mirror of git://git.gnupg.org/gnupg.git
292 lines
6.8 KiB
C
292 lines
6.8 KiB
C
/* random.c - random number generator
|
|
* 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
|
|
*/
|
|
|
|
|
|
/****************
|
|
* This random number generator is modelled after the one described
|
|
* in Peter Gutmann's Paper: "Software Generation of Practically
|
|
* Strong Random Numbers".
|
|
*/
|
|
|
|
|
|
#include <config.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <assert.h>
|
|
#include <errno.h>
|
|
#include <string.h>
|
|
#include "util.h"
|
|
#include "rmd.h"
|
|
#include "ttyio.h"
|
|
#include "i18n.h"
|
|
#include "rand-internal.h"
|
|
|
|
|
|
#if SIZEOF_UNSIGNED_LONG == 8
|
|
#define ADD_VALUE 0xa5a5a5a5a5a5a5a5
|
|
#elif SIZEOF_UNSIGNED_LONG == 4
|
|
#define ADD_VALUE 0xa5a5a5a5
|
|
#else
|
|
#error weird size for an unsigned long
|
|
#endif
|
|
|
|
struct cache {
|
|
int len;
|
|
int size;
|
|
byte *buffer;
|
|
};
|
|
|
|
|
|
static int is_initialized;
|
|
static struct cache cache[3];
|
|
#define MASK_LEVEL(a) do {if( a > 2 ) a = 2; else if( a < 0 ) a = 0; } while(0)
|
|
static char *rndpool; /* allocated size is POOLSIZE+BLOCKLEN */
|
|
static char *keypool; /* allocated size is POOLSIZE+BLOCKLEN */
|
|
static size_t pool_readpos;
|
|
static size_t pool_writepos;
|
|
static int pool_filled;
|
|
static int pool_balance;
|
|
static int just_mixed;
|
|
|
|
static int secure_alloc;
|
|
static int quick_test;
|
|
|
|
|
|
static void read_pool( byte *buffer, size_t length, int level );
|
|
|
|
|
|
static void
|
|
initialize()
|
|
{
|
|
/* The data buffer is allocated somewhat larger, so that
|
|
* we can use this extra space (which is allocated in secure memory)
|
|
* as a temporary hash buffer */
|
|
rndpool = secure_alloc ? m_alloc_secure_clear(POOLSIZE+BLOCKLEN)
|
|
: m_alloc_clear(POOLSIZE+BLOCKLEN);
|
|
keypool = secure_alloc ? m_alloc_secure_clear(POOLSIZE+BLOCKLEN)
|
|
: m_alloc_clear(POOLSIZE+BLOCKLEN);
|
|
is_initialized = 1;
|
|
}
|
|
|
|
void
|
|
secure_random_alloc()
|
|
{
|
|
secure_alloc = 1;
|
|
}
|
|
|
|
|
|
int
|
|
quick_random_gen( int onoff )
|
|
{
|
|
int last = quick_test;
|
|
if( onoff != -1 )
|
|
quick_test = onoff;
|
|
#ifdef USE_RAND_DUMMY
|
|
last = 1; /* insecure RNG */
|
|
#endif
|
|
return last;
|
|
}
|
|
|
|
|
|
/****************
|
|
* Fill the buffer with LENGTH bytes of cryptographically strong
|
|
* random bytes. level 0 is not very strong, 1 is strong enough
|
|
* for most usage, 2 is good for key generation stuff but may be very slow.
|
|
*/
|
|
void
|
|
randomize_buffer( byte *buffer, size_t length, int level )
|
|
{
|
|
for( ; length; length-- )
|
|
*buffer++ = get_random_byte(level);
|
|
}
|
|
|
|
|
|
byte
|
|
get_random_byte( int level )
|
|
{
|
|
MASK_LEVEL(level);
|
|
if( !cache[level].len ) {
|
|
if( !is_initialized )
|
|
initialize();
|
|
if( !cache[level].buffer ) {
|
|
cache[level].size = 100;
|
|
cache[level].buffer = level && secure_alloc?
|
|
m_alloc_secure( cache[level].size )
|
|
: m_alloc( cache[level].size );
|
|
}
|
|
read_pool(cache[level].buffer, cache[level].size, level );
|
|
cache[level].len = cache[level].size;
|
|
}
|
|
|
|
return cache[level].buffer[--cache[level].len];
|
|
}
|
|
|
|
|
|
|
|
/****************
|
|
* Return a pointer to a randomized buffer of level 0 and LENGTH bits
|
|
* caller must free the buffer. This function does not use the
|
|
* cache (will be removed in future). Note: The returned value is
|
|
* rounded up to bytes.
|
|
*/
|
|
byte *
|
|
get_random_bits( size_t nbits, int level, int secure )
|
|
{
|
|
byte *buf;
|
|
size_t nbytes = (nbits+7)/8;
|
|
|
|
MASK_LEVEL(level);
|
|
buf = secure? m_alloc_secure( nbytes ) : m_alloc( nbytes );
|
|
read_pool( buf, nbytes, level );
|
|
return buf;
|
|
}
|
|
|
|
|
|
/****************
|
|
* Mix the pool
|
|
*/
|
|
static void
|
|
mix_pool(byte *pool)
|
|
{
|
|
char *hashbuf = pool + POOLSIZE;
|
|
char *p, *pend;
|
|
int i, n;
|
|
RMD160_CONTEXT md;
|
|
|
|
rmd160_init( &md );
|
|
#if DIGESTLEN != 20
|
|
#error must have a digest length of 20 for ripe-md-160
|
|
#endif
|
|
/* loop over the pool */
|
|
pend = pool + POOLSIZE;
|
|
memcpy(hashbuf, pend - DIGESTLEN, DIGESTLEN );
|
|
memcpy(hashbuf+DIGESTLEN, pool, BLOCKLEN-DIGESTLEN);
|
|
rmd160_mixblock( &md, hashbuf);
|
|
memcpy(pool, hashbuf, 20 );
|
|
|
|
p = pool;
|
|
for( n=1; n < POOLBLOCKS; n++ ) {
|
|
memcpy(hashbuf, p, DIGESTLEN );
|
|
|
|
p += DIGESTLEN;
|
|
if( p+DIGESTLEN+BLOCKLEN < pend )
|
|
memcpy(hashbuf+DIGESTLEN, p+DIGESTLEN, BLOCKLEN-DIGESTLEN);
|
|
else {
|
|
char *pp = p+DIGESTLEN;
|
|
for(i=DIGESTLEN; i < BLOCKLEN; i++ ) {
|
|
if( pp >= pend )
|
|
pp = pool;
|
|
hashbuf[i] = *pp++;
|
|
}
|
|
}
|
|
|
|
rmd160_mixblock( &md, hashbuf);
|
|
memcpy(p, hashbuf, 20 );
|
|
}
|
|
}
|
|
|
|
|
|
static void
|
|
read_pool( byte *buffer, size_t length, int level )
|
|
{
|
|
int i;
|
|
ulong *sp, *dp;
|
|
|
|
if( length >= POOLSIZE )
|
|
BUG(); /* not allowed */
|
|
if( !level ) { /* read simple random bytes */
|
|
read_random_source( buffer, length, level );
|
|
return;
|
|
}
|
|
|
|
/* for level 2 make sure that there is enough random in the pool */
|
|
if( level == 2 && pool_balance < length ) {
|
|
size_t needed;
|
|
byte *p;
|
|
|
|
if( pool_balance < 0 )
|
|
pool_balance = 0;
|
|
needed = length - pool_balance;
|
|
if( needed > POOLSIZE )
|
|
BUG();
|
|
p = m_alloc_secure( needed );
|
|
read_random_source( p, needed, 2 ); /* read /dev/random */
|
|
add_randomness( p, needed, 3);
|
|
m_free(p);
|
|
pool_balance += needed;
|
|
}
|
|
|
|
/* make sure the pool is filled */
|
|
while( !pool_filled )
|
|
random_poll();
|
|
/* do always a fast random poll */
|
|
fast_random_poll();
|
|
|
|
/* mix the pool (if add_randomness() didn't it) */
|
|
if( !just_mixed )
|
|
mix_pool(rndpool);
|
|
|
|
/* create a new pool */
|
|
for(i=0,dp=(ulong*)keypool, sp=(ulong*)rndpool;
|
|
i < POOLWORDS; i++, dp++, sp++ )
|
|
*dp = *sp + ADD_VALUE;
|
|
/* and mix both pools */
|
|
mix_pool(rndpool);
|
|
mix_pool(keypool);
|
|
/* read the required data
|
|
* we use a readpoiter to read from a different postion each
|
|
* time */
|
|
while( length-- ) {
|
|
*buffer++ = keypool[pool_readpos++];
|
|
if( pool_readpos >= POOLSIZE )
|
|
pool_readpos = 0;
|
|
pool_balance--;
|
|
}
|
|
if( pool_balance < 0 )
|
|
pool_balance = 0;
|
|
/* and clear the keypool */
|
|
memset( keypool, 0, POOLSIZE );
|
|
}
|
|
|
|
|
|
/****************
|
|
* Add LENGTH bytes of randomness from buffer to the pool.
|
|
* source may be used to specify the randomeness source.
|
|
*/
|
|
void
|
|
add_randomness( const void *buffer, size_t length, int source )
|
|
{
|
|
if( !is_initialized )
|
|
initialize();
|
|
while( length-- ) {
|
|
rndpool[pool_writepos++] = *((byte*)buffer)++;
|
|
if( pool_writepos >= POOLSIZE ) {
|
|
if( source > 1 )
|
|
pool_filled = 1;
|
|
pool_writepos = 0;
|
|
mix_pool(rndpool);
|
|
just_mixed = !length;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
|