mirror of git://git.gnupg.org/gnupg.git
69 lines
1.9 KiB
C
69 lines
1.9 KiB
C
/* random.c - random number generator
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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 <errno.h>
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#include "util.h"
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#include "cipher.h"
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static struct {
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int level;
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int len;
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byte buffer[100]; /* fixme: should this be allocated in secure space? */
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} cache;
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/****************
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* Fill the buffer with LENGTH bytes of cryptologic strong
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* random bytes. level 0 is not very strong, 1 is strong enough
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* for most usage, 2 is good for key generation stuff but may be very slow.
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*/
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void
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randomize_buffer( byte *buffer, size_t length, int level )
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{
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FILE *fp;
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if( level == 2 )
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level = 1; /* 2 is much too slow */
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/* FIXME: do a stat and check that we have the correct device numbers*/
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fp = fopen(level < 2? "/dev/urandom":"/dev/random", "r");
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if( !fp )
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log_fatal("can't open random device: %s\n", strerror(errno) );
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for( ; length; length-- )
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*buffer++ = getc(fp);
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fclose(fp);
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}
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byte
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get_random_byte( int level )
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{
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if( !cache.len || cache.level < level ) {
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randomize_buffer(cache.buffer, DIM(cache.buffer), level );
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cache.level = level;
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cache.len = DIM(cache.buffer);
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}
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return cache.buffer[--cache.len];
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}
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