Fortuna fixes. Marko Kreen

This commit is contained in:
Tom Lane 2005-07-18 17:12:54 +00:00
parent 2787db9b1d
commit 35c675a7fd
5 changed files with 194 additions and 89 deletions

View File

@ -26,7 +26,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $PostgreSQL: pgsql/contrib/pgcrypto/fortuna.c,v 1.3 2005/07/18 17:09:01 tgl Exp $
* $PostgreSQL: pgsql/contrib/pgcrypto/fortuna.c,v 1.4 2005/07/18 17:12:54 tgl Exp $
*/
#include "postgres.h"
@ -94,14 +94,16 @@
/* for one big request, reseed after this many bytes */
#define RESEED_BYTES (1024*1024)
/*
* Skip reseed if pool 0 has less than this many
* bytes added since last reseed.
*/
#define POOL0_FILL (256/8)
/*
* Algorithm constants
*/
/* max sources */
#define MAX_SOURCES 8
/* Both cipher key size and hash result size */
#define BLOCK 32
@ -118,9 +120,11 @@ struct fortuna_state {
uint8 key[BLOCK];
MD_CTX pool[NUM_POOLS];
CIPH_CTX ciph;
unsigned source_pos[MAX_SOURCES];
unsigned reseed_count;
struct timeval last_reseed_time;
unsigned pool0_bytes;
unsigned rnd_pos;
int counter_init;
};
typedef struct fortuna_state FState;
@ -161,7 +165,6 @@ static void md_result(MD_CTX *ctx, uint8 *dst)
memset(&tmp, 0, sizeof(tmp));
}
/*
* initialize state
*/
@ -173,6 +176,32 @@ static void init_state(FState *st)
md_init(&st->pool[i]);
}
/*
* Endianess does not matter.
* It just needs to change without repeating.
*/
static void inc_counter(FState *st)
{
uint32 *val = (uint32*)st->counter;
if (++val[0])
return;
if (++val[1])
return;
if (++val[2])
return;
++val[3];
}
/*
* This is called 'cipher in counter mode'.
*/
static void encrypt_counter(FState *st, uint8 *dst)
{
ciph_encrypt(&st->ciph, st->counter, dst);
inc_counter(st);
}
/*
* The time between reseed must be at least RESEED_INTERVAL
* microseconds.
@ -207,9 +236,8 @@ static void reseed(FState *st)
MD_CTX key_md;
uint8 buf[BLOCK];
/* check frequency */
if (too_often(st))
return;
/* set pool as empty */
st->pool0_bytes = 0;
/*
* Both #0 and #1 reseed would use only pool 0.
@ -243,50 +271,81 @@ static void reseed(FState *st)
memset(buf, 0, BLOCK);
}
/*
* Pick a random pool. This uses key bytes as random source.
*/
static unsigned get_rand_pool(FState *st)
{
unsigned rnd;
/*
* This slightly prefers lower pools - thats OK.
*/
rnd = st->key[st->rnd_pos] % NUM_POOLS;
st->rnd_pos++;
if (st->rnd_pos >= BLOCK)
st->rnd_pos = 0;
return rnd;
}
/*
* update pools
*/
static void add_entropy(FState *st, unsigned src_id, const uint8 *data, unsigned len)
static void add_entropy(FState *st, const uint8 *data, unsigned len)
{
unsigned pos;
uint8 hash[BLOCK];
MD_CTX md;
/* just in case there's a bug somewhere */
if (src_id >= MAX_SOURCES)
src_id = USER_ENTROPY;
/* hash given data */
md_init(&md);
md_update(&md, data, len);
md_result(&md, hash);
/* update pools round-robin manner */
pos = st->source_pos[src_id];
/*
* Make sure the pool 0 is initialized,
* then update randomly.
*/
if (st->reseed_count == 0 && st->pool0_bytes < POOL0_FILL)
pos = 0;
else
pos = get_rand_pool(st);
md_update( &st->pool[pos], hash, BLOCK);
if (++pos >= NUM_POOLS)
pos = 0;
st->source_pos[src_id] = pos;
if (pos == 0)
st->pool0_bytes += len;
memset(hash, 0, BLOCK);
memset(&md, 0, sizeof(md));
}
/*
* Endianess does not matter.
* It just needs to change without repeating.
* Just take 2 next blocks as new key
*/
static void inc_counter(FState *st)
static void rekey(FState *st)
{
uint32 *val = (uint32*)st->counter;
if (++val[0])
return;
if (++val[1])
return;
if (++val[2])
return;
++val[3];
encrypt_counter(st, st->key);
encrypt_counter(st, st->key + CIPH_BLOCK);
ciph_init(&st->ciph, st->key, BLOCK);
}
/*
* Fortuna relies on AES standing known-plaintext attack.
* In case it does not, slow down the attacker by initialising
* the couter to random value.
*/
static void init_counter(FState *st)
{
/* Use next block as counter. */
encrypt_counter(st, st->counter);
/* Hide the key. */
rekey(st);
/* The counter can be shuffled only once. */
st->counter_init = 1;
}
static void extract_data(FState *st, unsigned count, uint8 *dst)
@ -294,31 +353,17 @@ static void extract_data(FState *st, unsigned count, uint8 *dst)
unsigned n;
unsigned block_nr = 0;
/*
* Every request should be with different key,
* if possible.
*/
reseed(st);
/* Can we reseed? */
if (st->pool0_bytes >= POOL0_FILL && !too_often(st))
reseed(st);
/*
* If the reseed didn't happen, don't use the old data
* rather encrypt again.
*/
/* Is counter initialized? */
if (!st->counter_init)
init_counter(st);
while (count > 0) {
/* must not give out too many bytes with one key */
if (block_nr > (RESEED_BYTES / CIPH_BLOCK))
{
reseed(st);
block_nr = 0;
}
/* produce bytes */
ciph_encrypt(&st->ciph, st->counter, st->result);
block_nr++;
/* prepare for next time */
inc_counter(st);
encrypt_counter(st, st->result);
/* copy result */
if (count > CIPH_BLOCK)
@ -328,7 +373,17 @@ static void extract_data(FState *st, unsigned count, uint8 *dst)
memcpy(dst, st->result, n);
dst += n;
count -= n;
/* must not give out too many bytes with one key */
block_nr++;
if (block_nr > (RESEED_BYTES / CIPH_BLOCK))
{
rekey(st);
block_nr = 0;
}
}
/* Set new key for next request. */
rekey(st);
}
/*
@ -338,7 +393,7 @@ static void extract_data(FState *st, unsigned count, uint8 *dst)
static FState main_state;
static int init_done = 0;
void fortuna_add_entropy(unsigned src_id, const uint8 *data, unsigned len)
void fortuna_add_entropy(const uint8 *data, unsigned len)
{
if (!init_done)
{
@ -347,7 +402,7 @@ void fortuna_add_entropy(unsigned src_id, const uint8 *data, unsigned len)
}
if (!data || !len)
return;
add_entropy(&main_state, src_id, data, len);
add_entropy(&main_state, data, len);
}
void fortuna_get_bytes(unsigned len, uint8 *dst)

View File

@ -26,20 +26,14 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $PostgreSQL: pgsql/contrib/pgcrypto/fortuna.h,v 1.1 2005/07/10 13:46:28 momjian Exp $
* $PostgreSQL: pgsql/contrib/pgcrypto/fortuna.h,v 1.2 2005/07/18 17:12:54 tgl Exp $
*/
#ifndef __FORTUNA_H
#define __FORTUNA_H
/*
* Event source ID's
*/
#define SYSTEM_ENTROPY 0
#define USER_ENTROPY 1
void fortuna_get_bytes(unsigned len, uint8 *dst);
void fortuna_add_entropy(unsigned src_id, const uint8 *data, unsigned len);
void fortuna_add_entropy(const uint8 *data, unsigned len);
#endif

View File

@ -26,7 +26,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $PostgreSQL: pgsql/contrib/pgcrypto/internal.c,v 1.21 2005/07/18 17:09:01 tgl Exp $
* $PostgreSQL: pgsql/contrib/pgcrypto/internal.c,v 1.22 2005/07/18 17:12:54 tgl Exp $
*/
#include "postgres.h"
@ -42,9 +42,22 @@
#include "fortuna.h"
/*
* How often to try to acquire system entropy. (In seconds)
* System reseeds should be separated at least this much.
*/
#define SYSTEM_RESEED_FREQ (3*60*60)
#define SYSTEM_RESEED_MIN (20*60) /* 20 min */
/*
* How often to roll dice.
*/
#define SYSTEM_RESEED_CHECK_TIME (10*60) /* 10 min */
/*
* The chance is x/256 that the reseed happens.
*/
#define SYSTEM_RESEED_CHANCE (4) /* 256/4 * 10min ~ 10h */
/*
* If this much time has passed, force reseed.
*/
#define SYSTEM_RESEED_MAX (12*60*60) /* 12h */
#ifndef MD5_DIGEST_LENGTH
@ -823,20 +836,40 @@ px_get_pseudo_random_bytes(uint8 *dst, unsigned count)
}
static time_t seed_time = 0;
static time_t check_time = 0;
static void system_reseed(void)
{
uint8 buf[1024];
int n;
time_t t;
int skip = 1;
t = time(NULL);
if (seed_time && (t - seed_time) < SYSTEM_RESEED_FREQ)
if (seed_time == 0)
skip = 0;
else if ((t - seed_time) < SYSTEM_RESEED_MIN)
skip = 1;
else if ((t - seed_time) > SYSTEM_RESEED_MAX)
skip = 0;
else if (!check_time || (t - check_time) > SYSTEM_RESEED_CHECK_TIME)
{
check_time = t;
/* roll dice */
px_get_random_bytes(buf, 1);
skip = buf[0] >= SYSTEM_RESEED_CHANCE;
}
/* clear 1 byte */
memset(buf, 0, sizeof(buf));
if (skip)
return;
n = px_acquire_system_randomness(buf);
if (n > 0)
fortuna_add_entropy(SYSTEM_ENTROPY, buf, n);
fortuna_add_entropy(buf, n);
seed_time = t;
memset(buf, 0, sizeof(buf));
@ -854,7 +887,7 @@ int
px_add_entropy(const uint8 *data, unsigned count)
{
system_reseed();
fortuna_add_entropy(USER_ENTROPY, data, count);
fortuna_add_entropy(data, count);
return 0;
}

View File

@ -26,7 +26,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $PostgreSQL: pgsql/contrib/pgcrypto/pgp-pgsql.c,v 1.2 2005/07/11 15:07:59 tgl Exp $
* $PostgreSQL: pgsql/contrib/pgcrypto/pgp-pgsql.c,v 1.3 2005/07/18 17:12:54 tgl Exp $
*/
#include "postgres.h"
@ -86,6 +86,22 @@ PG_FUNCTION_INFO_V1(pg_dearmor);
} \
} while (0)
/*
* Mix a block of data into RNG.
*/
static void add_block_entropy(PX_MD *md, text *data)
{
uint8 sha1[20];
px_md_reset(md);
px_md_update(md, VARDATA(data), VARSIZE(data) - VARHDRSZ);
px_md_finish(md, sha1);
px_add_entropy(sha1, 20);
memset(sha1, 0, 20);
}
/*
* Mix user data into RNG. It is for user own interests to have
* RNG state shuffled.
@ -93,31 +109,38 @@ PG_FUNCTION_INFO_V1(pg_dearmor);
static void add_entropy(text *data1, text *data2, text *data3)
{
PX_MD *md;
uint8 sha1[20];
int res;
uint8 rnd[3];
if (!data1 && !data2 && !data3)
return;
res = px_find_digest("sha1", &md);
if (res < 0)
if (px_get_random_bytes(rnd, 3) < 0)
return;
if (data1)
px_md_update(md, VARDATA(data1), VARSIZE(data1) - VARHDRSZ);
if (data2)
px_md_update(md, VARDATA(data2), VARSIZE(data2) - VARHDRSZ);
if (data3)
px_md_update(md, VARDATA(data3), VARSIZE(data3) - VARHDRSZ);
if (px_find_digest("sha1", &md) < 0)
return;
/*
* Try to make the feeding unpredictable.
*
* Prefer data over keys, as it's rather likely
* that key is same in several calls.
*/
/* chance: 7/8 */
if (data1 && rnd[0] >= 32)
add_block_entropy(md, data1);
/* chance: 5/8 */
if (data2 && rnd[1] >= 160)
add_block_entropy(md, data2);
/* chance: 5/8 */
if (data3 && rnd[2] >= 160)
add_block_entropy(md, data3);
px_md_finish(md, sha1);
px_md_free(md);
res = px_add_entropy(sha1, 20);
memset(sha1, 0, 20);
if (res < 0)
ereport(NOTICE, (errmsg("add_entropy: %s", px_strerror(res))));
memset(rnd, 0, sizeof(rnd));
}
/*

View File

@ -26,7 +26,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $PostgreSQL: pgsql/contrib/pgcrypto/pgp-s2k.c,v 1.2 2005/07/11 15:07:59 tgl Exp $
* $PostgreSQL: pgsql/contrib/pgcrypto/pgp-s2k.c,v 1.3 2005/07/18 17:12:54 tgl Exp $
*/
#include "postgres.h"
@ -225,13 +225,13 @@ pgp_s2k_fill(PGP_S2K *s2k, int mode,int digest_algo)
case 0:
break;
case 1:
res = px_get_random_bytes(s2k->salt, PGP_S2K_SALT);
res = px_get_pseudo_random_bytes(s2k->salt, PGP_S2K_SALT);
break;
case 3:
res = px_get_random_bytes(s2k->salt, PGP_S2K_SALT);
res = px_get_pseudo_random_bytes(s2k->salt, PGP_S2K_SALT);
if (res < 0)
break;
res = px_get_random_bytes(&tmp, 1);
res = px_get_pseudo_random_bytes(&tmp, 1);
if (res < 0)
break;
s2k->iter = decide_count(tmp);