text: /* 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.
   */
  #include "tomcrypt.h"
  
  /**
     @file sprng.c
     Secure PRNG, Tom St Denis
  */
  
  /* A secure PRNG using the RNG functions.  Basically this is a
   * wrapper that allows you to use a secure RNG as a PRNG
   * in the various other functions.
   */
  
  #ifdef LTC_SPRNG
  
  const struct ltc_prng_descriptor sprng_desc =
  {
      "sprng", 0,
      &sprng_start,
      &sprng_add_entropy,
      &sprng_ready,
      &sprng_read,
      &sprng_done,
      &sprng_export,
      &sprng_import,
      &sprng_test
  };
  
  /**
    Start the PRNG
    @param prng     [out] The PRNG state to initialize
    @return CRYPT_OK if successful
  */
  int sprng_start(prng_state *prng)
  {
     LTC_UNUSED_PARAM(prng);
     return CRYPT_OK;
  }
  
  /**
    Add entropy to the PRNG state
    @param in       The data to add
    @param inlen    Length of the data to add
    @param prng     PRNG state to update
    @return CRYPT_OK if successful
  */
  int sprng_add_entropy(const unsigned char *in, unsigned long inlen, prng_state *prng)
  {
     LTC_UNUSED_PARAM(in);
     LTC_UNUSED_PARAM(inlen);
     LTC_UNUSED_PARAM(prng);
     return CRYPT_OK;
  }
  
  /**
    Make the PRNG ready to read from
    @param prng   The PRNG to make active
    @return CRYPT_OK if successful
  */
  int sprng_ready(prng_state *prng)
  {
     LTC_UNUSED_PARAM(prng);
     return CRYPT_OK;
  }
  
  /**
    Read from the PRNG
    @param out      Destination
    @param outlen   Length of output
    @param prng     The active PRNG to read from
    @return Number of octets read
  */
  unsigned long sprng_read(unsigned char *out, unsigned long outlen, prng_state *prng)
  {
     LTC_ARGCHK(out != NULL);
     LTC_UNUSED_PARAM(prng);
     return rng_get_bytes(out, outlen, NULL);
  }
  
  /**
    Terminate the PRNG
    @param prng   The PRNG to terminate
    @return CRYPT_OK if successful
  */
  int sprng_done(prng_state *prng)
  {
     LTC_UNUSED_PARAM(prng);
     return CRYPT_OK;
  }
  
  /**
    Export the PRNG state
    @param out       [out] Destination
    @param outlen    [in/out] Max size and resulting size of the state
    @param prng      The PRNG to export
    @return CRYPT_OK if successful
  */
  int sprng_export(unsigned char *out, unsigned long *outlen, prng_state *prng)
  {
     LTC_ARGCHK(outlen != NULL);
     LTC_UNUSED_PARAM(out);
     LTC_UNUSED_PARAM(prng);
  
     *outlen = 0;
     return CRYPT_OK;
  }
  
  /**
    Import a PRNG state
    @param in       The PRNG state
    @param inlen    Size of the state
    @param prng     The PRNG to import
    @return CRYPT_OK if successful
  */
  int sprng_import(const unsigned char *in, unsigned long inlen, prng_state *prng)
  {
    LTC_UNUSED_PARAM(in);
    LTC_UNUSED_PARAM(inlen);
    LTC_UNUSED_PARAM(prng);
     return CRYPT_OK;
  }
  
  /**
    PRNG self-test
    @return CRYPT_OK if successful, CRYPT_NOP if self-testing has been disabled
  */
  int sprng_test(void)
  {
  #ifndef LTC_TEST
     return CRYPT_NOP;
  #else
     prng_state st;
     unsigned char en[] = { 0x01, 0x02, 0x03, 0x04 };
     unsigned char out[1000];
     int err;
  
     if ((err = sprng_start(&st)) != CRYPT_OK)                         return err;
     if ((err = sprng_add_entropy(en, sizeof(en), &st)) != CRYPT_OK)   return err;
     if ((err = sprng_ready(&st)) != CRYPT_OK)                         return err;
     if (sprng_read(out, 500, &st) != 500)                             return CRYPT_ERROR_READPRNG; /* skip 500 bytes */
     if ((err = sprng_done(&st)) != CRYPT_OK)                          return err;
  
     return CRYPT_OK;
  #endif
  }
  
  #endif
  
  
  
  
  /* ref:         $Format:%D$ */
  /* git commit:  $Format:%H$ */
  /* commit time: $Format:%ai$ */
  