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/*
* Random Number Generator
* (C) 1999-2008,2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/rng.h>
#include <botan/hmac_drbg.h>
#include <botan/auto_rng.h>
#include <botan/entropy_src.h>
#include <botan/loadstor.h>
#include <botan/internal/os_utils.h>
#include <chrono>
namespace Botan {
size_t RandomNumberGenerator::reseed(size_t bits_to_collect)
{
return this->reseed_with_timeout(bits_to_collect,
BOTAN_RNG_RESEED_DEFAULT_TIMEOUT);
}
size_t RandomNumberGenerator::reseed_with_timeout(size_t bits_to_collect,
std::chrono::milliseconds timeout)
{
return this->reseed_with_sources(Entropy_Sources::global_sources(),
bits_to_collect,
timeout);
}
size_t RandomNumberGenerator::reseed_with_sources(Entropy_Sources& srcs,
size_t poll_bits,
std::chrono::milliseconds poll_timeout)
{
typedef std::chrono::system_clock clock;
auto deadline = clock::now() + poll_timeout;
double bits_collected = 0;
Entropy_Accumulator accum([&](const byte in[], size_t in_len, double entropy_estimate) {
add_entropy(in, in_len);
bits_collected += entropy_estimate;
return (bits_collected >= poll_bits || clock::now() > deadline);
});
srcs.poll(accum);
return bits_collected;
}
Stateful_RNG::Stateful_RNG(size_t bytes_before_reseed) :
m_max_bytes_before_reseed_required(bytes_before_reseed)
{
}
size_t Stateful_RNG::reseed_with_sources(Entropy_Sources& srcs,
size_t poll_bits,
std::chrono::milliseconds poll_timeout)
{
size_t bits_collected = RandomNumberGenerator::reseed_with_sources(srcs, poll_bits, poll_timeout);
if(bits_collected >= poll_bits)
{
m_successful_initialization = true;
m_bytes_since_reseed = 0;
}
return bits_collected;
}
void Stateful_RNG::reseed_check(size_t bytes_requested)
{
const bool fork_detected = (m_last_pid > 0) && (OS::get_process_id() != m_last_pid);
m_bytes_since_reseed += bytes_requested;
m_last_pid = OS::get_process_id();
if(!is_seeded() || fork_detected)
{
this->reseed(BOTAN_RNG_RESEED_POLL_BITS);
}
else if(m_max_bytes_before_reseed_required > 0 &&
m_bytes_since_reseed >= m_max_bytes_before_reseed_required)
{
this->reseed_with_timeout(BOTAN_RNG_AUTO_RESEED_POLL_BITS,
BOTAN_RNG_AUTO_RESEED_TIMEOUT);
}
if(!is_seeded())
{
throw PRNG_Unseeded(name());
}
}
void Stateful_RNG::initialize_with(const byte input[], size_t len)
{
add_entropy(input, len);
m_successful_initialization = true;
}
bool Stateful_RNG::is_seeded() const
{
return m_successful_initialization;
}
RandomNumberGenerator* RandomNumberGenerator::make_rng()
{
return new AutoSeeded_RNG;
}
AutoSeeded_RNG::AutoSeeded_RNG(size_t max_bytes_before_reseed)
{
m_rng.reset(new HMAC_DRBG("SHA-384", max_bytes_before_reseed));
size_t bits = m_rng->reseed(384);
if(!m_rng->is_seeded())
{
throw Exception("AutoSeeded_RNG failed to gather enough entropy only got " +
std::to_string(bits) + " bits");
}
}
void AutoSeeded_RNG::randomize(byte output[], size_t output_len)
{
/*
This data is not secret so skipping a vector/secure_vector allows
avoiding an allocation.
*/
typedef std::chrono::high_resolution_clock clock;
byte nonce_buf[16] = { 0 };
const uint32_t cur_ctr = m_counter++;
const uint32_t cur_pid = OS::get_process_id();
const uint64_t cur_time = clock::now().time_since_epoch().count();
store_le(cur_ctr, nonce_buf);
store_le(cur_pid, nonce_buf + 4);
store_le(cur_time, nonce_buf + 8);
m_rng->randomize_with_input(output, output_len,
nonce_buf, sizeof(nonce_buf));
++m_counter;
}
}
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