1,916 research outputs found
LIPIcs, Volume 251, ITCS 2023, Complete Volume
LIPIcs, Volume 251, ITCS 2023, Complete Volum
Formal Verification of Verifiability in E-Voting Protocols
Election verifiability is one of the main security properties of e-voting protocols, referring to the ability of independent entities, such as voters or election observers, to validate the outcome of the voting process. It can be ensured by means of formal verification that applies mathematical logic to verify the considered protocols under well-defined assumptions, specifications, and corruption scenarios. Automated tools allow an efficient and accurate way to perform formal verification, enabling comprehensive analysis of all execution scenarios and eliminating the human errors in the manual verification. The existing formal verification frameworks that are suitable for automation are not general enough to cover a broad class of e-voting protocols. They do not cover revoting and cannot be tuned to weaker or stronger levels of security that may be achievable in practice. We therefore propose a general formal framework that allows automated verification of verifiability in e-voting protocols. Our framework is easily applicable to many protocols and corruption scenarios. It also allows refined specifications of election procedures, for example accounting for revote policies.
We apply our framework to the analysis of several real-world case studies, where we capture both known and new attacks, and provide new security guarantees. First, we consider Helios, a prominent web-based e-voting protocol, which aims to provide end-to-end verifiability. It is however vulnerable to ballot stuffing when the voting server is corrupt. Second, we consider Belenios, which builds upon Helios and aims to achieve stronger verifiability, preventing ballot stuffing by splitting the trust between a registrar and the server. Both of these systems have been used in many real-world elections. Our third case study is Selene, which aims to simplify the individual verification procedure for voters, providing them with trackers for verifying their votes in the clear at the end of election. Finally, we consider the Estonian e-voting protocol, that has been deployed for national elections since 2005. The protocol has continuously evolved to offer better verifiability guarantees but has no formal analysis. We apply our framework to realistic models of all these protocols, deriving the first automated formal analysis in each case. As a result, we find several new attacks, improve the corresponding protocols to address their weakness, and prove that verifiability holds for the new versions
Advances and Applications of DSmT for Information Fusion. Collected Works, Volume 5
This fifth volume on Advances and Applications of DSmT for Information Fusion collects theoretical and applied contributions of researchers working in different fields of applications and in mathematics, and is available in open-access. The collected contributions of this volume have either been published or presented after disseminating the fourth volume in 2015 in international conferences, seminars, workshops and journals, or they are new. The contributions of each part of this volume are chronologically ordered.
First Part of this book presents some theoretical advances on DSmT, dealing mainly with modified Proportional Conflict Redistribution Rules (PCR) of combination with degree of intersection, coarsening techniques, interval calculus for PCR thanks to set inversion via interval analysis (SIVIA), rough set classifiers, canonical decomposition of dichotomous belief functions, fast PCR fusion, fast inter-criteria analysis with PCR, and improved PCR5 and PCR6 rules preserving the (quasi-)neutrality of (quasi-)vacuous belief assignment in the fusion of sources of evidence with their Matlab codes.
Because more applications of DSmT have emerged in the past years since the apparition of the fourth book of DSmT in 2015, the second part of this volume is about selected applications of DSmT mainly in building change detection, object recognition, quality of data association in tracking, perception in robotics, risk assessment for torrent protection and multi-criteria decision-making, multi-modal image fusion, coarsening techniques, recommender system, levee characterization and assessment, human heading perception, trust assessment, robotics, biometrics, failure detection, GPS systems, inter-criteria analysis, group decision, human activity recognition, storm prediction, data association for autonomous vehicles, identification of maritime vessels, fusion of support vector machines (SVM), Silx-Furtif RUST code library for information fusion including PCR rules, and network for ship classification.
Finally, the third part presents interesting contributions related to belief functions in general published or presented along the years since 2015. These contributions are related with decision-making under uncertainty, belief approximations, probability transformations, new distances between belief functions, non-classical multi-criteria decision-making problems with belief functions, generalization of Bayes theorem, image processing, data association, entropy and cross-entropy measures, fuzzy evidence numbers, negator of belief mass, human activity recognition, information fusion for breast cancer therapy, imbalanced data classification, and hybrid techniques mixing deep learning with belief functions as well
Certificates for decision problems in temporal logic using context-based tableaux and sequent calculi.
115 p.Esta tesis trata de resolver problemas de Satisfactibilidad y Model Checking, aportando certificados del resultado. En ella, se trabaja con tres lógicas temporales: Propositional Linear Temporal Logic (PLTL), Computation Tree Logic (CTL) y Extended Computation Tree Logic (ECTL). Primero se presenta el trabajo realizado sobre Certified Satisfiability. Ahí se muestra una adaptación del ya existente método dual de tableaux y secuentes basados en contexto para satisfactibilidad de fórmulas PLTL en Negation Normal Form. Se ha trabajado la generación de certificados en el caso en el que las fórmulas son insactisfactibles. Por último, se aporta una prueba de soundness del método. Segundo, se ha optimizado con Sat Solvers el método de Certified Satisfiability para el contexto de Certified Model Checking. Se aportan varios ejemplos de sistemas y propiedades. Tercero, se ha creado un nuevo método dual de tableaux y secuentes basados en contexto para realizar Certified Satisfiability para fórmulas CTL yECTL. Se presenta el método y un algoritmo que genera tanto el modelo en el caso de que las fórmulas son satisfactibles como la prueba en el caso en que no lo sean. Por último, se presenta una implementación del método para CTL y una experimentación comparando el método propuesto con otro método de similares características
Automated and foundational verification of low-level programs
Formal verification is a promising technique to ensure the reliability of low-level programs like operating systems and hypervisors, since it can show the absence of whole classes of bugs and prevent critical vulnerabilities. However, to realize the full potential of formal verification for real-world low-level programs one has to overcome several challenges, including: (1) dealing with the complexities of realistic models of real-world programming languages; (2) ensuring the trustworthiness of the verification, ideally by providing foundational proofs (i.e., proofs that can be checked by a general-purpose proof assistant); and (3) minimizing the manual effort required for verification by providing a high degree of automation. This dissertation presents multiple projects that advance formal verification along these three axes: RefinedC provides the first approach for verifying C code that combines foundational proofs with a high degree of automation via a novel refinement and ownership type system. Islaris shows how to scale verification of assembly code to realistic models of modern instruction set architectures-in particular, Armv8-A and RISC-V. DimSum develops a decentralized approach for reasoning about programs that consist of components written in multiple different languages (e.g., assembly and C), as is common for low-level programs. RefinedC and Islaris rest on Lithium, a novel proof engine for separation logic that combines automation with foundational proofs.Formale Verifikation ist eine vielversprechende Technik, um die Verlässlichkeit von grundlegenden Programmen wie Betriebssystemen sicherzustellen. Um das volle Potenzial formaler Verifikation zu realisieren, müssen jedoch mehrere Herausforderungen gemeistert werden: Erstens muss die Komplexität von realistischen Modellen von Programmiersprachen wie C oder Assembler gehandhabt werden. Zweitens muss die Vertrauenswürdigkeit der Verifikation sichergestellt werden, idealerweise durch maschinenüberprüfbare Beweise. Drittens muss die Verifikation automatisiert werden, um den manuellen Aufwand zu minimieren. Diese Dissertation präsentiert mehrere Projekte, die formale Verifikation entlang dieser Achsen weiterentwickeln: RefinedC ist der erste Ansatz für die Verifikation von C Code, der maschinenüberprüfbare Beweise mit einem hohen Grad an Automatisierung vereint. Islaris zeigt, wie die Verifikation von Assembler zu realistischen Modellen von modernen Befehlssatzarchitekturen wie Armv8-A oder RISC-V skaliert werden kann. DimSum entwickelt einen neuen Ansatz für die Verifizierung von Programmen, die aus Komponenten in mehreren Programmiersprachen bestehen (z.B., C und Assembler), wie es oft bei grundlegenden Programmen wie Betriebssystemen der Fall ist. RefinedC und Islaris basieren auf Lithium, eine neue Automatisierungstechnik für Separationslogik, die maschinenüberprüfbare Beweise und Automatisierung verbindet.This research was supported in part by a Google PhD Fellowship, in part by awards from Android Security's ASPIRE program and from Google Research, and in part by a European Research Council (ERC) Consolidator Grant for the project "RustBelt", funded under the European Union’s Horizon 2020 Framework Programme (grant agreement no. 683289)
Temporal datalog with existential quantification
Existential rules, also known as tuple-generating
dependencies (TGDs) or Datalog± rules, are heavily studied in the communities of Knowledge
Representation and Reasoning, Semantic Web,
and Databases, due to their rich modelling capabilities. In this paper we consider TGDs in
the temporal setting, by introducing and studying DatalogMTL∃—an extension of metric temporal Datalog (DatalogMTL) obtained by allowing for existential rules in programs. We show that
DatalogMTL∃
is undecidable even in the restricted
cases of guarded and weakly-acyclic programs. To
address this issue we introduce uniform semantics
which, on the one hand, is well-suited for modelling temporal knowledge as it prevents from unintended value invention and, on the other hand,
provides decidability of reasoning; in particular, it
becomes 2-ExpSpace-complete for weakly-acyclic
programs but remains undecidable for guarded programs. We provide an implementation for the decidable case and demonstrate its practical feasibility. Thus we obtain an expressive, yet decidable,
rule-language and a system which is suitable for
complex temporal reasoning with existential rules
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Growing little learners: enabling trainee teachers to support children's learning in primary science using the outdoors
This thesis explores the ways that outdoor learning is specifically conducive to the support and facilitation of primary science education. Whilst developing practice-led principles for trainee teachers and teachers new to outdoor learning pedagogies, it also challenges the perception of the use of the outdoors being less academic or "risky fun" (Glackin 2016, p.1). The thesis looks at science as being made accessible and meaningful through "getting more from getting out" (Scott and Boyd 2016, p.1). Additionally, by contrast to much of the literature on outdoor science that focuses on professional perceptions and confidence (Waite 2011; Glackin 2016; Harris 2017), this research reports on learning outcomes and the impact on children's attainment.
Across three case study schools, the frameworks from Bloom et al. (1956) and Jelly (1985) were used to support the design and analysis of an outdoor primary science learning matrix. The trainee teachers based in each of the three schools used the matrix to chart and reflect on the ways that children were 'thinking scientifically' through assessing the science learning in the outdoors.
The researcher's analysis of the data generated from interviews with the trainee teachers revealed that when learning science is based in the outdoors, young children are well-placed to demonstrate higher order thinking skills beyond those expected of them within end of Key Stage outcomes (GB.DfE 2013). Specifically, children were seen to develop a set of scientific dispositions involving thinking scientifically, behaving scientifically and questioning scientifically. As such, the trainee teachers used the matrix to foster scientific attitudes such as curiosity, seeking out evidence to support their thought processes and metacognitive aptitudes including reflection and taking ownership of their learning progression.
The researcher's analysis provides exemplification to support trainee teachers, teachers and leaders to understand progression and pitch outdoor learning expectations in ways that enable the setting of challenging individual targets in outdoor science (Ofsted 2011) in line with the end of Key Stage outcomes (GB.DfE 2013)
Assessing land administration systems with their legal frameworks: the case of peri-urban land in Ekiti State, Nigeria
The coexistence of customary and statutory law, tenure, and administration in peri-urban areas of sub-Saharan African (SSA) countries such as Nigeria may cause conflict and tension. An efficient and effective land administration systems (LASs) and legal frameworks are crucial for ensuring pro-poor objectives in land administration. Women, the vulnerable and the poor who are denied access to efficient and effective land administration services tend to experience tenure insecurity. Nigeria is one of the countries with an inefficient and ineffective LASs. The study explores the possibility of hybrid legal systems contributing to tenure insecurity in peri-urban areas of Southwest Nigeria. This study assesses customary and statutory laws and administration systems pertaining to Ekiti State, Nigeria to understand whether there is legal pluralism. A case study of customary and statutory laws, tenure, and administration was carried out using primary and secondary data. The study used three peri-urban cases from Ekiti State, Nigeria (Ikere-Ekiti, Ijero-Ekiti, and Oye-Ekiti) to learn how customary and statutory laws, tenure, and administration operate within the same geographical space. The study adopted Soft System Methodology (SSM), with two analytical frameworks: Responsible Land Management (RLM) and Fit-For-Purpose Land Administration (FFPLA). Moreover, the study used institutional isomorphism theory to determine the conflicting pressure exerted on the customary legal framework, comprising the customary courts and the Customary Court of Appeal of a State (CCAS). The LASs with their legal frameworks were assessed using text-based and empirical approaches. The study findings show weak and deep legal pluralism in LASs. The assessment leads to developing conceptual tools for assessing LASs with their legal frameworks. On the one hand, the conceptual tool for assessing LASs with their legal frameworks is based on the three pillars of human rights, the rule of law, and legal pluralism, taking a constitutional focus. The study findings revealed conflicting pressure exerted on customary courts and the Customary Court Appeal of a State (CCAS). On the other hand, the conceptual tool for measuring land tenure security based on three pillars of jurisdiction, legitimacy, and collaboration. The conceptual tools provide understanding of the influence of the hybrid legal system in LASs in peri-urban areas. The understanding of the influence of hybrid system is based on decentralising land administration activities, local land management, self-determination, and autonomy. The framework also incorporates legal and institutional flexibility. Areas of further research are recommended
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