#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()
{
for (int i=0; i<2; i++)
{
RandomPoolCipher cipher(key);
CFBEncryption cfb(cipher, pool+pool.size-cipher.BlockSize());
cfb.ProcessString(pool, pool.size);
memcpy(key, pool, key.size);
}
addPos = 0;
getPos = key.size;
}
void RandomPool::Put(byte inByte)
{
if (addPos == pool.size)
Stir();
pool[addPos++] ^= inByte;
getPos = pool.size; }
void RandomPool::Put(const byte *inString, unsigned int length)
{
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; }
}
byte RandomPool::GenerateByte()
{
if (getPos == pool.size)
Stir();
return pool[getPos++];
}
void RandomPool::GenerateBlock(byte *outString, unsigned int size)
{
unsigned t;
while (size > (t = pool.size - getPos))
{
memcpy(outString, pool+getPos, t);
outString += t;
size -= t;
Stir();
}
if (size)
{
memcpy(outString, pool+getPos, size);
getPos += size;
}
}
NAMESPACE_END