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/*
* EntropySource
* (C) 2008,2009,2014,2015,2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_ENTROPY_H_
#define BOTAN_ENTROPY_H_
#include <botan/secmem.h>
#include <botan/rng.h>
#include <string>
#include <chrono>
#include <memory>
#include <vector>
namespace Botan {
class RandomNumberGenerator;
/**
* Abstract interface to a source of entropy
*/
class BOTAN_PUBLIC_API(2,0) Entropy_Source
{
public:
/**
* Return a new entropy source of a particular type, or null
* Each entropy source may require substantial resources (eg, a file handle
* or socket instance), so try to share them among multiple RNGs, or just
* use the preconfigured global list accessed by Entropy_Sources::global_sources()
*/
static std::unique_ptr<Entropy_Source> create(const std::string& type);
/**
* @return name identifying this entropy source
*/
virtual std::string name() const = 0;
/**
* Perform an entropy gathering poll
* @param rng will be provided with entropy via calls to add_entropy
* @return conservative estimate of actual entropy added to rng during poll
*/
virtual size_t poll(RandomNumberGenerator& rng) = 0;
virtual ~Entropy_Source() {}
};
class BOTAN_PUBLIC_API(2,0) Entropy_Sources final
{
public:
static Entropy_Sources& global_sources();
void add_source(std::unique_ptr<Entropy_Source> src);
std::vector<std::string> enabled_sources() const;
size_t poll(RandomNumberGenerator& rng,
size_t bits,
std::chrono::milliseconds timeout);
/**
* Poll just a single named source. Ordinally only used for testing
*/
size_t poll_just(RandomNumberGenerator& rng, const std::string& src);
Entropy_Sources() {}
explicit Entropy_Sources(const std::vector<std::string>& sources);
private:
std::vector<std::unique_ptr<Entropy_Source>> m_srcs;
};
}
#endif
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