code: public void zeroKey(){
  		for(int i = 0; i < key.length; i++){
  			key[i] = 0x0;
  		}
  		for(int i = 0; i < prehash.length; i++){
  			key[i] = 0x0;
  		}
  		cfg = false;
  	}
docs: Zero's out memory where the key is stored.
  After calling this method init() needs to be called again.