code: private final void init(boolean forEncryption, byte[] key)
  	{
  		WorkingKey = generateWorkingKey(key, forEncryption);
  		this.klen = key.length;
  		this.doEncrypt = forEncryption;
  	}
docs: initialise an AES cipher.
  
  @param forEncryption
  whether or not we are for encryption.
  @param key
  the key required to set up the cipher.
  @exception IllegalArgumentException
  if the params argument is inappropriate.