/* seckey-cert.c - secret key certifucate packet handling * 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 #include #include #include #include #include "util.h" #include "memory.h" #include "packet.h" #include "mpi.h" #include "keydb.h" #include "cipher.h" #include "main.h" #include "options.h" #include "i18n.h" static int do_check( PKT_secret_key *sk ) { byte *buffer; u16 csum=0; int i, res; unsigned nbytes; if( sk->is_protected ) { /* remove the protection */ DEK *dek = NULL; u32 keyid[2]; CIPHER_HANDLE cipher_hd=NULL; PKT_secret_key *save_sk; char save_iv[8]; if( sk->protect.algo == CIPHER_ALGO_NONE ) BUG(); if( check_cipher_algo( sk->protect.algo ) ) return G10ERR_CIPHER_ALGO; /* unsupported protection algorithm */ if( cipher_get_blocksize( sk->protect.algo ) != 8 ) return G10ERR_CIPHER_ALGO; /* unsupported protection algorithm */ keyid_from_sk( sk, keyid ); dek = passphrase_to_dek( keyid, sk->protect.algo, &sk->protect.s2k, 0 ); cipher_hd = cipher_open( sk->protect.algo, CIPHER_MODE_AUTO_CFB, 1); cipher_setkey( cipher_hd, dek->key, dek->keylen ); cipher_setiv( cipher_hd, NULL ); m_free(dek); save_sk = copy_secret_key( NULL, sk ); memcpy(save_iv, sk->protect.iv, 8 ); cipher_decrypt( cipher_hd, sk->protect.iv, sk->protect.iv, 8 ); csum = 0; if( sk->version >= 4 ) { int ndata; byte *p, *data; i = pubkey_get_npkey(sk->pubkey_algo); assert( mpi_is_opaque( sk->skey[i] ) ); p = mpi_get_opaque( sk->skey[i], &ndata ); data = m_alloc_secure( ndata ); cipher_decrypt( cipher_hd, data, p, ndata ); mpi_free( sk->skey[i] ); sk->skey[i] = NULL ; p = data; if( ndata < 2 ) { log_error("not enough bytes for checksum\n"); sk->csum = 0; csum = 1; } else { csum = checksum( data, ndata-2); sk->csum = data[ndata-2] << 8 | data[ndata-1]; } /* must check it here otherwise the mpi_read_xx would fail * because the length das an abritary value */ if( sk->csum == csum ) { for( ; i < pubkey_get_nskey(sk->pubkey_algo); i++ ) { nbytes = ndata; sk->skey[i] = mpi_read_from_buffer(p, &nbytes, 1 ); ndata -= nbytes; p += nbytes; } } m_free(data); } else { for(i=pubkey_get_npkey(sk->pubkey_algo); i < pubkey_get_nskey(sk->pubkey_algo); i++ ) { buffer = mpi_get_secure_buffer( sk->skey[i], &nbytes, NULL ); cipher_sync( cipher_hd ); assert( mpi_is_protected(sk->skey[i]) ); cipher_decrypt( cipher_hd, buffer, buffer, nbytes ); mpi_set_buffer( sk->skey[i], buffer, nbytes, 0 ); mpi_clear_protect_flag( sk->skey[i] ); csum += checksum_mpi( sk->skey[i] ); m_free( buffer ); } if( opt.emulate_bugs & EMUBUG_GPGCHKSUM ) { csum = sk->csum; } } cipher_close( cipher_hd ); /* now let's see whether we have used the right passphrase */ if( csum != sk->csum ) { copy_secret_key( sk, save_sk ); free_secret_key( save_sk ); memcpy( sk->protect.iv, save_iv, 8 ); return G10ERR_BAD_PASS; } /* the checksum may fail, so we also check the key itself */ res = pubkey_check_secret_key( sk->pubkey_algo, sk->skey ); if( res ) { copy_secret_key( sk, save_sk ); free_secret_key( save_sk ); memcpy( sk->protect.iv, save_iv, 8 ); return G10ERR_BAD_PASS; } free_secret_key( save_sk ); sk->is_protected = 0; } else { /* not protected, assume it is okay if the checksum is okay */ csum = 0; for(i=pubkey_get_npkey(sk->pubkey_algo); i < pubkey_get_nskey(sk->pubkey_algo); i++ ) { csum += checksum_mpi( sk->skey[i] ); } if( csum != sk->csum ) return G10ERR_CHECKSUM; } return 0; } /**************** * Check the secret key * Ask up to 3 times for a correct passphrase */ int check_secret_key( PKT_secret_key *sk ) { int rc = G10ERR_BAD_PASS; int i; for(i=0; i < 3 && rc == G10ERR_BAD_PASS; i++ ) { if( i ) log_error(_("Invalid passphrase; please try again ...\n")); rc = do_check( sk ); #if 0 /* set to 1 to enable the workaround */ if( rc == G10ERR_BAD_PASS && sk->is_protected && sk->protect.algo == CIPHER_ALGO_BLOWFISH && sk->pubkey_algo != PUBKEY_ALGO_ELGAMAL ) { /* Workaround for a bug in 0.2.16 which still used * a 160 bit key for BLOWFISH. */ log_info("trying workaround for 0.2.16 passphrase bug ...\n"); log_info("If you don't need this, uncomment it in g10/seckey-cert.c\n\n"); sk->protect.algo = CIPHER_ALGO_BLOWFISH160; rc = do_check( sk ); if( rc ) rc = G10ERR_BAD_PASS; sk->protect.algo = CIPHER_ALGO_BLOWFISH; } #endif if( get_passphrase_fd() != -1 ) break; } return rc; } /**************** * check whether the secret key is protected. * Returns: 0 not protected, -1 on error or the protection algorithm */ int is_secret_key_protected( PKT_secret_key *sk ) { return sk->is_protected? sk->protect.algo : 0; } /**************** * Protect the secret key with the passphrase from DEK */ int protect_secret_key( PKT_secret_key *sk, DEK *dek ) { int i,j, rc = 0; byte *buffer; unsigned nbytes; u16 csum; if( !dek ) return 0; if( !sk->is_protected ) { /* okay, apply the protection */ CIPHER_HANDLE cipher_hd=NULL; if( check_cipher_algo( sk->protect.algo ) ) rc = G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */ else if( cipher_get_blocksize( sk->protect.algo ) != 8 ) rc = G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */ else { cipher_hd = cipher_open( sk->protect.algo, CIPHER_MODE_AUTO_CFB, 1 ); cipher_setkey( cipher_hd, dek->key, dek->keylen ); cipher_setiv( cipher_hd, NULL ); cipher_encrypt( cipher_hd, sk->protect.iv, sk->protect.iv, 8 ); if( sk->version >= 4 ) { #define NMPIS (PUBKEY_MAX_NSKEY - PUBKEY_MAX_NPKEY) byte *buffer[NMPIS]; unsigned nbytes[NMPIS]; unsigned nbits[NMPIS]; int ndata=0; byte *p, *data; for(j=0, i = pubkey_get_npkey(sk->pubkey_algo); i < pubkey_get_nskey(sk->pubkey_algo); i++, j++ ) { assert( !mpi_is_opaque( sk->skey[i] ) ); buffer[j] = mpi_get_buffer( sk->skey[i], &nbytes[j], NULL ); nbits[j] = mpi_get_nbits( sk->skey[i] ); ndata += nbytes[j] + 2; } for( ; j < NMPIS; j++ ) buffer[j] = NULL; ndata += 2; /* for checksum */ data = m_alloc_secure( ndata ); p = data; for(j=0; j < NMPIS && buffer[j]; j++ ) { p[0] = nbits[j] >> 8 ; p[1] = nbits[j]; p += 2; memcpy(p, buffer[j], nbytes[j] ); p += nbytes[j]; m_free(buffer[j]); } #undef NMPIS csum = checksum( data, ndata-2); sk->csum = csum; *p++ = csum >> 8; *p++ = csum; assert( p == data+ndata ); cipher_encrypt( cipher_hd, data, data, ndata ); for(i = pubkey_get_npkey(sk->pubkey_algo); i < pubkey_get_nskey(sk->pubkey_algo); i++ ) { mpi_free( sk->skey[i] ); sk->skey[i] = NULL; } i = pubkey_get_npkey(sk->pubkey_algo); sk->skey[i] = mpi_set_opaque(NULL, data, ndata ); } else { /* NOTE: we always recalculate the checksum because there * are some test releases which calculated it wrong */ csum = 0; for(i=pubkey_get_npkey(sk->pubkey_algo); i < pubkey_get_nskey(sk->pubkey_algo); i++ ) { csum += checksum_mpi_counted_nbits( sk->skey[i] ); buffer = mpi_get_buffer( sk->skey[i], &nbytes, NULL ); cipher_sync( cipher_hd ); assert( !mpi_is_protected(sk->skey[i]) ); cipher_encrypt( cipher_hd, buffer, buffer, nbytes ); mpi_set_buffer( sk->skey[i], buffer, nbytes, 0 ); mpi_set_protect_flag( sk->skey[i] ); m_free( buffer ); } sk->csum = csum; } sk->is_protected = 1; cipher_close( cipher_hd ); } } return rc; }