SnowShoe Stamps are small pieces of plastic with secret digital identities. SnowShoe have no batteries, power, circuitry, antenna, and moving parts and blur the boundaries between their digital and physical worlds. SnowShoe stamps let game developers bring physical digital experiences to mobile platforms. At the same time, they have been used as a physical factor of authentication for user log-in and POS transactions. Stamps work with all multi-touch mobile devices, and their software can be integrated into a project in mere minutes.