mirror of git://git.gnupg.org/gnupg.git
218 lines
6.0 KiB
C
218 lines
6.0 KiB
C
/* seckey-cert.c - secret key certifucate packet handling
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* Copyright (c) 1997 by Werner Koch (dd9jn)
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*
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* This file is part of G10.
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*
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* G10 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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* G10 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( byte *p )
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{
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u16 n, a;
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n = *p++ << 8;
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n |= *p++;
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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_seckey_cert *cert )
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{
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byte iv[8];
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byte *mpibuf;
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u16 n;
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MPI temp_mpi;
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int res;
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u32 keyid[2];
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ELG_secret_key skey;
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if( cert->d.elg.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.elg.protect_algo ) {
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case CIPHER_ALGO_NONE: log_bug(NULL); 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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m_free(dek); /* pw is in secure memory, so m_free() burns it */
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memset( iv, 0, BLOWFISH_BLOCKSIZE );
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blowfish_ctx = m_alloc_secure( sizeof *blowfish_ctx );
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blowfish_setiv( blowfish_ctx, iv );
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blowfish_decode_cfb( blowfish_ctx,
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cert->d.elg.protect.blowfish.iv,
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cert->d.elg.protect.blowfish.iv, 8 );
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cert->d.elg.calc_csum = 0;
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mpibuf = (byte*)cert->d.elg.x;
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n = ((mpibuf[0] << 8) | mpibuf[1])-2;
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blowfish_decode_cfb( blowfish_ctx, mpibuf+4, mpibuf+4, n );
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cert->d.elg.calc_csum += checksum( mpibuf );
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cert->d.elg.x = mpi_decode_buffer( mpibuf );
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m_free( mpibuf );
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m_free( blowfish_ctx );
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cert->d.elg.is_protected = 0;
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/* now let's see wether we have used the right passphrase */
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if( cert->d.elg.calc_csum != cert->d.elg.csum )
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return G10ERR_BAD_PASS;
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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 = cert->d.elg.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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return G10ERR_BAD_PASS;
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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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/* must check the checksum here, because we didn't do it when
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* parsing an unprotected certificate */
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if( cert->d.elg.calc_csum != cert->d.elg.csum ) {
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log_error("checksum in secret key certificate is wrong\n");
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log_debug("stored csum=%04hx calculated csum=%04hx\n",
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cert->d.elg.csum, cert->d.elg.calc_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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#ifdef HAVE_RSA_CIPHER
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static int
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check_rsa( PKT_seckey_cert *cert )
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{
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byte iv[8];
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byte *mpibuf;
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u16 n;
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MPI temp_mpi;
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int res;
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u32 keyid[2];
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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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case CIPHER_ALGO_NONE:
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log_bug("unprotect seckey_cert is flagged protected\n");
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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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m_free(dek); /* pw is in secure memory, so m_free() burns it */
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memset( iv, 0, BLOWFISH_BLOCKSIZE );
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blowfish_ctx = m_alloc_secure( sizeof *blowfish_ctx );
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blowfish_setiv( blowfish_ctx, iv );
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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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cert->d.rsa.calc_csum = 0;
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#define X(a) do { \
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mpibuf = (byte*)cert->d.rsa.rsa_##a; \
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n = ((mpibuf[0] << 8) | mpibuf[1])-2; \
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blowfish_decode_cfb( blowfish_ctx, \
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mpibuf+4, mpibuf+4, n ); \
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cert->d.rsa.calc_csum += checksum( mpibuf ); \
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cert->d.rsa.rsa_##a = mpi_decode_buffer( mpibuf ); \
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m_free( mpibuf ); \
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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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m_free( blowfish_ctx );
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cert->d.rsa.is_protected = 0;
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#if 0
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#define X(a) do { printf("\tRSA " #a ": "); \
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mpi_print(stdout, cert->d.rsa.rsa_##a, 1 ); \
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putchar('\n'); \
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} while(0)
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X(n); X(e); X(d); X(p); X(q); X(u);
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#undef X
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#endif
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/* now let's see wether we have used the right passphrase */
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if( cert->d.rsa.calc_csum != cert->d.rsa.csum )
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return G10ERR_BAD_PASS;
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temp_mpi = mpi_alloc(40);
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mpi_mul(temp_mpi, cert->d.rsa.rsa_p, cert->d.rsa.rsa_q );
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res = mpi_cmp( temp_mpi, cert->d.rsa.rsa_n );
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mpi_free(temp_mpi);
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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; /* unsupport protection algorithm */
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}
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}
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/* must check the checksum here, because we didn't do it when
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* parsing an unprotected certificate */
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if( cert->d.rsa.calc_csum != cert->d.rsa.csum ) {
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log_error("checksum in secret key certificate is wrong\n");
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log_debug("stored csum=%04hx calculated csum=%04hx\n",
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cert->d.rsa.csum, cert->d.rsa.calc_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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*/
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int
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check_secret_key( PKT_seckey_cert *cert )
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{
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if( cert->pubkey_algo == PUBKEY_ALGO_ELGAMAL )
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return 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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return check_rsa( cert );
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#endif
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else
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return G10ERR_PUBKEY_ALGO;
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}
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