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// randpool.cpp - written and placed in the public domain by Wei Dai
// The algorithm in this module comes from PGP's randpool.c
#include "pch.h"
#include "randpool.h"
#include "mdc.h"
#include "sha.h"
#include "modes.h"
NAMESPACE_BEGIN(CryptoPP)
typedef MDC<SHA> RandomPoolCipher;
RandomPool::RandomPool(unsigned int poolSize)
: pool(poolSize), key(RandomPoolCipher::DEFAULT_KEYLENGTH)
{
assert(poolSize > key.size());
addPos=0;
getPos=poolSize;
memset(pool, 0, poolSize);
memset(key, 0, key.size());
}
void RandomPool::Stir()
{
CFB_Mode<RandomPoolCipher>::Encryption cipher;
for (int i=0; i<2; i++)
{
cipher.SetKeyWithIV(key, key.size(), pool.end()-cipher.IVSize());
cipher.ProcessString(pool, pool.size());
memcpy(key, pool, key.size());
}
addPos = 0;
getPos = key.size();
}
unsigned int RandomPool::Put2(const byte *inString, unsigned int length, int messageEnd, bool blocking)
{
unsigned t;
while (length > (t = pool.size() - addPos))
{
xorbuf(pool+addPos, inString, t);
inString += t;
length -= t;
Stir();
}
if (length)
{
xorbuf(pool+addPos, inString, length);
addPos += length;
getPos = pool.size(); // Force stir on get
}
return 0;
}
unsigned int RandomPool::TransferTo2(BufferedTransformation &target, unsigned long &transferBytes, const std::string &channel, bool blocking)
{
if (!blocking)
throw NotImplemented("RandomPool: nonblocking transfer is not implemented by this object");
unsigned int t;
unsigned long size = transferBytes;
while (size > (t = pool.size() - getPos))
{
target.ChannelPut(channel, pool+getPos, t);
size -= t;
Stir();
}
if (size)
{
target.ChannelPut(channel, pool+getPos, size);
getPos += size;
}
return 0;
}
byte RandomPool::GenerateByte()
{
if (getPos == pool.size())
Stir();
return pool[getPos++];
}
void RandomPool::GenerateBlock(byte *outString, unsigned int size)
{
ArraySink sink(outString, size);
TransferTo(sink, size);
}
NAMESPACE_END
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