view ltc_prng.c @ 1663:c795520269f9

Fallback for key gen without hard link support (#89) Add a non-atomic fallback for key generation on platforms where link() is not permitted (such as most stock Android installs) or on filesystems without hard link support (such as FAT).
author Matt Robinson <git@nerdoftheherd.com>
date Sat, 14 Mar 2020 14:37:35 +0000
parents d68d61e7056a
children
line wrap: on
line source

/* Copied from libtomcrypt/src/prngs/sprng.c and modified to
 * use Dropbear's genrandom(). */

/* 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.com
 */
#include "includes.h"
#include "dbrandom.h"
#include "ltc_prng.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.
 */

#if DROPBEAR_LTC_PRNG

/**
  Start the PRNG
  @param prng     [out] The PRNG state to initialize
  @return CRYPT_OK if successful
*/  
int dropbear_prng_start(prng_state* UNUSED(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 dropbear_prng_add_entropy(const unsigned char* UNUSED(in), unsigned long UNUSED(inlen), prng_state* UNUSED(prng))
{
   return CRYPT_OK;
}

/**
  Make the PRNG ready to read from
  @param prng   The PRNG to make active
  @return CRYPT_OK if successful
*/  
int dropbear_prng_ready(prng_state* UNUSED(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 dropbear_prng_read(unsigned char* out, unsigned long outlen, prng_state* UNUSED(prng))
{
   LTC_ARGCHK(out != NULL);
   genrandom(out, outlen);
   return outlen;
}

/**
  Terminate the PRNG
  @param prng   The PRNG to terminate
  @return CRYPT_OK if successful
*/  
int dropbear_prng_done(prng_state* UNUSED(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 dropbear_prng_export(unsigned char* UNUSED(out), unsigned long* outlen, prng_state* UNUSED(prng))
{
   LTC_ARGCHK(outlen != NULL);

   *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 dropbear_prng_import(const unsigned char* UNUSED(in), unsigned long UNUSED(inlen), prng_state* UNUSED(prng))
{
   return CRYPT_OK;
}

/**
  PRNG self-test
  @return CRYPT_OK if successful, CRYPT_NOP if self-testing has been disabled
*/  
int dropbear_prng_test(void)
{
   return CRYPT_OK;
}

const struct ltc_prng_descriptor dropbear_prng_desc =
{
    "dropbear_prng", 0,
    dropbear_prng_start,
    dropbear_prng_add_entropy,
    dropbear_prng_ready,
    dropbear_prng_read,
    dropbear_prng_done,
    dropbear_prng_export,
    dropbear_prng_import,
    dropbear_prng_test
};


#endif /* DROPBEAR_LTC_PRNG */