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/**
* EntropySource Header File
* (C) 2008-2009 Jack Lloyd
*/
#ifndef BOTAN_ENTROPY_SOURCE_BASE_H__
#define BOTAN_ENTROPY_SOURCE_BASE_H__
#include <botan/buf_comp.h>
#include <string>
#include <utility>
namespace Botan {
/**
* Class used to accumulate the poll results of EntropySources
*/
class Entropy_Accumulator
{
public:
Entropy_Accumulator(BufferedComputation& sink, u32bit goal) :
entropy_sink(sink), entropy_goal(goal), collected_bits(0) {}
/**
@return cached I/O buffer for repeated polls
*/
MemoryRegion<byte>& get_io_buffer(u32bit size)
{ io_buffer.create(size); return io_buffer; }
u32bit bits_collected() const { return collected_bits; }
bool polling_goal_achieved() const
{ return (collected_bits >= entropy_goal); }
u32bit desired_remaining_bits() const
{
return (collected_bits >= entropy_goal) ? 0 : (entropy_goal - collected_bits);
}
void add(const void* bytes, u32bit length, u32bit estimated_entropy)
{
entropy_sink.update(reinterpret_cast<const byte*>(bytes), length);
collected_bits += std::min(estimated_entropy, length * 8);
}
template<typename T>
void add(const T& v, u32bit estimated_entropy)
{
add(&v, sizeof(T), estimated_entropy);
}
private:
BufferedComputation& entropy_sink;
SecureVector<byte> io_buffer;
u32bit entropy_goal, collected_bits;
};
/**
* Abstract interface to a source of (hopefully unpredictable) system entropy
*/
class BOTAN_DLL EntropySource
{
public:
virtual std::string name() const = 0;
virtual void poll(Entropy_Accumulator& accum) = 0;
virtual ~EntropySource() {}
};
}
#endif
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