A chameleon-hash function is a hash function that involves a trapdoor the knowledge of which allows one to find arbitrary collisions in the domain of the function. In this paper, we introduce the notion of chameleon-hash functions with ephemeral trapdoors. Such hash functions feature additional, i.e., ephemeral, trapdoors which are chosen by the party computing a hash value. The holder of the m...

In this paper the possibilities to automate black-box testing through formal requirement specifications are explored. More precisely, the formal method VDM (Vienna Development Method) serves to demonstrate that abstract requirement models can be used as test oracles for concrete software. The automation of the resulting testing frame-work is based on modern CASE-tools that support a light-weigh...

Despite its popularity, relatively little is known about the traffic characteristics of the Skype VoIP system and how they differ from other P2P systems. We describe an experimental study of Skype VoIP traffic conducted over a five month period, where over 82 million datapoints were collected regarding the population of online clients, the number of supernodes, and their traffic characteristics...

Constructions of cryptographic primitives based on general assumptions (e.g., one-way functions) tend to be less efficient than constructions based on specific (e.g., number-theoretic) assumptions. This has prompted a recent line of research aimed at investigating the best possible efficiency of (black-box) cryptographic constructions based on general assumptions. Here, we present bounds on the...

We interpret real-valued black-box optimization problems over continuous domains as black-box landscapes. The performance of a given optimization heuristic on a given problem largely depends on the characteristics of the corresponding landscape. Designing statistical measures that can be used to classify landscapes and quantify their topographical properties is hence of great importance. We tra...

This paper describes a network management tool. Visits to organizations of all sizes reveal that more than 95% of them are empty-handed as far as network management tools are concerned and pursue ad hoc management techniques. We argue that this sad state of affairs is due to the lack of cheap, easy to use tools. Although we don't solve the problem completely by providing such a tool, we show ho...

Since its inception, crowdsourcing has been considered a black-box approach to solicit labor from a crowd of workers. Furthermore, the “crowd” has been viewed as a group of independent workers dispersed all over the world. Recent studies based on in-person interviews have opened up the black box and shown that the crowd is not a collection of independent workers, but instead that workers commun...

Three building blocks for test guidance algorithms, the step evaluation, the state evaluation and the evaluation order, are proposed in this paper. We show how a simple family of coverage criteria can be used to evaluate individual testing steps, and how the nondeterministic behaviour of the tested system can be handled and longer term test step plans created with the state evaluation. We use t...

Although seemingly simple, tensegrity structures are complex in nature which makes them both ideal for use in robotics and difficult to construct. We work to develop a protocol for constructing tensegrities more easily. We consider attaching a tensegrity’s springs to the appropriate locations on some planar arrangement of attached struts. Once all of the elements of the structure are connected,...