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Wattenhofer et al. [WW04] derive a complicated distributed algorithm to compute a weighted matching of an arbitrary weighted graph, that is at most a factor 5 away from the maximum weighted matching of that graph. We show that a variant of the obvious sequential greedy algorithm [Pre99], that computes a weighted matching at most a factor 2 away from the(More)
The mifare Classic is the most widely used contactless smart card in the market. Its design and implementation details are kept secret by its manufacturer. This paper studies the architecture of the card and the communication protocol between card and reader. It reveals command codes and structure that so far were unknown. It also gives a practical,(More)
The ephemeral pairing problem requires two or more specific physical nodes in a wireless broadcast network, that do not yet know each other, to establish a short-term relationship between them. Such short-lived pairings occur, for example, when one pays at a check-out using a wireless wallet. This problem is equivalent to the ephemeral key exchange problem,(More)
Peer-to-peer (P2P) and grid systems allow their users to exchange information and share resources in a uniform and reliable manner. In an ideal world, users make roughly as much resources available as they use. In reality, this is not always the case, and some kind of currency or barter (called karma) is needed that can be exchanged for resources to limit(More)
In this paper we consider a model where malicious agents can corrupt hosts and move around in a network of processors. We consider a family of mobile-fault models MF(t n−1 , ρ). In MF(t n−1 , ρ) there are a total of n processors, the maximum number of mobile faults is t, and their roaming pace is ρ (for example, ρ = 3 means that it takes an agent at least 3(More)
The first generation of European e-passports will be issued in 2006. We discuss how borders are crossed regarding the security and privacy erosion of the proposed schemes, and show which borders need to be crossed to improve the security and the privacy protection of the next generation of e-passports. In particular we discuss attacks on Basic Access(More)
This paper studies the current 'identity cri-sis' caused by the substantial security, privacy and us-ability shortcomings encountered in existing systems for identity management. Some of these issues are well known, while others are much less understood. This paper brings them together in a single, comprehensive study and proposes recommendations to resolve(More)
In this paper we define the notion of a privacy design strategy. These strategies help to support privacy by design throughout the full software development life cycle, even before the design phase. Using current data protection legislation as point of departure we derive the following eight privacy design strategies: MINIMISE, HIDE, SEPARATE, AGGREGATE,(More)