Efficiency is the bottleneck of many cryptographic protocols towards their practical application in different contexts. This holds true also in the context of electronic voting, where cryptographic protocols are used to ensure a diversity of security requirements, e.g. Secrecy and integrity of cast votes. A new and promising application area of electronic voting is boardroom voting, which in practice takes place very frequently and often on simple issues such as approving or refusing a budget. Hence, it is not a surprise that a number of cryptographic protocols for boardroom voting have been already proposed. In this work, we introduce a security model adequate for the boardroom voting context. Further, we evaluate the efficiency of four boardroom voting protocols, which to best of our knowledge are the only boardroom voting protocols that satisfy our security model. Finally, we compare the performance of these protocols in different election settings.

Since its development more than thirty years ago, the Dempster-Shafer theory has grown to a rich and powerful collection of tools and techniques to handle various types of uncertainty. Some of the added extensions seem to be indispensable elements, but a closer analysis reveals them to be hidden applications of Dempster's classical rule of combination. This analysis is the topic of this paper

In an a priori anonymous digitized world, notions such as authenticity and trust are of paramount importance. Unfortunately, the exact meaning of such key terms has never been consistently defined, and they are often used in an ambiguous way. In this paper, we introduce a new model for representing these fundamental notions in the context of rating systems in e-business applications as well as for public-key certification. When applied to existing systems, its goal is to shed light on the implicit assumptions actually made by the participants. As an example, we show that for the rating system used in eBay, there are a number of such implicit assumptions on which the drawn conclusions depend. A second example is PGP, where it turns out that the meaning of the (syntactically well-defined) certificates is not entirely clear.

This article discusses several implementation aspects for Dempster-Shafer belief functions. The main objective is to propose an appropriate representation of mass functions and efficient data structures and algorithms for the two basic operations of combination and marginalization. © 2003 Wiley Periodicals, Inc.

The goal of this article is to study the connection between the Dempster-Shafter theory (DST) and probabilistic argumentation systems (PASs). By introducing a general method to translate PASs into corresponding Dempster-Shafter belief potentials, its contribution is twofold. On the one hand, the article proposes PASs as a convenient and powerful modeling language to be put on top of the DST. On the other hand, it shows how to use the DST as an efficient computational tool for numerical computations in PASs. © 2003 Wiley Periodicals, Inc.

Resolution is an often used method for deduction in propositional logic. Here a proper organization of deduction is proposed which avoids redundant computations. It is based on a generic framework of decompositions and local computations as introduced by Shenoy and Shafer. The system contains the two basic operations with information, namely marginalization (or projection) and combination; the latter being an idempotent operation in the present case. The theory permits the conception of an architecture of distributed computing. As an important application assumption-based reasoning is discussed.