view rng_make_prng.c @ 211:f01f0400314d libtomcrypt

disapproval of revision 6a39eb8b36778460fca83b8149df2a8b6d3327fd
author Matt Johnston <matt@ucc.asn.au>
date Wed, 06 Jul 2005 13:23:45 +0000
parents d7da3b1e1540
children
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 *
 * Tom St Denis, [email protected], http://libtomcrypt.org
 */
/* portable way to get secure random bits to feed a PRNG */
#include "mycrypt.h"

int rng_make_prng(int bits, int wprng, prng_state *prng, 
                  void (*callback)(void))
{
   unsigned char buf[256];
   int err;
   
   _ARGCHK(prng != NULL);

   /* check parameter */
   if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
      return err;
   }

   if (bits < 64 || bits > 1024) {
      return CRYPT_INVALID_PRNGSIZE;
   }

   if ((err = prng_descriptor[wprng].start(prng)) != CRYPT_OK) {
      return err;
   }

   bits = ((bits/8)+((bits&7)!=0?1:0)) * 2;
   if (rng_get_bytes(buf, (unsigned long)bits, callback) != (unsigned long)bits) {
      return CRYPT_ERROR_READPRNG;
   }

   if ((err = prng_descriptor[wprng].add_entropy(buf, (unsigned long)bits, prng)) != CRYPT_OK) {
      return err;
   }

   if ((err = prng_descriptor[wprng].ready(prng)) != CRYPT_OK) {
      return err;
   }

   #ifdef CLEAN_STACK
      zeromem(buf, sizeof(buf));
   #endif
   return CRYPT_OK;
}