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Radio frequency identification systems with passive tags are powerful tools for object identification. However, if multiple tags are to be identified simultaneously, messages from the tags can collide and cancel each other out. Therefore, multiple read cycles have to be performed in order to achieve a high recognition rate. For a typical stochastic(More)
— We investigate the applicability of passive RFID systems to the task of identifying multiple tagged objects simultaneously, assuming that the number of tags is not known in advance. We present a combinatorial model of the communication mechanism between the reader device and the tags, and use this model to derive the optimal parameter setting for the(More)
Smartcards can be seen as service providing entities that implement a secure, tamper-proof storage and offer computational resources which make them ideally suited for a variety of tasks such as authentication, management of personal profiles, and other kinds of secure information processing. Integration of smartcards into networked environments though, has(More)
— The reliability of wireless sensor networks (WSN) is affected by faults that may occur due to various reasons such as malfunctioning hardware, software glitches, dislocation, or environmental hazards, e.g. fire or flood. A WSN that is not prepared to deal with such situations may suffer a reduction in overall lifetime, or lead to hazardous consequences in(More)
In this paper we examine requirements for an infrastructure that supports implementation and deployment of smart things in the real world. We describe a case study (RFID Chef) where kitchen items and ingredients, equipped with remotely accessible electronic tags, drive an interactive context-aware recipe finder through the use of an event-based(More)
This paper explores the design space for message authenti-cation in sensor networks. Several types of authentication are put into relation: end-to-end, hop-to-hop, and physical and virtual multipath au-thentication. While end-to-end authentication provides the highest and most general security level, it may be too costly or impractical to implement. On the(More)
The paper presents a novel approach t o J a v a b yte code ver-iication: The veriication process is performed ooine" on a network server, instead of incorporating it in the client. Furthermore, the most critical part of the veriication process is based upon a formal model and uses a model checker for checking the veriication conditions. The result of the(More)
The severe resource restrictions of computer-augmented everyday artifacts imply substantial problems for the design of applications in smart environments. Some of these problems can be overcome by exploiting the resources, I/O interfaces, and computing capabilities of nearby mobile devices in an ad hoc fashion. We identify the means by which smart objects(More)