// randpool.h - written and placed in the public domain by Wei Dai

//! \file randpool.h
//! \brief Class file for Randomness Pool

#ifndef CRYPTOPP_RANDPOOL_H
#define CRYPTOPP_RANDPOOL_H

#include "cryptlib.h"
#include "filters.h"
#include "secblock.h"
#include "smartptr.h"
#include "aes.h"

NAMESPACE_BEGIN(CryptoPP)

//! \brief Randomness Pool
//! \details RandomPool can be used to generate cryptographic quality pseudorandom bytes
//!   after seeding the pool with IncorporateEntropy(). Internally, the generator uses
//!   AES-256 to produce the stream. Entropy is stirred in using SHA-256.
//! \details RandomPool used to follow the design of randpool in PGP 2.6.x,
//!   but as of version 5.5 it has been redesigned to reduce the risk
//!   of reusing random numbers after state rollback (which may occur
//!   when running in a virtual machine like VMware).
class CRYPTOPP_DLL RandomPool : public RandomNumberGenerator, public NotCopyable
{
public:
	//! \brief Construct a RandomPool
	RandomPool();

	bool CanIncorporateEntropy() const {return true;}
	void IncorporateEntropy(const byte *input, size_t length);
	void GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size);

	// for backwards compatibility. use RandomNumberSource, RandomNumberStore, and RandomNumberSink for other BufferTransformation functionality
	void Put(const byte *input, size_t length) {IncorporateEntropy(input, length);}

private:
	FixedSizeAlignedSecBlock<byte, 16, true> m_seed;
	FixedSizeAlignedSecBlock<byte, 32> m_key;
	member_ptr<BlockCipher> m_pCipher;
	bool m_keySet;
};

NAMESPACE_END

#endif
