Towards Tiny Trusted Third Parties

Many security protocols hypothesize the existence of a trusted third party (TTP) to ease handling of computation and data too sensitive for the other parties involved. Subsequent discussion usually dismisses these protocols as hypothetical or impractical, under the assumption that trusted third parties cannot exist. However, the last decade has seen the emergence of hardware-based devices that, to high assurance, can carry out computation unmolested; emerging research promises more. In theory, such devices can perform the role of a trusted third party in real-world problems. In practice, we have found problems. The devices aspire to be general-purpose processors but are too small to accommodate real-world problem sizes. The small size forces programmers to hand-tune each algorithm anew, if possible, to fit inside the small space without losing security. This tuning heavily uses operations that general-purpose processors do not perform well. Furthermore, perhaps by trying to incorporate too much functionality, current devices are also too expensive to deploy widely. Our current research attempts to overcome these barriers, by focusing on the effective use of tiny TTPs (T3Ps). To eliminate the programming obstacle, we used our experience building hardware TTP apps to design and prototype an efficient way to execute arbitrary programs on T3Ps while preserving the critical trust properties. To eliminate the performance and cost obstacles, we are currently examining the potential hardware design for a T3P optimized for these operations. In previous papers, we reported our work on the programming obstacle. In this paper, we examine the potential hardware designs. We estimate that such a T3P could outperform existing devices by several orders of magnitude, while also having a gate-count of only 30K-60K, one to three orders of magnitude smaller than existing devices.