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// randpool.cpp - written and placed in the public domain by Wei Dai
// 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).
#include "pch.h"
#ifndef CRYPTOPP_IMPORTS
#include "randpool.h"
#include "aes.h"
#include "sha.h"
#include "hrtimer.h"
#include <time.h>
NAMESPACE_BEGIN(CryptoPP)
RandomPool::RandomPool()
: m_pCipher(new AES::Encryption), m_keySet(false)
{
memset(m_key, 0, m_key.SizeInBytes());
memset(m_seed, 0, m_seed.SizeInBytes());
}
void RandomPool::IncorporateEntropy(const byte *input, size_t length)
{
SHA256 hash;
hash.Update(m_key, 32);
hash.Update(input, length);
hash.Final(m_key);
m_keySet = false;
}
void RandomPool::GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size)
{
if (size > 0)
{
if (!m_keySet)
m_pCipher->SetKey(m_key, 32);
Timer timer;
TimerWord tw = timer.GetCurrentTimerValue();
CRYPTOPP_COMPILE_ASSERT(sizeof(tw) <= 16);
*(TimerWord *)m_seed.data() += tw;
time_t t = time(NULL);
CRYPTOPP_COMPILE_ASSERT(sizeof(t) <= 8);
*(time_t *)(m_seed.data()+8) += t;
do
{
m_pCipher->ProcessBlock(m_seed);
size_t len = UnsignedMin(16, size);
target.ChannelPut(channel, m_seed, len);
size -= len;
} while (size > 0);
}
}
NAMESPACE_END
#endif
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