Henning Pagnia

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Recently, research has focused on enabling fair exchange between payment and electronically shipped items. The reason for this is the growing importance of Electronic Commerce and the increasing number of applications in this area. Although a considerable number of fair exchange protocols exist, they usually have been defined for special scenarios and thus(More)
Mobile agents have been advocated to support electronic commerce over the Internet. While being a promising paradigm, many intricate problems need to be solved to make this vision reality. The problem of fair exchange between two agents is one such fundamental problem. Informally speaking, this means to exchange two electronic items in such a way that(More)
As computer systems influence an increasingly large part of everyday life, our society is becoming more and more dependent upon correct and well-designed systems. This is especially obvious in mission critical applications, like flight control systems, where it is important that the system continually provides the respective service even in the presence of(More)
The notion of fairness is a very general concept and can be used to coin terms in many different application areas. Recently, the term fairness has appeared in the context of electronic commerce. Here, the term fair exchange refers to the problem that two parties want to swap some distinct items in a way which ensures that no participant can gain advantage(More)
Recently, many payment schemes for digital money have been proposed. In nearly all these schemes money can be spent only once and must then immediately be returned to the bank. The purpose of this paper is to show the advantages of a scheme which allows the recipient of the money to use it directly for further purchases. We discuss why existing schemes(More)
Replicating data in a distributed system is a suitable means for increasing the availability as well as the performance of data access operations. Unfortunately, there exists a trade-oo between these two properties: a replica control protocol which exhibits, e.g., a high read availability and low read operation costs usually suuers from low write(More)
Grid-based data replication protocols have been proven to be extremely eecient due to the high availability and the low cost of read and write operations they ooer. However, although each grid protocol uses logical grids, the semantics and interpreting algorithms vary from scheme to scheme. This has the disadvantage that switching from one protocol to(More)