private void SetupEncRoundKeys() {
_keySize.ShouldNotBeZero("_keySize");
_masterKey.ShouldNotBeNull("_masterKey");
if(_encRoundKeys == null)
_encRoundKeys = new int[4 * (_numberOfRounds + 1)];
_decRoundKeys = null;
DoEncKeySetup(_masterKey, _encRoundKeys, _keySize);
}