Periódicos, Publicação

Securing light clients in blockchain with DLCP

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In blockchain, full nodes (FNs) are peers that store and verify entire chains of transactions. In contrast, light clients (LCs) are those with limited resources, and for this reason, they request only block headers from FNs for transaction verification—using protocols like Simple Payment Verification (SPV). In an approach to prevent FN tampering on transaction verification (byzantine fault), LCs request block headers from multiple FNs and compare received responses. One problem with this approach is that an LC must connect to each FN and perform the same cryptographic operations with each one repeatedly, which leads to client-side complexity and slower response. We propose an alternate approach to tackle this issue, in which LCs can encrypt a request for block headers only once, and send that request to a predetermined set of FNs to access, process, and reply back in a single response. Our approach, called Distributed Lightweight Client Protocol (DLCP), enables LCs to verify with little effort if FNs have agreed on a response. From an experimental evaluation, we observed that DLCP provided lower latency and reduced computing and communication overhead in comparison with the existing conventional approach.

Artigos de Conferência, Publicação

Topology Resilience Evaluation and Enhancement in Software Defined Networks

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Software Defined Networks separates the control and forwarding planes, facilitating and flexibilizing the management of networking. However, the interaction between these planes introduces different vulnerabilities to the network, raising new resilience concerns. To assist the planning phase of a Software Defined Network deployment, this paper proposes the application of topological augmentation algorithms to increase the resilience of topologies as indicated by a resilience factor, through optimizations on both control and forwarding planes. In parallel, a brute force controller placement algorithm is applied, for performance comparisons. Tests results demonstrate that the improvement on the test topologies’ resilience characteristics obtained by the joint optimization of both planes surpasses even the most optimal controller placement.

Artigos de Conferência, Publicação

Content Placement Aware Cache Decision: A Caching Policy Based on the Content Replacement Ratio for Information-Centric Network

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Information-Centric Network (ICN) has been an emerging network paradigm for Future Internet based on a host-to-content approach. In this model, both router and users devices are able to store content. One of the key features of ICN is in-network content caching, reducing bandwidth consumption, server load and even enhancing QoE of end-users. ICN behavior is determined by a 3-tuple, which are routing, content insertion and content replacement. Besides, Routing algorithms influence content insertion performance and, which in turn, influences in replacement policies performance. Furthermore, it is proven that content insertion policies influence routing performance and there is no work regarded to analyze the impact of replacement algorithms in content insertion. Therefore this paper proposed a new caching metric called Replacement Ratio and a dynamic content insertion strategy named RatioCache to prove that content replacement, which is strongly bounded to caching system, also influence the caching process. Our results improved up to 110% cache hit ratio, and reduced up to 30% server load and latency up to 10%, thus RatioCache performance shows replacement policies influence caching policies and enhances network performance.

Artigos de Conferência, Publicação

Compartilhamento Seguro de Arquivos de Saúde usando Criptografia Baseada em Atributos e Redes Descentralizadas

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A computação em nuvem possibilita o armazenamento e o compartilhamento de arquivos sob demanda com alta taxa de disponibilidade para aárea da saúde. Contudo, utilizar um provedor de nuvem para armazenar um arquivo de saúde significa confiar a ele a segurança do arquivo. Ao mitigar isso, as abordagens da literatura preocupam-se apenas com a confidencialidade e o controle de acesso, não tratando adequadamente a integridade dos dados. Esse trabalho apresenta o protocolo Decentralized Sharing of Health Records (DSHR), que utiliza criptografia baseada em atributos e redes descentralizadas para o compartilhamento seguro de arquivos de saúde, tratando a confidencialidade, o controle de acesso e a integridade dos arquivos. Uma prova de conceito do DSHR foi implementada e testes de carga foram executados para demonstrar a sua viabilidade prática.

Artigos de Conferência, Publicação

Uma Política de Inserção de Conteúdo baseada na Correlação entre Medidas de Centralidade para Redes Centradas em Conteúdo

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O cache em rede é uma importante característica de Redes Centrada em Conteúdo (RCCs). A escolha dos nodos que armazenarão o conteúdo é um grande desafio e uma boa maneira de fazer isso é através de medidas de centralidade de rede, que descrevem a importância de um nodo, dada uma característica. Entretanto, o grande número de medidas torna a escolha dos nodos ainda mais desafiadora, pois é incerto se uma medida escolhida resultará num alto desempenho em diferentes cenários, dada a sua forte dependência da estrutura topológica. Por conta disso, uma boa alternativa seria considerar a correlação entre elas para selecioná-los. Neste trabalho, propõe-se uma política de inserção de conteúdo baseada na correlação entre medidas de centralidade para selecionaráquelas forte ou mais fortemente correlacionadas para armazenar o conteúdo nos seus nodos correspondentes. Por meio de simulação e utilizando uma boa variedade de topologias nos testes, nossa proposta superou o desempenho das políticas de inserção em termos de taxa de acertos de conteúdo e tempo médio de download.

Artigos de Conferência, Publicação

NECOS Project: Towards Lightweight Slicing of Cloud Federated Infrastructures

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The Novel Enablers for Cloud Slicing (NECOS) project addresses the limitations of current cloud computing infrastructures to respond to the demand for new services, as presented in two use-cases, that will drive the whole execution of the project. The first use-case is focused on Telco service provider and is oriented towards the adoption of cloud computing in their large networks. The second use-case is targeting the use of edge clouds to support devices with low computation and storage capacity. The envisaged solution is based on a new concept, the Lightweight Slice Defined Cloud (LSDC), as an approach that extends the virtualization to all the resources in the involved networks and data centers and provides uniform management with a high-level of orchestration. In this position paper, we discuss the motivation, objectives, architecture, research challenges (and how to overcome them) and initial efforts for the NECOS project.

Artigos de Conferência, Publicação

vSDNEmul: Emulador de Redes Definidas Por Software Usando Contêineres

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Um dos maiores desafios para emuladores de redes SDN são faze-los cada vez mais realistas, versáteis e abertos. Além disso, eles também devem oferecer aplicações reais em seus experimentos, porém, devido a complexidade de integra-los ao emulador estas características não são desenvolvidas. Portanto, para oferecer uma solução mais diversificada que as atuais (ex. Mininet ou vEmulab). Este artigo propõe o vSDNEmul, uma alternativa de emulador de redes SDN onde os nós são baseados em contêineres. Além disso, o artigo também descreve a sua arquitetura e API.

Artigos de Conferência, Publicação

DLCP: Um Protocolo para a Operação Segura de Clientes Leves em Blockchains

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Em blockchains, nodos completos (NCs) são pares que armazenam e verificam todas as transações contidas nos blocos, enquanto clientes leves (CLs) são aqueles que solicitam apenas os cabeçalhos dos blocosá um NC, realizando verificações mais simples. Para lidar com comportamentos maliciosos, a abordagem convencional para garantir o recebimento dos cabeçalhos originais é solicitá-losá múltiplos NCs e comparar as respostas recebidas. Essa abordagem, contudo, requer que um CL estabeleça conexões seguras com cada NC, o que resulta em maior sobrecarga e tempo de resposta. Nesse contexto, esse trabalho propõe o Distributed Lightweight Client Protocol (DLCP), que demanda criptografar uma requisição de cabeçalhos apenas uma vez para um conjunto de NCs, que, por sua vez, retornam umaúnica resposta para o CL. Avaliações preliminares mostraram que o DLCP provê menor latência que a abordagem convencional e reduz a sobrecarga nos CLs.

Artigos de Conferência, Publicação

vSDNBox: Um Hardware Especializado de Baixo Custo Gerenciado via SDN

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Os switches whitebox vêm sendo uma alternativa vantajosa para o plano de dados SDN. Eles permitem tanto a redução nas despesas como também a ampliação dos níveis de heterogeneidade de fabricantes na infraestrutura de rede. Recentes ferramentas possibilitaram que os whiteboxes baseados em software-switches pudessem ampliar seus desempenhos apenas com otimizações feitas via softwares abertos em hardwares genéricos. A partir disso, propõe-se o vSDNBox, uma alternativa de whitebox software-switched para redes definidas por software, capaz de reduzir ainda mais os custos e ampliar o desempenho através de seu gerenciamento e otimizações feitas via software no espaço do usuário. Os resultados obtidos comprovam que a proposta consegue ter um desempenho igual ou aproximado de um whitebox hardwareswitched através de avaliações de vazão e latência.

Artigos de Conferência, Publicação

DLCP: A protocol for securing light client operation in blockchains

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In blockchain, full nodes (FNs) are peers that store and verify entire chains of transactions, and light clients (LCs) are those which outsource chain verification to FNs (as they lack computing resources required to do so). In general, LCs perform simpler verification protocols, e.g. Simple Payment Verification (SPV), by offloading the execution of blockchain operations to FNs. To cope with byzantine faults (like malicious behavior), a current approach for blockchain transaction verification is requiring that LCs outsource their requests to multiple FNs, and compare received results. This approach, however, requires that LCs establish secure connections to each FN, which leads to client-side complexity and slower verification. To tackle this issue, we propose Distributed Lightweight Client Protocol (DLCP), a protocol for secure verification in blockchain. In summary, DLCP requires LCs to encrypt a request once, allowing a pre-determined set of FNs to access and process it. Through DLCP, LCs become able to verify whether FNs have agreed on the operation outcome. From some preliminary evaluation, we observed that DLCP decreased computing and communication overhead in LCs, while providing lower latency.

Artigos de Conferência, Publicação

Topology resilience enhancement for software defined networks

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Software Defined Networks is a paradigm that flexibilizes the management of networking, separating the control and forwarding planes. This separation introduces new concerns towards the resilience of the network, which now presents different vulnerabilities related to the interaction between these planes. A resilience factor for Software Defined Networks is proposed, using multiple metrics to analyze intrinsic features of its architecture, serving as an indication for its resilience. Beyond that, topological augmentation algorithms are employed to increase the resilience of test topologies, as indicated by the proposed factor. Tests results demonstrate an improvement of the topologies’ resilience characteristics.

Artigos de Conferência, Publicação

FI-MApp: a web application for managing FI-WARE environments in internet of things

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The FI-WARE project aims to create a core platform for the Future Internet. However, such a platform has failed to promote the centralization of its services, since it did not offer a unified development framework. In addition, it demands a great effort to use the platform, due to extensive, disordered and scattered documentation. In this context, the present work explored the FI-WARE service for enabling the Internet of Things (IoT). The main goal was to develop a Web application for an integrated visualization and management of the resources offered by FI-WARE IoT enabling services. Called FI-MApp, the proposed Web application acts as a bridge (middleware) between the FI-WARE IoT service and its managers. FI-MApp is shown as suitable solution in this scenario because the FI-WARE APIs have already been implemented following the RESTful Web service architecture. Through its simple and intuitive user interface, the FI-MApp Web application make it easy for both managing and visualizing FI-WARE IoT environments from different parts of the world by offering features, such as registering new IoT devices and data collection from both real and virtual sensors.

Artigos de Conferência, Publicação

Securing light clients in blockchain with DLCP

/

In blockchain, full nodes (FNs) are peers that store and verify entire chains of transactions. In contrast, light clients (LCs) are those with limited resources, and for this reason, they request only block headers from FNs for transac- tion verification—using protocols like Simple Payment Verification (SPV). In an approach to prevent FN tampering on transaction verification (byzantine fault), LCs request block headers from multiple FNs and compare received responses. One problem with this approach is that an LC must connect to each FN and per- form the same cryptographic operations with each one repeatedly, which leads to client-side complexity and slower response. We propose an alternate approach to tackle this issue, in which LCs can encrypt a request for block headers only once, and send that request to a predetermined set of FNs to access, process, and reply back in a single response. Our approach, called Distributed Lightweight Client Protocol (DLCP), enables LCs to verify with little effort if FNs have agreed on a response. From an experimental evaluation, we observed that DLCP pro- vided lower latency and reduced computing and communication overhead in comparison with the existing conventional approach.