Abstract—TUAK is a new mutual authentication and key generation algorithm proposed by the Security Algorithm Group of Experts (SAGE) of the European Telecommunications Standards Institute (ETSI) and published by the Third Generation Partnership Project (3GPP). TUAK is based on the Keccak sponge function which has very different design principles to the pre-existing 3G MILENAGE algorithm and so promises a back-up/alternative in case algorithm vulnerabilities are discovered during long-term Machine-to-Machine (M2M) deployments. However, the practicality of implementing TUAK on currently deployed and/or future Subscriber Identity Module (SIM) cards is not well known. This paper describes the initial work and findings of a study in support of SAGE and GSMA to consider such implementation aspects.