void Stir()
{
const int length = 128;
byte[] randomness = new byte[length];
CryptographicallyRandomValuesFromOS (randomness);
AddRandomData (randomness);
// Discard early keystream, as per recommendations in:
// http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
for (int i = 0; i < 256; i++)
GetByte ();
count = STIR_INCREMENT_CONST;
}