TOMÁŠ ROSA
Tomáš Rosa graduated from the Dept. of Computer Science of the Faculty of Electrical Engineering of the Czech Technical University in Prague (CTU), in a combined study programme with the Faculty of Mathematics and Physics of Charles University in Prague. He received the Best Doctoral Work Award of the Rector of CTU for 2004. As a chief cryptologist, he worked on TOP SECRET information protection projects under Czech Act no. 148/1998 Coll. In the Czech Republic, he belongs to the group of pioneering researchers in the area of applied cryptanalysis which he promotes as a natural counterpart to the well-known paradigm of applied cryptography. He participates on various research projects in this area. As an information security expert with Raiffeisenbank, he is focused on applied cryptography and cryptanalysis in the area of embedded applications and devices.
THE DECLINE AND DAWN OF TWO-FACTOR AUTHENTICATION ON SMART PHONES
In this paper, we focus on two-factor authentication methods employed by smart phones. Regarding this platform, it is well-known that there are several risks that should be evaluated carefully when designing such applications. It actually turns out that it probably signalizes an emerging decline of two-factor authentication as we know it, for instance, from some contemporary banking applications. Smart phones, on the other hand, do not provide only new threats and vulnerabilities; they also promise to deliver an excellent mix of computational power, rich peripheral devices and applications right into the client’s hand. After having successfully mastered this part of mobile device evolution, we can hope to see a dawn of the two-factor authentication as we need it. We define three basic threat models that are connected with smart phones. For each model, we then present a typical effective way of how the risk can be mitigated. We do not strive to improve the smart phone platform itself. We basically accept that the particular threat can occur and we search for possible ways of how to mitigate the risk. To do this, we mainly employ techniques of redundancy-less encryption schemes, intensive explicit sensitive data wiping, and finally, we also touch on approaching technologies such as NFC-based authentication tokens bearing an independent display and buttons. We examine this topic solely from the viewpoint of the code that is running on the particular smart phone device, since we believe that this is the part that now deserves the greatest attention. To explain the countermeasures, we use easy-to-follow examples illustrating what can happen when something in our design goes wrong. Our aim is to explain the main principles, while unimportant technical details will be omitted for the sake of readability.
