Conversely, how can we use private input to simulate private output? Consider a smart card containing an integral numeric keypad that but lacking human readable output capabilities. This smart card is inserted in a POS terminal providing (unsecure) output for the smart card. If the customer takes precautions to prevent observers from observing information typed into the smart card, the customer can provide the smart card with a one-time pad. The smart card could then encrypt data using the one-time pad. Since only the smart card and the customer are in possession of the one-time pad, they are the only parties able to read the message.