crypto/openssh-3.8.1p1/openbsd-compat/bsd-arc4random.c

   1 /*
   2  * Copyright (c) 1999,2000,2004 Damien Miller <djm@mindrot.org>
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #include "includes.h"
  18 #include "log.h"
  19
  20 RCSID("$Id: bsd-arc4random.c,v 1.8 2004/02/17 05:49:55 djm Exp $");
  21
  22 #ifndef HAVE_ARC4RANDOM
  23
  24 #include <openssl/rand.h>
  25 #include <openssl/rc4.h>
  26 #include <openssl/err.h>
  27
  28 /* Size of key to use */
  29 #define SEED_SIZE 20
  30
  31 /* Number of bytes to reseed after */
  32 #define REKEY_BYTES     (1 << 24)
  33
  34 static int rc4_ready = 0;
  35 static RC4_KEY rc4;
  36
  37 unsigned int arc4random(void)
  38 {
  39         unsigned int r = 0;
  40         static int first_time = 1;
  41
  42         if (rc4_ready <= 0) {
  43                 if (first_time)
  44                         seed_rng();
  45                 first_time = 0;
  46                 arc4random_stir();
  47         }
  48
  49         RC4(&rc4, sizeof(r), (unsigned char *)&r, (unsigned char *)&r);
  50
  51         rc4_ready -= sizeof(r);
  52
  53         return(r);
  54 }
  55
  56 void arc4random_stir(void)
  57 {
  58         unsigned char rand_buf[SEED_SIZE];
  59
  60         memset(&rc4, 0, sizeof(rc4));
  61         if (RAND_bytes(rand_buf, sizeof(rand_buf)) <= 0)
  62                 fatal("Couldn't obtain random bytes (error %ld)",
  63                     ERR_get_error());
  64         RC4_set_key(&rc4, sizeof(rand_buf), rand_buf);
  65         RC4(&rc4, sizeof(rand_buf), rand_buf, rand_buf);
  66         memset(rand_buf, 0, sizeof(rand_buf));
  67
  68         rc4_ready = REKEY_BYTES;
  69 }
  70 #endif /* !HAVE_ARC4RANDOM */