All elections by the citizens, except for such town officers as may by law be directed to be otherwise chosen, shall be by ballot, or by such other method as may be prescribed by law, provided that secrecy in voting be preserved. The legislature shall provide for identification of voters through their signatures in all cases where personal registration is required and shall also provide for the signatures, at the time of voting, of all persons voting in person by ballot or voting machine, whether or not they have registered in person, save only in cases of illiteracy or physical disability.