Physical authentication brings extra security to software authentication by adding real-world input to conventional authentication protocols. Existing solutions such as textual and graphical passwords are subject to brute force and shoulder sur fing attacks, while users are reluctant to use biometrics for identifi cation, due to its intrusiveness. This paper uses Hamiltonian tokens as authentication means. The proposed token structure offers many possible configurations ( i.e., passwords) and is small enough to be carried on a physical keychain. After presenting our general idea, we describe an e fficient algorithm to produce these tokens. Our procedure was validated by running a recognition campaign on a wide batch of synthetic samples, and experimented on prototypes manufactured using a commercial 3D-printer.
