P Value transfer systems enabling security and unobservability; IFIP/Sec. '86

In present-day cashless payment systems, the banks and (by installing a Trojan Horse) even the manufacturers of the computer equipment used could easily observe who pays what amount to whom and when. With the increasing digitization of these systems, e.g. point-of-sale terminals and home banking, the amount of transaction data and their computerization drastically increases. Thereby, these payment systems become completely unacceptable, since compiling dossiers on the lifestyle and whereabouts of all clients will become easy. Therefore, we describe the digital payment systems enabling unobservability of clients and arrange them in a general model to compare their different degrees of unobservability and their different levels of security. Since no single system has all desired features, we propose a suitable synthesis. The use of such payment systems for unobservable value exchange over a network (e.g. money against information) between two remote parties poses an additional security problem: the lack of a simultaneous exchange causes a temporary advantage for one party, who could then stop communication. But third parties can be used to overcome this problem. We compare two rather different approaches using third parties. The first tries to provide security by third parties identifyin

Unconditional Sender and Recipient Untraceability in spite of Active Attacks - Some Remarks

...................................................................................................1 2 Unconditional sender untraceability.............................................................2 2.1 Superposed sending ................................................................................2 2.2 Efficient and anonymity preserving multi-access protocols....................................5 2.3 Some remarks on sender untraceability schemes................................................8 3 Active attacks on untraceability ...................................................................9 3.1 Reliable broadcast................................................................................. 10 3.2 Fail-stop broadcast................................................................................ 11 3.2.1 Comparison of input characters ....................................................... 11 3.2.2 Message dependent key generation ...........................................

Optimizing and Load Balancing Metacomputing Applications

While the theoretical possibilities of metacomputing, in the sense of “heterogeneous supercomputing using WANs”, are obvious, it is difficult to utilize this potential in practice. In this paper, a programming model and communication library are presented which enable an efficient distribution of applications on a metacomputer. This is achieved by communication optimizations and a good load balance even for linked computers with considerably different computational speeds. First practical results show the benefits of the optimizations.

How to Realize Data-Parallel Algorithmic Skeletons with C++

Many authors have proposed the use of algorithmic skeletons as a high level, machine independent means of developing parallel applications. Until now their implementation and use was restricted to either functional-, or sophisticated imperative languages. In this paper we will show that C++ provides almost all features that are necessary to implement algorithmic skeletons and identify currying as the only one being not an intrinsic of the language. We will demonstrate how to add currying to the language by relying on language-immanent features and how to realize it without having a negative influence on the runtime performance