During the last years many RFID authentication protocols have been proposed with major or minor success (van Deursen and Radomirović (2008)). Juels (2004) introduced a different and novel problem that aims to evidence that two tags have been simultaneously scanned. He called this kind of evidence a yoking-proof that is supposed to be verifiable offline. Then, some authors suggested the generalization of the proof for a larger number of tags. In this paper, we review the literature published in this research topic and show the security flaws of the proposed protocols, named RFID groupingproofs generally. More precisely, we cryptanalyze five of the most recent schemes and we also show how our techniques can be applied to older proposals. We provide some guidelines that should be followed to design secure protocols and preclude past errors. Finally, we present a yoking-proof for low-cost RFID tags, named Kazahaya, that conforms to the proposed guidelines. Keywords:RFID; Grouping-proof; Security; Privacy, Cryptanalysis * Corresponding author Email addresses: P.PerisLopez@tudelft.nl (Pedro Peris-Lopez), Preprint submitted to Journal of Network and Computer Applications March 25, 2010A c c e p t e d m a n u s c r i p t

Errors involving medication administration can be costly, both in financial and in human terms. Indeed, there is much potential for errors due to the complexity of the medication administration process. Nurses are often singled out as the only responsible of these errors because they are in charge of drug administration. Nevertheless, the interventions of every actor involved in the process and the system design itself contribute to errors [23]. Proper inpatient medication safety systems can help to reduce such errors in hospitals. In this paper, we review in depth two recent proposals [7,12] that pursue the aforementioned objective. Unfortunately, they fail in their attempt mainly due to their security faults but interesting ideas can be drawn from both. These security faults refer to impersonation and replay attacks that could produce the generation of a forged proof stating that certain medication was administered to an inpatient when it was not. We propose a leading-edge solution to enhance inpatient medication safety based on RFID technology that overcomes these weaknesses. Our solution, named Inpatient Safety RFID system (IS-RFID), takes into account the Information Technology (IT) infrastructure of a hospital and covers every phase of the drug administration process. From a practical perspective, our system can be easily integrated within hospital IT infrastructures, has a moderate cost, is very ease to use and deals with security aspects as a key point.

Deduplication is a widely used technique in storage services, since it affords a very efficient usage of resourcesbeing especially effective for consumer-grade storage services (e.g. Dropbox). Deduplication has been shown to suffer from several security weaknesses, the most severe ones enabling a malicious user to obtain possession of a file it is not entitled to. Standard solutions to this problem require users to prove possession of data prior to its upload. Unfortunately, the schemes proposed in the literature are very taxing on either the server or the client side. In this paper, we introduce a novel solution based on Bloom filters that provides a flexible, scalable, and provably secure solution to the weaknesses of deduplication, and that overcomes the deficiencies of existing approaches. We provide a formal description of the scheme, a thorough security analysis, and compare our solution against multiple existing ones, both analytically and by means of extensive benchmarking. Our results confirm the quality and viability of our approach.