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Publicações

Publicações por HASLab

2008

Secure biometric authentication with improved accuracy

Autores
Barbosa, M; Brouard, T; Cauchie, S; de Sousa, SM;

Publicação
INFORMATION SECURITY AND PRIVACY

Abstract
We propose a new hybrid protocol for cryptographically secure biometric authentication. The main advantages of the proposed protocol over previous solutions can be summarised as follows: (1) potential for much better accuracy using different types of biometric signals, including behavioural ones; and (2) improved user privacy, since user identities are not transmitted at any point in the protocol execution. The new protocol takes advantage of state-of-the-art identification classifiers, which provide not only better accuracy, but also the possibility to perform authentication without knowing who the user claims to be. Cryptographic security is based on the Paillier public key encryption scheme.

2007

GORDA: An open architecture for database replication

Autores
Correia, A; Pereira, J; Rodrigues, L; Carvalho, N; Vilaca, R; Oliveira, R; Guedes, S;

Publicação
Sixth IEEE International Symposium on Network Computing and Applications, Proceedings

Abstract

2007

Emergent structure in unstructured epidemic multicas

Autores
Carvalho, N; Pereira, J; Oliveira, R; Rodrigues, L;

Publicação
37TH ANNUAL IEEE/IFIP INTERNATIONAL CONFERENCE ON DEPENDABLE SYSTEMS AND NETWORKS, PROCEEDINGS

Abstract
In epidemic or gossip-based multicast protocols, each node simply relays each message to some random neighbors, such that all destinations receive it at least once with high probability. In sharp contrast, structured multicast protocols explicitly build and use a spanning tree to take advantage of efficient paths, and aim at having each message received exactly once. Unfortunately, when failures occur, the tree must be rebuilt. Gossiping thus provides simplicity and resilience at the expense of performance and resource efficiency. In this paper we propose a novel technique that exploits knowledge about the environment to schedide payload transmission when gossiping. The resulting protocol retains the desirable qualities of gossip, but approximates the performance of structured multicast. In some sense, instead of imposing structure by construction, we let it emerge from the operation of the gossip protocol. Experimental evaluation shows that this approach is effective even when knowledge about the environment is only approximate.

2007

On the use of a reflective architecture to augment database management systems

Autores
Carvalho, N; Correia, A; Pereira, J; Rodrigues, L; Oliveira, R; Guedes, S;

Publicação
JOURNAL OF UNIVERSAL COMPUTER SCIENCE

Abstract
The Database Management System ( DBMS) used to be a commodity software component, with well known standard interfaces and semantics. However, the performance and reliability expectations being placed on DBMSs have increased the demand for a variety add-ons, that augment the functionality of the database in a wide range of deployment scenarios, offering support for features such as clustering, replication, and self-management, among others. A well known software engineering approach to systems with such requirements is reflection. Unfortunately, standard reflective interfaces in DBMSs are very limited. Some of these limitations may be circumvented by implementing reflective features as a wrapper to the DBMS server. Unfortunately, these solutions comes at the expense of a large development effort and significant performance penalty.

2007

Visual Programming with Recursion Patterns in Interaction Nets

Autores
Mackie, I; Pinto, JS; Vilaça, M;

Publicação
ECEASST

Abstract
In this paper we propose to use Interaction Nets as a formalism for Visual Functional Programming. We consider the use of recursion patterns as a programming idiom, and introduce a suitable archetype/instantiation mechanism for interaction agents, which allows one to define agents whose behaviour is based on recursion patterns. © 2007, Universitatsbibliothek TU Berlin.

2007

A Higher-Order Calculus for Graph Transformation

Autores
Fernandez, M; Mackie, I; Pinto, JS;

Publicação
Electronic Notes in Theoretical Computer Science

Abstract
This paper presents a formalism for defining higher-order systems based on the notion of graph transformation (by rewriting or interaction). The syntax is inspired by the Combinatory Reduction Systems of Klop. The rewrite rules can be used to define first-order systems, such as graph or term-graph rewriting systems, Lafont's interaction nets, the interaction systems of Asperti and Laneve, the non-deterministic nets of Alexiev, or a process calculus. They can also be used to specify higher-order systems such as hierarchical graphs and proof nets of Linear Logic, or to specify the operational semantics of graph-based languages.

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