Smart cards in hostile environments

One often hears the claim that smart cards are the solution to a number of security problems, including those arising in point-of-sale systems. In this paper, we characterize the minimal properties necessary for the secure smart card point-of-sale transactions. Many proposed systems fail to provide these properties: problems arise from failures to provide secure communication channels between the user and the smart card while operating in a potentially hostile environment (such as a point-of-sale application.) Moreover, we discuss several types of modifications that can be made to give smart cards additional input/output capacity with a user, and describe how this additional I/O can address the hostile environment problem. We give a notation for describing the effectiveness of smart cards under various environmental assumptions. We discuss several security equivalences among different scenarios for smart cards in hostile environments. Using our notation, these equivalences include: ff...