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// randpool.h - written and placed in the public domain by Wei Dai
//! \file randpool.h
//! \brief Class file for 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. At version 5.5
//! RandomPool was redesigned to reduce the risk of reusing random numbers after state
//! rollback (which may occur when running in a virtual machine like VMware or a hosted
//! environment).
//! \details If you need the pre-Crypto++ 5.5 generator then you can find it with:
//! <pre>
//! $ git clone https://github.com/weidai11/cryptopp cryptopp-ancient
//! $ cryptopp-ancient
//!
//! # Checkout the RandomPool change
//! $ git checkout f41245df6fb9b85574260eca9cd32777e8ab5136
//!
//! # Go back one more
//! git checkout HEAD~1
//!
//! $ grep 'MDC<SHA>' *.h *.cpp
//! randpool.cpp:typedef MDC<SHA> RandomPoolCipher;
//! </pre>
//! \since Crypto++ 4.0 (PGP 2.6.x style), Crypto++ 5.5 (AES-256 based)
#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)
//! \class RandomPool
//! \brief Randomness Pool based on AES-256
//! \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. At version 5.5
//! RandomPool was redesigned to reduce the risk of reusing random numbers after state
//! rollback (which may occur when running in a virtual machine like VMware or a hosted
//! environment).
//! \since Crypto++ 4.0 (PGP 2.6.x style), Crypto++ 5.5 (AES-256 based)
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
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