Configurable Private Querying: Lookup and Partial Matching under Homomorphic Encryption

The ability to query a database privately is nowadays ubiquitous via an encrypted channel. With the advent of homomorphic encryption, there is a want to expand the notion of privacy in this context to querying privately on the database with the database learning as little to no information of the query data or its result. The ability to compute the intersection from at least two parties’ sets that are kept private only to themselves is known as private set intersection (PSI) and should be considered a fundamental operation in several homomorphic computation scenarios to do useful work; not least for the ability to implement queries on a database. We outline in this paper a novel highly configurable PSI structure to be used in private querying providing the possibility that even the exact query itself can be protected from the database if required. As well as complex database lookups, there is also a more complex partial matching. The outline of the system design is discussed and we report preliminary results on some of the fundamental operations. We demonstrate that this technology is emerging as a viable given response to lookup queries and partially matching on an encrypted database with over a million entries in approximately 9 minutes

SafeSpark: a secure data analytics platform using cryptographic techniques and trusted hardware

Dissertação de mestrado em Informatics EngineeringNowadays, most companies resort to data analytics frameworks to extract value from the increasing amounts of digital information. These systems give substantial competitive ad vantages to companies since they allow to support situations such as possible marketing decisions or predict user behaviors. Therefore, organizations tend to leverage the cloud to store and perform analytics over the data. Database services in the cloud present significant advantages as a high level of efficiency and flexibility, and the reduction of costs inherent to the maintenance and management of private infrastructures. The problem is that these services are often a target for malicious attacks, which means that sensitive and private personal information can be compromised. The current secure analytical processing solutions use a limited set of cryptographic techniques or technologies, which makes it impossible to explore different trade-offs of performance, security, and functionality requirements for different applications. Moreover, these systems also do not explore the combination of multiple cryptographic techniques and trusted hardware to protect sensitive data. The work presented here addresses this challenge, by using cryptographic schemes and the Intel SGX technology to protect confidential information, ensuring a practical solution which can be adapted to applications with different requirements. In detail, this dissertation begins by exposing a baseline study about cryptographic schemes and the Intel SGX tech nology, followed by the state-of-the-art revision about secure data analytics frameworks. A new solution based on the Apache Spark framework, called SafeSpark, is proposed. It provides a modular and extensible architecture and prototype, which allows protecting in formation and processing analytical queries over encrypted data, using three cryptographic schemes and the SGX technology. We validated the prototype with an experimental evalu ation, where we analyze the performance costs of the solution and also its resource usage. For this purpose, we use the TPC-DS benchmark to evaluate the proposed solution, and the results show that it is possible to perform analytical processing on protected data with a performance impact between 1.13x and 4.1x.Atualmente, um grande número de empresas recorre a ferramentas de análise de dados para extrair valor da quantidade crescente de informações digitais que são geradas. Estes sistemas apresentam consideráveis vantagens competitivas para as empresas, uma vez que permitem suportar situações como melhores decisões de marketing, ou até mesmo prever o comportamento dos seus clientes. Neste sentido, estas organizações tendem a recorrer a serviços de bases de dados na nuvem para armazenar e processar informação, uma vez que estas apresentam vantagens significativas como alto nível de eficiência e flexibilidade, bem como a redução de custos inerentes a manter e gerir uma infraestrutura privada. No entanto, estes serviços são frequentemente alvo de ataques maliciosos, o que leva a que informações pessoais privadas possam estar comprometidas. As soluções atuais de processamento analítico seguro utilizam um conjunto limitado de técnicas criptográficas ou tecnologias, o que impossibilita o balanceamento de diferentes compromissos entre performance, segurança e funcionalidade para diferentes aplicações. Ainda, estes sistemas não permitem explorar a simultânea utilização de técnicas criptográficas e de hardware confiável para proteger informação sensível. O trabalho apresentado nesta dissertação tem como objetivo responder a este desafio, utilizando esquemas criptográficos e a tecnologia Intel SGX para proteger informação confidencial, garantindo unia solução prática que pode ser adaptada a aplicações com diferentes requisitos. Em detalhe, este documento começa por expor um estudo de base sobre esquemas criptográficos e sobre a tecnologia SGX, seguido de uma revisão do estado de arte atual sobre ferramentas de processamento analítico seguro. Uma nova solução baseada na plataforma Apache Spark, chamada SafeSpark, é proposta. Esta providencia uma arquitetura modular e extensível, bem como um protótipo, que possibilita proteger informação e executar interrogações analíticas sobre dados cifrados, utilizando três esquemas criptográficos e a tecnologia Intel SGX. O protótipo foi validado com uma avaliação experimental, onde analisamos a penalização de desempenho da solução, bem como a sua utilização de recursos computacionais. Com este propósito, foi utilizada a plataforma de avaliação TPC-DS para avaliar a solução proposta, e os resultados mostram que é possível executar processamento analítico sobre dados protegidos, apresentando um impacto no desempenho entre 1.13x e 4.1x.This work was partially funded by FCT - Fundação para a Ciência e a Tecnologia, I.P., (Portuguese Foundation for Science and Technology) within project UID/EEA/50014/2019

On the cyber security issues of the internet infrastructure

The Internet network has received huge attentions by the research community. At a first glance, the network optimization and scalability issues dominate the efforts of researchers and vendors. Many results have been obtained in the last decades: the Internet’s architecture is optimized to be cheap, robust and ubiquitous. In contrast, such a network has never been perfectly secure. During all its evolution, the security threats of the Internet persist as a transversal and endless topic. Nowadays, the Internet network hosts a multitude of mission critical activities. The electronic voting systems and financial services are carried out through it. Governmental institutions, financial and business organizations depend on the performance and the security of the Internet. This role confers to the Internet network a critical characterization. At the same time, the Internet network is a vector of malicious activities, like Denial of Service attacks; many reports of attacks can be found in both academic outcomes and daily news. In order to mitigate this wide range of issues, many research efforts have been carried out in the past decades; unfortunately, the complex architecture and the scale of the Internet make hard the evaluation and the adoption of such proposals. In order to improve the security of the Internet, the research community can benefit from sharing real network data. Unfortunately, privacy and security concerns inhibit the release of these data: its suffices to imagine the big amount of private information (e.g., political preferences or religious belief) it is possible to get while reading the Internet packets exchanged between users and web services. This scenario motivates my research, and represents the context of this dissertation which contributes to the analysis of the security issues of the Internet infrastructures and describes relevant security proposals. In particular, the main outcomes described in this dissertation are: • the definition of a secure routing protocol for the Internet network able to provide cryptographic guarantees against false route announcement and invalid path attack; • the definition of a new obfuscation technique that allow the research community to publicly release their real network flows with formal guarantees of security and privacy; • the evidence of a new kind of leakage of sensitive informations obtained hacking the models used by sundry Machine Learning Algorithms

An Agent-Based Intrusion Detection System for Local Area Networks

Since it is impossible to predict and identify all the vulnerabilities of a network beforehand, and penetration into a system by malicious intruders cannot always be prevented, intrusion detection systems (IDSs) are essential entities to ensure the security of a networked system. To be effective in carrying out their functions, the IDSs need to be accurate, adaptive, and extensible. Given these stringent requirements and the high level of vulnerabilities of the current days' networks, the design of an IDS has become a very challenging task. Although, an extensive research has been done on intrusion detection in a distributed environment, distributed IDSs suffer from a number of drawbacks e.g., high rates of false positives, low detection efficiency etc. In this paper, the design of a distributed IDS is proposed that consists of a group of autonomous and cooperating agents. In addition to its ability to detect attacks, the system is capable of identifying and isolating compromised nodes in the network thereby introducing fault-tolerance in its operations. The experiments conducted on the system have shown that it has a high detection efficiency and low false positives compared to some of the currently existing systems.Comment: 13 pages, 5 figures, 2 table

Attack graph approach to dynamic network vulnerability analysis and countermeasures

A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the degree of Doctor of PhilosophyIt is widely accepted that modern computer networks (often presented as a heterogeneous collection of functioning organisations, applications, software, and hardware) contain vulnerabilities. This research proposes a new methodology to compute a dynamic severity cost for each state. Here a state refers to the behaviour of a system during an attack; an example of a state is where an attacker could influence the information on an application to alter the credentials. This is performed by utilising a modified variant of the Common Vulnerability Scoring System (CVSS), referred to as a Dynamic Vulnerability Scoring System (DVSS). This calculates scores of intrinsic, time-based, and ecological metrics by combining related sub-scores and modelling the problem’s parameters into a mathematical framework to develop a unique severity cost. The individual static nature of CVSS affects the scoring value, so the author has adapted a novel model to produce a DVSS metric that is more precise and efficient. In this approach, different parameters are used to compute the final scores determined from a number of parameters including network architecture, device setting, and the impact of vulnerability interactions. An attack graph (AG) is a security model representing the chains of vulnerability exploits in a network. A number of researchers have acknowledged the attack graph visual complexity and a lack of in-depth understanding. Current attack graph tools are constrained to only limited attributes or even rely on hand-generated input. The automatic formation of vulnerability information has been troublesome and vulnerability descriptions are frequently created by hand, or based on limited data. The network architectures and configurations along with the interactions between the individual vulnerabilities are considered in the method of computing the Cost using the DVSS and a dynamic cost-centric framework. A new methodology was built up to present an attack graph with a dynamic cost metric based on DVSS and also a novel methodology to estimate and represent the cost-centric approach for each host’ states was followed out. A framework is carried out on a test network, using the Nessus scanner to detect known vulnerabilities, implement these results and to build and represent the dynamic cost centric attack graph using ranking algorithms (in a standardised fashion to Mehta et al. 2006 and Kijsanayothin, 2010). However, instead of using vulnerabilities for each host, a CostRank Markov Model has developed utilising a novel cost-centric approach, thereby reducing the complexity in the attack graph and reducing the problem of visibility. An analogous parallel algorithm is developed to implement CostRank. The reason for developing a parallel CostRank Algorithm is to expedite the states ranking calculations for the increasing number of hosts and/or vulnerabilities. In the same way, the author intends to secure large scale networks that require fast and reliable computing to calculate the ranking of enormous graphs with thousands of vertices (states) and millions of arcs (representing an action to move from one state to another). In this proposed approach, the focus on a parallel CostRank computational architecture to appraise the enhancement in CostRank calculations and scalability of of the algorithm. In particular, a partitioning of input data, graph files and ranking vectors with a load balancing technique can enhance the performance and scalability of CostRank computations in parallel. A practical model of analogous CostRank parallel calculation is undertaken, resulting in a substantial decrease in calculations communication levels and in iteration time. The results are presented in an analytical approach in terms of scalability, efficiency, memory usage, speed up and input/output rates. Finally, a countermeasures model is developed to protect against network attacks by using a Dynamic Countermeasures Attack Tree (DCAT). The following scheme is used to build DCAT tree (i) using scalable parallel CostRank Algorithm to determine the critical asset, that system administrators need to protect; (ii) Track the Nessus scanner to determine the vulnerabilities associated with the asset using the dynamic cost centric framework and DVSS; (iii) Check out all published mitigations for all vulnerabilities. (iv) Assess how well the security solution mitigates those risks; (v) Assess DCAT algorithm in terms of effective security cost, probability and cost/benefit analysis to reduce the total impact of a specific vulnerability

Foundations of secure computation

Issued as Workshop proceedings and Final report, Project no. G-36-61