A customer code word issuing machine is provided wherein a customer manually inputs to the machine his secret password. The machine encodes the password and displays his corresponding issued code word. A verification machine is provided which includes a dial or keyboard for manually inputting the customer's password and the issued code word. The verification machine encodes the inputted password to derive an output for comparison with the manually inputted code word to derive an output indicative of the truth or falseness of the match of the code word with the respective password. The verification machine may be employed to open a lock, to allow use of a credit card for a telephone call, purchase of goods, etc.