Indexing Information for Data Forensics

We introduce novel techniques for organizing the indexing structures of how data is stored so that alterations from an original version can be detected and the changed values specifically identified. We give forensic constructions for several fundamental data structures, including arrays, linked lists, binary search trees, skip lists, and hash tables. Some of our constructions are based on a new reduced-randomness construction for nonadaptive combinatorial group testing

Query Racing: Fast Completeness Certification of Query Results

International audienceWe present a general and effective method to certify completeness of query results on relational tables stored in an untrusted DBMS. Our main contribution is the concept of "Query Race": we split up a general query into several single attribute queries, and exploit concurrency and speed to bind the complexity to the fastest of them. Our method supports selection queries with general composition of conjunctive and disjunctive order-based conditions on different attributes at the same time. To achieve our results, we require neither previous knowledge of queries nor specific support by the DBMS. We validate our approach with experimental results performed on a prototypical implementation

Improving Authenticated Dynamic Dictionaries, with Applications to Cryptocurrencies

We improve the design and implementation of two-party and three-party authenticated dynamic dictionaries and apply these dictionaries to cryptocurrency ledgers. A public ledger (blockchain) in a cryptocurrency needs to be easily verifiable. However, maintaining a data structure of all account balances, in order to verify whether a transaction is valid, can be quite burdensome: a verifier who does not have the large amount of RAM required for the data structure will perform slowly because of the need to continually access secondary storage. We demonstrate experimentally that authenticated dynamic dictionaries can considerably reduce verifier load. On the other hand, per-transaction proofs generated by authenticated dictionaries increase the size of the blockchain, which motivates us to find a solution with most compact proofs. Our improvements to the design of authenticated dictionaries reduce proof size and speed up verification by 1.4-2.5 times, making them better suited for the cryptocurrency application. We further show that proofs for multiple transactions in a single block can compressed together, reducing their total length by approximately an additional factor of 2. We simulate blockchain verification, and show that our verifier can be about 20 times faster than a disk-bound verifier under a realistic transaction load

Hypatiamat - I want to solve questions about...

Dissertação de mestrado em Informatics EngineeringHypatiamat is a Portuguese project comprised of several applications that aim to develop the Math skills of students from the 1st through 9th grades (Basic Education). The ingraining of mental calculation strategies, numbering systems, and logical operations lead to a better success rate in this subject in later years. One of the project’s components is the online platform (https://www.hypatiamat.com), which aims to foster autonomous learning through more interactive practices due to the current ease of technological access in this age group, by trying to appropriate teaching to everyday life. Several tools are made available, such as videos, tutorials, explanations, questions, etc. on various Math topics that students can easily access at any time. Teachers that aim to enhance their students’ learning process using this digital approach can exercise it in multiple applications provided by the platform, where the interactions are carried out and controlled through these means. The monolithic architecture (written in PHP) has received contributions from multiple developers over the years in order to address the scalability issues introduced with this platform’s growing popularity, which thus far demanded manual efforts for maintenance and content insertion. As such, there has been an incremental process of modernization, turning the various constituent applications into distinct microservices. "I Want to Solve Questions About..." is one of these applications where students are provided with a large selection of questions in the form of mini-games (multiple choice, true or false, ...), regarding the themes mentioned above. The first objective of the dissertation is to develop a back-office that allows the teachers in charge of the project to manage existing questions as well as add new ones for the students, since the current process requires updating the database manually. The second one is the modernization of the application’s interface at the technological level, by making use of adequate frameworks and programming languages and at the user level, by making an effort to maintain the intuitive workflow that led to its popularity but with a modernized design, in order to be consistent with other online tools.O Hypatiamat é um projeto português constituído por várias aplicações que visa desenvolver as aptidões, na disciplina de Matemática, de alunos do 1º ao 9º ano de escolaridade (Educação Básica). O enraizamento de estratégias de cálculo mental, sistemas de numeração e operações lógicas originam uma melhor taxa de sucesso nesta disciplina em anos posteriores. Uma das componentes deste projeto é a plataforma online (https://www.hypatiamat.com), cujo propósito é fomentar a aprendizagem autónoma através de práticas mais interativas, devido à facilidade de acesso tecnológico atual desta faixa etária, tentando apropriar o ensino ao quotidiano. São disponibilizadas várias ferramentas, tais como vídeos, tutoriais, explicações, questões, etc sobre os vários temas da Matemática (Ensino Básico) que os alunos podem facilmente aceder a qualquer momento. Professores que pretendam enriquecer a aprendizagem dos seus alunos com esta metodologia digital podem exercê-lo nas várias aplicações que a plataforma disponibiliza, onde a interação é realizada e controlada através destes meios. A arquitetura monolítica (escrita em PHP) tem recebido contribuições de vários desenvolvedores ao longo dos anos de modo a colmatar os problemas de escalabilidade introduzidos com a popularidade crescente desta plataforma, que até agora exigia esforço manual para manutenção e inserção de conteúdo. Assim, tem existido um processo incremental de modernização, tornando as várias aplicações constituintes em microsserviços distintos. A "Quero resolver questões de..." é uma destas aplicações, onde são disponibilizadas aos alunos várias questões, sob a forma de mini-jogos (escolha múltipla, verdadeiro ou falso, ...), relativas aos temas mencionados anteriormente. O primeiro objetivo da dissertação é o desenvolvimento de um backoffice que permita aos professores responsáveis gerirem as questões existentes assim como adicionarem novas para os alunos, visto que o processo atual obriga a atualização manual na base de dados. O segundo é a modernização da interface da aplicação ao nível: tecnológico, utilizando frameworks e linguagens de programação adequadas ao problema; do utilizador, de modo a manter o fluxo intuitivo que gerou a sua popularidade mas tendo em conta um design mais atualizado para manter a consistência com outras ferramentas online

Authentication/authorization issues and fulltext document migration for the CERN Document Server

This thesis describes a master degree project, ending studies at Università degli Studi di Milano-Bicocca of Computer Science, Milano. This work has been realized at the European Organization of Nuclear Research (CERN), in Geneva. The aim of the project was to enhance CDS Invenio, a digital library software developed by CERN, in the authentication/authorization area, to develop an automatic migration tool for moving documents from the legacy architecture and to develop an extension to Python in C for solving indexing time issues

IU-Advise: A Web Based Advising Tool For Academic Advisors and Students

Thesis (M.S.) -- Indiana University South Bend, 2009.Academic advising is an important activity of an academic institution. It guides the students to explore potential careers, academic disciplines and opportunities in the college environment. An accurate and full featured advising system can be an effective tool to both students and faculty advisors. The dynamic nature of academic programs, especially in regards to changes in the general education and other degree requirements, poses a continuous challenge to faculty advisors to remain up-to-date. The goal of this thesis is to implement a web-based advising system which facilitates academic advisors in their efforts to providing quality, accurate and consistent advising services to their students. The proposed system was implemented using a set of open source software packages to create a low cost, flexible, and customizable system