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125 lines
3.0 KiB
C
125 lines
3.0 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 <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include "util.h"
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#include "cipher.h"
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struct cache {
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int len;
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byte buffer[100]; /* fixme: should be allocalted with m_alloc_secure()*/
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};
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static struct cache cache[3];
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#define MASK_LEVEL(a) do {if( a > 2 ) a = 2; else if( a < 0 ) a = 0; } while(0)
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static int open_device( const char *name, int minor );
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static void fill_buffer( byte *buffer, size_t length, int level );
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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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for( ; length; length-- )
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*buffer++ = get_random_byte(level);
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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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MASK_LEVEL(level);
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if( !cache[level].len ) {
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fill_buffer(cache[level].buffer, DIM(cache[level].buffer), level );
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cache[level].len = DIM(cache[level].buffer);
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}
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return cache[level].buffer[--cache[level].len];
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}
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static int
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open_device( const char *name, int minor )
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{
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int fd;
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struct stat sb;
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fd = open( name, O_RDONLY );
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if( fd == -1 )
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log_fatal("can't open %s: %s\n", name, strerror(errno) );
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if( fstat( fd, &sb ) )
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log_fatal("stat() off %s failed: %s\n", name, strerror(errno) );
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if( !S_ISCHR(sb.st_mode)
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#ifdef __linux__
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|| (sb.st_rdev >> 8) != 1
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|| (sb.st_rdev & 0xff) != minor
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#endif
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)
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log_fatal("invalid random device!\n" );
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return fd;
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}
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static void
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fill_buffer( byte *buffer, size_t length, int level )
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{
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FILE *fp;
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static int fd_urandom = -1;
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static int fd_random = -1;
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int fd;
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int n;
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if( level == 2 ) {
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if( fd_random == -1 )
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fd_random = open_device( "/dev/random", 8 );
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fd = fd_random;
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}
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else {
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if( fd_urandom == -1 )
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fd_urandom = open_device( "/dev/urandom", 9 );
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fd = fd_urandom;
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}
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do {
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do {
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n = read(fd, buffer, length );
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} while( n == -1 && errno == EINTR );
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if( n == -1 )
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log_fatal("read error on random device: %s\n", strerror(errno) );
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buffer += n;
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length -= n;
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} while( length );
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}
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