ALGO_NONE:
log_bug("unprotect seckey_cert is flagged protected\n");
break;
case CIPHER_ALGO_IDEA:
case CIPHER_ALGO_BLOWFISH:
mpi_get_keyid( cert->d.rsa.rsa_n , keyid );
dek = get_passphrase_hash( keyid, NULL );
/* idea_setkey( &idea_ctx, dpw );*/
m_free(dek); /* pw is in secure memory, so m_free() burns it */
memset( iv, 0, BLOWFISH_BLOCKSIZE );
if( cert->d.rsa.protect_algo == CIPHER_ALGO_IDEA ) {
idea_setiv( &idea_ctx, iv );
/* fixme: is it save to leave the IV unencrypted in the
* certificate or should we move it to secure storage? */
idea_decode_cfb( &idea_ctx, cert->d.rsa.protect.idea.iv,
cert->d.rsa.protect.idea.iv, 8 );
}
else {
blowfish_ctx = m_alloc_secure( sizeof *blowfish_ctx );
blowfish_setiv( blowfish_ctx, iv );
blowfish_decode_cfb( blowfish_ctx,
cert->d.rsa.protect.blowfish.iv,
cert->d.rsa.protect.blowfish.iv, 8 );
}
cert->d.rsa.calc_csum = 0;
#define X(a) do { \
mpibuf = (byte*)cert->d.rsa.rsa_##a; \
n = ((mpibuf[0] << 8) | mpibuf[1])-2; \
if( blowfish_ctx ) \
blowfish_decode_cfb( blowfish_ctx, \
mpibuf+4, mpibuf+4, n ); \
else \
idea_decode_cfb( &idea_ctx, mpibuf+4, mpibuf+4, n );\
cert->d.rsa.calc_csum += checksum( mpibuf ); \
cert->d.rsa.rsa_##a = mpi_decode_buffer( mpibuf ); \
m_free( mpibuf ); \
} while(0)
X(d);
X(p);
X(q);
X(u);
#undef X
m_free( blowfish_ctx );
cert->d.rsa.is_protected = 0;
#if 0
#define X(a) do { printf("\tRSA " #a ": "); \
mpi_print(stdout, cert->d.rsa.rsa_##a, 1 ); \
putchar('\n'); \
} while(0)
X(n);
X(e);
X(d);
X(p);
X(q);
X(u);
#undef X
#endif
/* now let's see wether we have used the right passphrase */
if( cert->d.rsa.calc_csum != cert->d.rsa.csum )
return G10ERR_BAD_PASS;
temp_mpi = mpi_alloc(40);
mpi_mul(temp_mpi, cert->d.rsa.rsa_p, cert->d.rsa.rsa_q );
res = mpi_cmp( temp_mpi, cert->d.rsa.rsa_n );
mpi_free(temp_mpi);
if( res )
return G10ERR_BAD_PASS;
break;
default:
return G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */
}
}
/* must check the checksum here, because we didn't do it when
* parsing an unprotected certificate */
if( cert->d.rsa.calc_csum != cert->d.rsa.csum ) {
log_error("checksum in secret key certificate is wrong\n");
log_debug("stored csum=%04hx calculated csum=%04hx\n",
cert->d.rsa.csum, cert->d.rsa.calc_csum );
return G10ERR_CHECKSUM;
}
return 0;
}
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