Gelareh Taban

Towards a secure and interoperable DRM architecture

In this paper we look at the problem of interoperability of digital rights management (DRM)systems in home networks. We introduce an intermediate module called the Domain Interoperability Manager (DIM) to efficiently deal with the problem of content and license translation across different DRM regimes. We also consider the threat model specific to interoperability systems, and introduce threats such as the cross-compliancy and splicing attacks. We formalize the adversary model and define security of an interoperable DRM system with respect to this adversary. We finalize by proposing detailed protocols which achieve our security requirements. In order to achieve these requirements we provide novel applications of recently proposed proxy resignature and proxy re-encryption algorithms.

Two-server password-only authenticated key exchange

Typical protocols for password-based authentication assume a single server that stores all the information (e.g., the password) necessary to authenticate a user. An inherent limitation of this approach, assuming low-entropy passwords are used, is that the user@?s password is exposed if this server is ever compromised. To address this issue, it has been suggested to share a user@?s password information among multiple servers, and to have these servers cooperate (possibly in a threshold manner) when the user wants to authenticate. We show here a two-server version of the password-only key-exchange protocol of Katz, Ostrovsky, and Yung (the KOY protocol). Our work gives the first secure two-server protocol for the password-only setting (in which the user need remember only a password, and not the servers@? public keys), and is the first two-server protocol (in any setting) with a proof of security in the standard model. Our work thus fills a gap left by the work of MacKenzie et al. (2006) [31] and Di Raimondo and Gennaro (2006) [16]. As an additional benefit of our work, we show modifications that improve the efficiency of the original KOY protocol.

Privacy-Preserving Integrity-Assured Data Aggregation in Sensor Networks

Data aggregation in sensor network can improve both efficiency and privacy of network traffic.Recent work in integrity-assured data aggregation has considered aggregation as only an efficiency primitive. In this work, we address for the first time the problem of integrity-assured data aggregation with efficiency and privacy as a joint objective. Our solutions show the inherent tension between privacy-preservation and integrity-assurance of data aggregation.

Efficient Handling of Adversary Attacks in Aggregation Applications

Current approaches to handling adversary attacks against data aggregation in sensor networks either aim exclusively at the detection of aggregate data corruption or provide rather inefficient ways to identify the nodes captured by an adversary. In contrast, we propose a distributed algorithm for efficient identification of captured nodes over a constant number of rounds, for an arbitrary number of captured nodes. We formulate our problem as a combinatorial group testing problem and show that this formulation leads not only to efficient identification of captured nodes but also to a precise cost-based characterization of when in-network aggregation retains its assumed benefits in a sensor network operating under persistent attacks.

Key establishment in heterogeneous self-organized networks

Traditional key pre-distribution schemes in sensor and ad hoc networks rely on the existence of a trusted third party to generate and distribute a key pool. The assumption of a single TTP however can be very strong in practice, especially when nodes belong to different domains and they come together in an ad hoc manner. In this work, we show the shortcomings of previous approaches [3,13] in terms of both efficiency and security. By incorporating a heterogeneous network, we show that we can dramatically reduce the load on resource constrained devices whilst also increasing their security. We also propose a new strengthened security model for self-organized ad hoc networks and evaluate the security of our protocol in this model.

Securing random key predistribution against semi-honest adversaries

Recently, Eschenauer and Gligor [6] proposed a model for random key predistribution in distributed sensor networks. In this paper we study the security of this model against a semi-honest adversary who compromises nodes, and present a key establishment algorithm that is provably secure. This is the first and only protocol that can guarantee security against semi-honest adversaries in an analytical framework.