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/*
* RandomNumberGenerator
* (C) 1999-2009 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_RANDOM_NUMBER_GENERATOR_H__
#define BOTAN_RANDOM_NUMBER_GENERATOR_H__
#include <botan/secmem.h>
#include <botan/exceptn.h>
#include <chrono>
#include <string>
#include <mutex>
namespace Botan {
class Entropy_Sources;
/**
* This class represents a random number (RNG) generator object.
*/
class BOTAN_DLL RandomNumberGenerator
{
public:
/**
* Create a seeded and active RNG object for general application use
* Added in 1.8.0
*/
static RandomNumberGenerator* make_rng();
/**
* Randomize a byte array.
* @param output the byte array to hold the random output.
* @param length the length of the byte array output.
*/
virtual void randomize(byte output[], size_t length) = 0;
/**
* Return a random vector
* @param bytes number of bytes in the result
* @return randomized vector of length bytes
*/
virtual secure_vector<byte> random_vec(size_t bytes)
{
secure_vector<byte> output(bytes);
randomize(output.data(), output.size());
return output;
}
/**
* Only usable with POD types, only useful with integers
* get_random<u64bit>()
*/
template<typename T> T get_random()
{
T r;
this->randomize(reinterpret_cast<byte*>(&r), sizeof(r));
return r;
}
/**
* Return a random byte
* @return random byte
*/
byte next_byte() { return get_random<byte>(); }
byte next_nonzero_byte()
{
byte b = next_byte();
while(b == 0)
b = next_byte();
return b;
}
/**
* Check whether this RNG is seeded.
* @return true if this RNG was already seeded, false otherwise.
*/
virtual bool is_seeded() const = 0;
/**
* Clear all internally held values of this RNG.
*/
virtual void clear() = 0;
/**
* Return the name of this object
*/
virtual std::string name() const = 0;
/**
* Seed this RNG using the global entropy sources and default timeout
* @param bits_to_collect is the number of bits of entropy to
attempt to gather from the entropy sources
*/
size_t reseed(size_t bits_to_collect);
/**
* Seed this RNG using the global entropy sources
* @param bits_to_collect is the number of bits of entropy to
attempt to gather from the entropy sources
* @param poll_timeout try not to run longer than this, no matter what
*/
size_t reseed_with_timeout(size_t bits_to_collect,
std::chrono::milliseconds poll_timeout);
/**
* Poll provided sources for up to poll_bits bits of entropy
* or until the timeout expires. Returns estimate of the number
* of bits collected.
*/
virtual size_t reseed_with_sources(Entropy_Sources& srcs,
size_t poll_bits,
std::chrono::milliseconds poll_timeout) = 0;
/**
* Add entropy to this RNG.
* @param in a byte array containg the entropy to be added
* @param length the length of the byte array in
*/
virtual void add_entropy(const byte in[], size_t length) = 0;
/*
* Never copy a RNG, create a new one
*/
RandomNumberGenerator(const RandomNumberGenerator& rng) = delete;
RandomNumberGenerator& operator=(const RandomNumberGenerator& rng) = delete;
RandomNumberGenerator() {}
virtual ~RandomNumberGenerator() {}
};
/**
* Null/stub RNG - fails if you try to use it for anything
*/
class BOTAN_DLL Null_RNG : public RandomNumberGenerator
{
public:
void randomize(byte[], size_t) override { throw PRNG_Unseeded("Null_RNG"); }
void clear() override {}
std::string name() const override { return "Null_RNG"; }
size_t reseed_with_sources(Entropy_Sources&, size_t,
std::chrono::milliseconds) override
{
return 0;
}
bool is_seeded() const override { return false; }
void add_entropy(const byte[], size_t) override {}
};
/**
* Wraps access to a RNG in a mutex
*/
class BOTAN_DLL Serialized_RNG : public RandomNumberGenerator
{
public:
void randomize(byte out[], size_t len) override
{
std::lock_guard<std::mutex> lock(m_mutex);
m_rng->randomize(out, len);
}
bool is_seeded() const override
{
std::lock_guard<std::mutex> lock(m_mutex);
return m_rng->is_seeded();
}
void clear() override
{
std::lock_guard<std::mutex> lock(m_mutex);
m_rng->clear();
}
std::string name() const override
{
std::lock_guard<std::mutex> lock(m_mutex);
return m_rng->name();
}
size_t reseed_with_sources(Entropy_Sources& src,
size_t bits,
std::chrono::milliseconds msec) override
{
std::lock_guard<std::mutex> lock(m_mutex);
return m_rng->reseed_with_sources(src, bits, msec);
}
void add_entropy(const byte in[], size_t len) override
{
std::lock_guard<std::mutex> lock(m_mutex);
m_rng->add_entropy(in, len);
}
Serialized_RNG() : m_rng(RandomNumberGenerator::make_rng()) {}
Serialized_RNG(RandomNumberGenerator* rng) : m_rng(rng) {}
private:
mutable std::mutex m_mutex;
std::unique_ptr<RandomNumberGenerator> m_rng;
};
}
#endif
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