/* 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 #include #include #include #include #include #include #include #include #include #ifdef HAVE_GETHRTIME #include #endif #ifdef HAVE_GETTIMEOFDAY #include #endif #ifdef HAVE_GETRUSAGE #include #endif #include "util.h" #include "rmd.h" #include "ttyio.h" #include "i18n.h" #include "random.h" #include "rand-internal.h" #include "dynload.h" #ifndef RAND_MAX /* for SunOS */ #define RAND_MAX 32767 #endif #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 #define BLOCKLEN 64 /* hash this amount of bytes */ #define DIGESTLEN 20 /* into a digest of this length (rmd160) */ /* poolblocks is the number of digests which make up the pool * and poolsize must be a multiple of the digest length * to make the AND operations faster, the size should also be * a multiple of ulong */ #define POOLBLOCKS 30 #define POOLSIZE (POOLBLOCKS*DIGESTLEN) #if (POOLSIZE % SIZEOF_UNSIGNED_LONG) #error Please make sure that poolsize is a multiple of ulong #endif #define POOLWORDS (POOLSIZE / SIZEOF_UNSIGNED_LONG) static int is_initialized; #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 int faked_rng; static void read_pool( byte *buffer, size_t length, int level ); static void add_randomness( const void *buffer, size_t length, int source ); static void random_poll(void); static void read_random_source( int requester, size_t length, int level); static int gather_faked( void (*add)(const void*, size_t, int), int requester, size_t length, int level ); static void initialize(void) { /* 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; cipher_modules_constructor(); } void secure_random_alloc() { secure_alloc = 1; } int quick_random_gen( int onoff ) { int last; read_random_source(0,0,0); /* init */ last = quick_test; if( onoff != -1 ) quick_test = onoff; return faked_rng? 1 : 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 ) { char *p = get_random_bits( length*8, level, m_is_secure(buffer) ); memcpy( buffer, p, length ); m_free(p); } int random_is_faked() { if( !is_initialized ) initialize(); return faked_rng || quick_test; } /**************** * Return a pointer to a randomized buffer of level 0 and LENGTH bits * caller must free the buffer. * Note: The returned value is rounded up to bytes. */ byte * get_random_bits( size_t nbits, int level, int secure ) { byte *buf, *p; size_t nbytes = (nbits+7)/8; if( quick_test && level > 1 ) level = 1; MASK_LEVEL(level); buf = secure && secure_alloc ? m_alloc_secure( nbytes ) : m_alloc( nbytes ); for( p = buf; nbytes > 0; ) { size_t n = nbytes > POOLSIZE? POOLSIZE : nbytes; read_pool( p, n, level ); nbytes -= n; p += n; } 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 */ /* for level 2 make sure that there is enough random in the pool */ if( level == 2 && pool_balance < length ) { size_t needed; if( pool_balance < 0 ) pool_balance = 0; needed = length - pool_balance; if( needed > POOLSIZE ) BUG(); read_random_source( 3, needed, 2 ); pool_balance += needed; } /* make sure the pool is filled */ while( !pool_filled ) random_poll(); /* do always a fast random poll */ fast_random_poll(); if( !level ) { /* no need for cryptographic strong random */ /* create a new pool */ for(i=0,dp=(ulong*)keypool, sp=(ulong*)rndpool; i < POOLWORDS; i++, dp++, sp++ ) *dp = *sp + ADD_VALUE; /* must mix both pools */ mix_pool(rndpool); mix_pool(keypool); memcpy( buffer, keypool, length ); } else { /* 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 randomness source. */ static 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; } } } static void random_poll() { read_random_source( 2, POOLSIZE/5, 1 ); } void fast_random_poll() { static void (*fnc)( void (*)(const void*, size_t, int), int) = NULL; static int initialized = 0; if( !initialized ) { if( !is_initialized ) initialize(); initialized = 1; fnc = dynload_getfnc_fast_random_poll(); } if( fnc ) { (*fnc)( add_randomness, 1 ); return; } /* fall back to the generic function */ #if HAVE_GETHRTIME { hrtime_t tv; tv = gethrtime(); add_randomness( &tv, sizeof(tv), 1 ); } #elif HAVE_GETTIMEOFDAY { struct timeval tv; if( gettimeofday( &tv, NULL ) ) BUG(); add_randomness( &tv.tv_sec, sizeof(tv.tv_sec), 1 ); add_randomness( &tv.tv_usec, sizeof(tv.tv_usec), 1 ); } #else /* use times */ { struct tms buf; times( &buf ); add_randomness( &buf, sizeof buf, 1 ); } #endif #ifdef HAVE_GETRUSAGE { struct rusage buf; if( getrusage( RUSAGE_SELF, &buf ) ) BUG(); add_randomness( &buf, sizeof buf, 1 ); memset( &buf, 0, sizeof buf ); } #endif } static void read_random_source( int requester, size_t length, int level ) { static int (*fnc)(void (*)(const void*, size_t, int), int, size_t, int) = NULL; if( !fnc ) { if( !is_initialized ) initialize(); fnc = dynload_getfnc_gather_random(); if( !fnc ) { faked_rng = 1; fnc = gather_faked; } if( !requester && !length && !level ) return; /* init only */ } if( (*fnc)( add_randomness, requester, length, level ) < 0 ) log_fatal("No way to gather entropy for the RNG\n"); } static int gather_faked( void (*add)(const void*, size_t, int), int requester, size_t length, int level ) { static int initialized=0; size_t n; char *buffer, *p; if( !initialized ) { log_info(_("WARNING: using insecure random number generator!!\n")); tty_printf(_("The random number generator is only a kludge to let\n" "it run - it is in no way a strong RNG!\n\n" "DON'T USE ANY DATA GENERATED BY THIS PROGRAM!!\n\n")); initialized=1; #ifdef HAVE_RAND srand(make_timestamp()*getpid()); #else srandom(make_timestamp()*getpid()); #endif } p = buffer = m_alloc( length ); n = length; #ifdef HAVE_RAND while( n-- ) *p++ = ((unsigned)(1 + (int) (256.0*rand()/(RAND_MAX+1.0)))-1); #else while( n-- ) *p++ = ((unsigned)(1 + (int) (256.0*random()/(RAND_MAX+1.0)))-1); #endif add_randomness( buffer, length, requester ); m_free(buffer); return 0; /* okay */ }