Bogdan Carbunar

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We introduce a new practical mechanism for remote data storage with efficient access pattern privacy and correctness. A storage client can deploy this mechanism to issue encrypted reads, writes, and inserts to a potentially curious and malicious storage service provider, without revealing information or access patterns. The provider is unable to establish(More)
While recent technological advances have motivated large-scale deployment of RFID systems, a number of critical design issues remain unresolved. In this paper we address two important problems associated with RFIDs. The first problem deals with detecting redundant RFID readers (the redundant-reader problem). A related second problem is one of accurately(More)
Securing the sensitive data stored and accessed from mobile devices makes user authentication a problem of paramount importance. The tension between security and usability renders however the task of user authentication on mobile devices a challenging task. This paper introduces FAST (Fingergestures Authentication System using Touchscreen), a novel(More)
Existing mechanisms for querying wireless sensor networks leak client interests to the servers performing the queries. The leaks are not only in terms of specific regions of interest but also of client access patterns. In this article we introduce the problem of preserving the privacy of clients querying a wireless sensor network owned by untrusted(More)
We study the problem of detecting and eliminating redundancy in a sensor network with a view to improving energy efficiency, while preserving the network's coverage. We also examine the impact of redundancy elimination on the related problem of coverage-boundary detection. We reduce both problems to the computation of Voronoi diagrams, prove and achieve(More)
We design and analyze the first practical anonymous payment mechanisms for network services. We start by reporting on our experience with the implementation of a routing micropayment solution for Tor. We then propose micropayment protocols of increasingly complex requirements for networked services, such as P2P or cloud-hosted services. The solutions are(More)
In this paper we study two important problems - coverage-boundary detection and implementing distributed hash tables in ad-hoc wireless networks. These problems frequently arise in service location and relocation in wireless networks. For the centralized coverage-boundary problem we prove a /spl Omega/(n log n) lower bound for n devices. We show that both(More)
In the past few years, outsourcing private data to untrusted servers has become an important challenge. This raises severe questions concerning the security and privacy of the data on the external storage. In this paper we consider a scenario where multiple clients want to share data on a server, while hiding all access patterns. We propose here a first(More)
Due to the increasing popularity of mobile technologies, sensitive user information is often stored on mobile devices. However, the essential task of mobile user authentication is rendered more challenging by the conflicting requirements of security and usability: usable solutions are often insecure, while secure solutions hinder device accessibility. In(More)