// iterative hash function
private byte[] Func()
{
byte[] INT_block = Utils.GetBigEndianBytes(_block);
_hmac.TransformBlock(_salt, 0, _salt.Length, _salt, 0);
_hmac.TransformFinalBlock(INT_block, 0, INT_block.Length);
byte[] temp = _hmac.Hash;
_hmac.Initialize();
byte[] ret = temp;
for (int i = 2; i <= _iterationCount; i++)
{
temp = _hmac.ComputeHash(temp);
for (int j = 0; j < _blockSize; j++)
{
ret[j] ^= temp[j];
}
}
_block++;
return(ret);
}