Comunicacions a congressos (Matemàtica)

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    Open Access
    METMA X. Proceedings of the 10th International Workshop on Spatio-Temporal Modelling. Lleida (Spain) 1-3 June 2022
    (Edicions i Publicacions de la Universitat de Lleida, 2022) Comas Rodríguez, Carles; Mateu, Jorge
    METMA workshop comes to its 10th edition meaning 20 years of history since its first version held in Castellon (Spain) back in 2001. Since then, its location has been moving along through Spain, Portugal, France and Italy, and has become an international reference for space-time statistics. This edition was aimed to be held in 2020 but was postponed to 2022 due to covid pandemic, and thus it somehow will be remembered as the covid-time edition. The purpose of this conference is to promote the development and application of spatial, temporal, and mainly spatio-temporal statistical methods to different fields related to the environment. The general aim is to bring together practitioners and researchers of different areas and countries all over the world. Cross-disciplinary actions to solve environmental problems are very welcome. The scientific program ( features sessions covering topics on the latest advancements in theory, methods and applications, and presentations from keynotes, invited and a number of oral contributed and posters completes the program.
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    Open Access
    Parking Tickets for Privacy-Preserving Pay-by-Phone Parking
    (Association for Computing Machinery (ACM), 2019) Borges Llorens, Ricard; Sebé Feixas, Francesc
    Traditionally, the payment required for parking in regulated areas has been made through parking meters. In the last years, several applications which allow to perform these payments using a mobile device have appeared. In this paper we propose a privacy-preserving pay-by-phone parking system o ering the same privacy as the traditional paper- based method even assuming an internal attacker with full access to all the information managed by the system servers. Drivers'privacy is preserved without requiring them to trust any party. Furthermore, the system can tolerate that the mobile devices of drivers fall out of coverage while their cars are parked.
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    Open Access
    Improving a smart metering system using elliptic curves and removing the trusted dealer
    (2018) Garra Oronich, Ricard; Martínez Rodríguez, Santi; Miret, Josep M. (Josep Maria); Sebé Feixas, Francesc
    Fine-grained electricity consumption information has been proven to allow to infer people’s habits from their consumption patterns. Hence, smart metering systems need a secure way to regularly transmit the electricity consumption to the supplier in such a way that the privacy of customers is preserved. Several proposals can be found in the literature. Some of them, classified as aggregative solutions, organize the meters into groups and employ homomorphic cryptography in such a way that the supplier only obtains the aggregated consumption values of the meters in each group. In this paper we propose a technique which allows to remove the presence of a trusted dealer in one of the most efficient current proposals. Furthermore, we increase the overall performance of the resulting system by employing elliptic curve cryptography. The resulting system only requires a single message sent from each smart meter to its substation, without needing the meters to communicate among them. With the use of elliptic curve cryptography, the only relevant computation that the smart meters need to perform is a single elliptic curve point multiplication by a scalar. The system has been proven to be feasible and practical even for large neigborhoods including several thousands of meters.