* cryptographic random number generator for PuTTY's ssh client
*/
+#include "putty.h"
#include "ssh.h"
+#include <assert.h>
+
+/* Collect environmental noise every 5 minutes */
+#define NOISE_REGULAR_INTERVAL (5*60*TICKSPERSEC)
void noise_get_heavy(void (*func) (void *, int));
void noise_get_light(void (*func) (void *, int));
unsigned char incomingb[HASHINPUT];
int incomingpos;
+
+ int stir_pending;
};
static struct RandPool pool;
int random_active = 0;
+long next_noise_collection;
-void random_stir(void)
+static void random_stir(void)
{
word32 block[HASHINPUT / sizeof(word32)];
word32 digest[HASHSIZE / sizeof(word32)];
int i, j, k;
+ /*
+ * noise_get_light will call random_add_noise, which may call
+ * back to here. Prevent recursive stirs.
+ */
+ if (pool.stir_pending)
+ return;
+ pool.stir_pending = TRUE;
+
noise_get_light(random_add_noise);
SHATransform((word32 *) pool.incoming, (word32 *) pool.incomingb);
memcpy(pool.incoming, digest, sizeof(digest));
pool.poolpos = sizeof(pool.incoming);
+
+ pool.stir_pending = FALSE;
}
void random_add_noise(void *noise, int length)
pool.poolpos = i;
}
-void random_init(void)
+static void random_timer(void *ctx, long now)
+{
+ if (random_active > 0 && now - next_noise_collection >= 0) {
+ noise_regular();
+ next_noise_collection =
+ schedule_timer(NOISE_REGULAR_INTERVAL, random_timer, &pool);
+ }
+}
+
+void random_ref(void)
{
- memset(&pool, 0, sizeof(pool)); /* just to start with */
+ if (!random_active) {
+ memset(&pool, 0, sizeof(pool)); /* just to start with */
- random_active = 1;
+ noise_get_heavy(random_add_heavynoise_bitbybit);
+ random_stir();
- noise_get_heavy(random_add_heavynoise_bitbybit);
- random_stir();
+ next_noise_collection =
+ schedule_timer(NOISE_REGULAR_INTERVAL, random_timer, &pool);
+ }
+
+ random_active++;
+}
+
+void random_unref(void)
+{
+ random_active--;
+ assert(random_active >= 0);
+ if (random_active) return;
+
+ expire_timer_context(&pool);
}
int random_byte(void)
void random_get_savedata(void **data, int *len)
{
+ void *buf = snewn(POOLSIZE / 2, char);
random_stir();
- *data = pool.pool + pool.poolpos;
+ memcpy(buf, pool.pool + pool.poolpos, POOLSIZE / 2);
*len = POOLSIZE / 2;
+ *data = buf;
+ random_stir();
}