Minimizing information leakage of tree-based RFID authentication protocols using alternate tree-walking

The privacy of efficient tree-based RFID authentication protocols is heavily dependent on the branching factor on the top layer. Indefinitely increasing the branching factor, however, is not a viable option. This paper proposes the alternate-tree walking scheme as well as two protocols to circumvent this problem. The privacy of the resulting protocols is shown to be comparable to that of linear-time protocols, where there is no leakage of information, whilst reducing the computational load of the database by one-third of what is required of tree-based protocols during authentication. We also identify and address a limitation in quantifying privacy in RFID protocols

Forward-secure hierarchical predicate encryption

Secrecy of decryption keys is an important pre-requisite for security of any encryption scheme and compromised private keys must be immediately replaced. \emph{Forward Security (FS)}, introduced to Public Key Encryption (PKE) by Canetti, Halevi, and Katz (Eurocrypt 2003), reduces damage from compromised keys by guaranteeing confidentiality of messages that were encrypted prior to the compromise event. The FS property was also shown to be achievable in (Hierarchical) Identity-Based Encryption (HIBE) by Yao, Fazio, Dodis, and Lysyanskaya (ACM CCS 2004). Yet, for emerging encryption techniques, offering flexible access control to encrypted data, by means of functional relationships between ciphertexts and decryption keys, FS protection was not known to exist.\smallskip In this paper we introduce FS to the powerful setting of \emph{Hierarchical Predicate Encryption (HPE)}, proposed by Okamoto and Takashima (Asiacrypt 2009). Anticipated applications of FS-HPE schemes can be found in searchable encryption and in fully private communication. Considering the dependencies amongst the concepts, our FS-HPE scheme implies forward-secure flavors of Predicate Encryption and (Hierarchical) Attribute-Based Encryption.\smallskip Our FS-HPE scheme guarantees forward security for plaintexts and for attributes that are hidden in HPE ciphertexts. It further allows delegation of decrypting abilities at any point in time, independent of FS time evolution. It realizes zero-inner-product predicates and is proven adaptively secure under standard assumptions. As the ``cross-product" approach taken in FS-HIBE is not directly applicable to the HPE setting, our construction resorts to techniques that are specific to existing HPE schemes and extends them with what can be seen as a reminiscent of binary tree encryption from FS-PKE

The Politics of Official English: Exploring the Intentions and the Outcomes behind English-Only Policies in the United States

Although the Constitution did not declare English the official language of the United States, its complete linguistic dominance in such a linguistically diverse nation is unparalleled. Despite its supremacy, the last three decades have witnessed a renewed nationalistic movement that claims the role of English is threatened and that its establishment as the official language of the United States is crucial to protect the language and the unity of the nation. So far, attempts to institutionalize English at the federal level have failed, but 28 states have adopted English as their official language and/or legislation that limits the use of languages other than English in public schools, 25 of them since 1980. The present dissertation, which draws from critical discourse analysis as a theoretical framework and methodological approach, analyzes the discursive and generic structure, and the rationale and stated outcomes, of official English policies. These policies are examined in relation to the socio-historical context in which they were approved, the strategies of legitimation of those policies, the definition and interpretation of key terms, and the implications for the mutual respect and understanding of the social groups affected by the legislation and for society at large. Using a logistic regression model, this dissertation captures relevant social, economic, educational, and geopolitical indicators that show a statistical relation to official English policies and may shed light on the reasoning behind them. Finally, the dissertation compares the state expenditures on language programs for linguistic minorities in K-12 public schools and the outcomes of English learners in the two groups of states— those with and without official English policies. Consistent with findings from previous studies, the results of this study indicate that official English legislation seems to respond to a conservative ideology that seeks to establish a mechanism of internal colonization. In contrast to its stated outcomes, the legislation does not have any relation to increasing access to English in terms of funding for the education of linguistic minority students or to their academic results. In sum, the official English movement may serve, in effect, as an instrument to protect the status quo and thus to perpetuate the privilege of some groups and the subordination of others

Denial-of-Service Resistance in Key Establishment

Denial of Service (DoS) attacks are an increasing problem for network connected systems. Key establishment protocols are applications that are particularly vulnerable to DoS attack as they are typically required to perform computationally expensive cryptographic operations in order to authenticate the protocol initiator and to generate the cryptographic keying material that will subsequently be used to secure the communications between initiator and responder. The goal of DoS resistance in key establishment protocols is to ensure that attackers cannot prevent a legitimate initiator and responder deriving cryptographic keys without expending resources beyond a responder-determined threshold. In this work we review the strategies and techniques used to improve resistance to DoS attacks. Three key establishment protocols implementing DoS resistance techniques are critically reviewed and the impact of misapplication of the techniques on DoS resistance is discussed. Recommendations on effectively applying resistance techniques to key establishment protocols are made

Denial of Service in Voice Over IP Networks

In this paper we investigate denial of service (DoS) vulnerabilities in Voice over IP (VoIP) systems, focusing on the ITU-T H.323 family of protocols. We provide a simple characterisation of DoS attacks that allows us to readily identify DoS issues in H.323 protocols. We also discuss network layer DoS vulnerabilities that affect VoIP systems. A number of improvements and further research directions are proposed

Optimal Fair Scheduling in S-TDMA Sensor Networks for Monitoring River Plumes

Underwater wireless sensor networks (UWSNs) are a promising technology to provide oceanographers with environmental data in real time. Suitable network topologies to monitor estuaries are formed by strings coming together to a sink node.This network may be understood as an oriented graph. A number of MAC techniques can be used in UWSNs, but Spatial-TDMA is preferred for fixed networks. In this paper, a scheduling procedure to obtain the optimal fair frame is presented, under ideal conditions of synchronization and transmission errors. The main objective is to find the theoretical maximum throughput by overlapping the transmissions of the nodes while keeping a balanced received data rate from each sensor, regardless of its location in the network. The procedure searches for all cliques of the compatibility matrix of the network graph and solves a Multiple-Vector Bin Packing (MVBP) problem. This work addresses the optimization problem and provides analytical and numerical results for both the minimum frame length and the maximum achievable throughput

Lessons learned from the implementation of a Service Management Office: the case of a World Food company in Latin America

[EN] This paper presents the case of evolution and lessons learned in information technology service management (ITSM) of a World Food Company in Latin America, with an emphasis on their process-driven strategy for integral transformation through the Information Technology Infrastructure Library (ITIL), as well as the creation of their Service Management Office (SMO). Their experience in implementing ITIL and an SMO presenting their roadmap and main challenges. As an extra added value, service quality has been enhanced through the use of business indicators and commitments from three perspectives: people, processes and technologies. These results reveal that the SMO has become a strategic complement for IT, in addition to being a fundamental element to ensure quality and efficiency in technology service management.Lucio Nieto, T.; Gonzalez-Bañales, D. (2020). Lessons learned from the implementation of a Service Management Office: the case of a World Food company in Latin America. Editorial Universitat Politècnica de València. 21-34. https://doi.org/10.4995/INN2019.2019.10048OCS213

Mixing in convective thermal fluxes in unsteady nonhomogeneous flows generating complex three dimensional vorticity patterns

Diffusion and scaling of the velocity and vorticity in a thermoelectric driven heating and cooling experimental device is presented in order to map the different patterns and transitions between two and three dimensional convection in an enclosure with complex driven flows. The size of the water tank is of 0.2 x 0.2 x 0.1 m and the heat sources or sinks can be regulated both in power and sign [1-3]. The thermal convective driven flows are generated by means of Peltier effects in 4 wall extended positions of 0.05 x 0.05 cm each. The parameter range of convective cell array varies strongly with the Topology of the boundary conditions. Side heat and momentum fluxes are a function of Rayleigh, Peclet and Nusselt numbers, [4-6] Visualizations are performed by PIV, Particle tracking and shadowgraph. The structure of the flow is shown by setting up a convective flow generated by buoyant heat fluxes. The experiments described here investigate high Prandtl number mixing using brine and fresh water in order to form a density interface and low Prandtl number mixing with temperature gradients. The evolution of the mixing fronts are compared and the topological characteristics of the merging of the convective structures are examined for different configurations. Based on two dimensional Vorticity spectral analysis, new techniques can be very useful to determine the evolution of scales considering the multi-fractal structure of the convective flows.Peer ReviewedPostprint (published version

Detección de incendios mediante identificación de humo con visión artificial en condiciones de iluminación variable

La detección de humo en áreas abiertas representa una gran dificultad para los medios convencionales para detección de incendios. Mientras que la mayoría de los dispositivos utilizados para monitorear la presencia de fuego, están diseñados para trabajar en contacto con alguno producto de la combustión, como la temperatura o la concentración de humo en el aire, las herramientas basadas en Visión Artificial aprovechan las características ópticas del fuego o del humo, permitiendo realizar el monitoreo y la detección de incendios a mayor distancia. Sin embargo, las condiciones de captura de las imágenes complica el proceso. Diferentes niveles de iluminación, condiciones climáticas, así como la presencia de otros objetos móviles reducen el nivel de exactitud de los algoritmos existentes para la detección de humo. El presente proyecto se enfoca en presentar una propuesta de algoritmo para detección de humo mediante Visión Artificial que afronta el problema de la variación en las detecciones debida a los cambios de iluminación ambiental. Con este propósito, se diseñó un algoritmo compuesto por distintas etapas que analizan las imágenes en busca de características estáticas o dinámicas del humo. El algoritmo propuesto es descrito en el quinto capítulo de este trabajo escrito. Inicialmente, parte de una etapa de pre-procesamiento que permite ajustar la resolución de las imágenes extraídas desde un video de entrada, balancear la iluminación de las imágenes y etiquetarlas para evaluar la herramienta. Posteriormente, se emplea una etapa que realiza la detección de movimiento, una de análisis de la dirección del movimiento, otra más para el análisis de la información obtenida en espacio de Wavelets y un par de etapas complementarias que analizan el color en espacio RGB y YCbCr. Finalmente, los resultados son evaluados por una etapa clasificadora basada en la herramienta AdaBoost, para realizar la toma de decisiones y notificar sobre una detección de incendio. El algoritmo propuesto es evaluado a partir de los criterios de exactitud Sensibilidad (el porcentaje de detecciones correctas realizadas) y Especificidad (el porcentaje de no- detecciones correctamente realizadas). Los resultados de exactitud descritos en el sexto capítulo del presente trabajo escrito, se contrastan con los obtenidos por otros algoritmos replicados a partir del estado del arte. A partir de los casos de prueba planteados para cada escenario de iluminación evaluado, se identificó una reducción en la variación de los resultados, es decir, el cambio en los porcentajes de sensibilidad y especificidad en diferentes condiciones de iluminación, es menor al obtenido por los algoritmos replicados