rng.cpp

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/*
* (C) 2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/rng.h>
#include <botan/entropy_src.h>
#include <botan/loadstor.h>
#include <botan/internal/os_utils.h>

#if defined(BOTAN_HAS_AUTO_SEEDING_RNG)
  #include <botan/auto_rng.h>
#endif

namespace Botan {

void RandomNumberGenerator::randomize_with_ts_input(uint8_t output[], size_t output_len)
   {
   if(this->accepts_input())
      {
      /*
      Form additional input which is provided to the PRNG implementation
      to paramaterize the KDF output.
      */
      uint8_t additional_input[16] = { 0 };
      store_le(OS::get_system_timestamp_ns(), additional_input);
      store_le(OS::get_high_resolution_clock(), additional_input + 8);

      this->randomize_with_input(output, output_len, additional_input, sizeof(additional_input));
      }
   else
      {
      this->randomize(output, output_len);
      }
   }

void RandomNumberGenerator::randomize_with_input(uint8_t output[], size_t output_len,
                                                 const uint8_t input[], size_t input_len)
   {
   this->add_entropy(input, input_len);
   this->randomize(output, output_len);
   }

size_t RandomNumberGenerator::reseed(Entropy_Sources& srcs,
                                     size_t poll_bits,
                                     std::chrono::milliseconds poll_timeout)
   {
   if(this->accepts_input())
      {
      return srcs.poll(*this, poll_bits, poll_timeout);
      }
   else
      {
      return 0;
      }
   }

void RandomNumberGenerator::reseed_from_rng(RandomNumberGenerator& rng, size_t poll_bits)
   {
   if(this->accepts_input())
      {
      secure_vector<uint8_t> buf(poll_bits / 8);
      rng.randomize(buf.data(), buf.size());
      this->add_entropy(buf.data(), buf.size());
      }
   }

RandomNumberGenerator* RandomNumberGenerator::make_rng()
   {
#if defined(BOTAN_HAS_AUTO_SEEDING_RNG)
   return new AutoSeeded_RNG;
#else
   throw Exception("make_rng failed, no AutoSeeded_RNG in this build");
#endif
   }

#if defined(BOTAN_TARGET_OS_HAS_THREADS)

#if defined(BOTAN_HAS_AUTO_SEEDING_RNG)
Serialized_RNG::Serialized_RNG() : m_rng(new AutoSeeded_RNG) {}
#else
Serialized_RNG::Serialized_RNG()
   {
   throw Exception("Serialized_RNG default constructor failed: AutoSeeded_RNG disabled in build");
   }
#endif

#endif

}