Luiz Albini - Profile on Academia.edu (original) (raw)

Papers by Luiz Albini

TRUMIT—Trust Manager for IoT

Smart innovation, systems and technologies, Dec 16, 2020

Journal of Network and Computer Applications, Aug 1, 2014

Mobile Ad Hoc Networks are a very fascinating research topic, mainly due to their self-organized ... more Mobile Ad Hoc Networks are a very fascinating research topic, mainly due to their self-organized and autonomous nature and the absence of pre-established communication infrastructure requirements. In several scenarios, such as conference meetings, rescue operations and battlefields, these networks are extremely attractive. However, the particularities of MANETs, such as their dynamic topology, lack of infrastructure and decentralized characteristics make the implementation of complex and flexible applications difficult. To enable the deployment of these applications and extend supporting services, several middleware solutions for MANETs can be found in the literature. Middleware is a software layer typically between the operating system and the distributed applications, transparently providing interoperability, distribution of functionality, scalability, load balancing and fault tolerance for the applications. This article surveys all middleware solutions for MANETs, describing their operations, presenting a comparison of available functionalities and discussing their qualities and limitations, focused on services as group support, resource discovery, location, and security. Proposed middlewares are subdivided into five categories: tuple space-based, P2P-based, context-based, cross-layer and application-oriented solutions. The classification considered their design strategy and communication model characteristics. Also, all presented middleware solution are depicted on figures, which facilitates the comparison between them. Further, at the end of each category, a summary table is available, making the overall analysis easier. Finally, the article identifies open issues and researches directions on the design of middleware solutions for MANETs.

Esquemas de gerenciamento de chaves para Redes �� Móveis (�� -MANETs) pre... more Esquemas de gerenciamento de chaves para Redes �� Móveis (�� -MANETs) precisam funcionar em ambientes com topologia dinâmica e serem auto-organizáveis e descentralizados . Além disso, devem satisfazer alguns requisitos como ]: não ter um ponto único de falha; ser tolerante ao comprometimento ds nós; ser capaz de revogar as chaves dos nós comprometidos e atualizar as chaves dos nós não-comprometidos; ser eficiente quanto ao armazenamento, o processamento e a comunicac ¸ão.

Fully Distributed Public Key Management through Digital Signature Chains for Delay and Disrupt Tolerant Networks

Security solutions are not easily adapted to the DTN paradigm, for example, traditional key manag... more Security solutions are not easily adapted to the DTN paradigm, for example, traditional key management solutions cannot be applied in such environments. A key management scheme for DTNs must consider the dynamic topology, be self-organized and distributed and be effective in the presence of intermittent connections. There are just a few key management scheme for DTNs. Nevertheless, all of them have serious issues. They generate a huge overhead, have a single point of failure, are centralized or do not provide any security against very simple attacks. This work introduces a new key management scheme for DTNs based on chains of digital signatures (DSC-KM - Digital Signature Chains Key Management Scheme). It is decentralized, fully distributed, and does not have a single point of failure. It allows nodes to leave and joint the network at any time, works in the presence of intermittent connections, has a very small communication and memory overhead. It is based on chains of digital signatures and on a very simple chain exchange mechanism. According to simulation results, it is able to correctly and securely disseminate all certificates through the network in a short period, while maintaining the size of the chains very small. Moreover, it is able to resist to several attacks to the key management infrastructure.

Simulation is one of the main tools used to analyze new proposals in the Network-on-Chip (NoC) fi... more Simulation is one of the main tools used to analyze new proposals in the Network-on-Chip (NoC) field. Among these simulators for analyzing and testing new ideas in NoC architectures, the Noxim simulator stands out, being used by many researchers due to the wireless support and open-source availability. An important issue at the simulation phase is the choice of workload, as it may affect testing the system and its features. The correct workload can lead to rapid and efficient system development, while the wrong one may compromise the entire system evaluation. To ensure a more realistic simulation, simulators usually relies on real workloads by using a tracedriven approach. Although Noxim provides a simple support for input traces, it is very limited to a general behavior of the system, accepting only a generic injection rate parameter over time. We propose in this paper an extension of the Noxim simulator to address these issues. This extension enables Noxim to easily receive and process a real workload traces from real applications, considering each message sent by each processing element over the NoC. This extension was demonstrated and evaluated using the NAS-NPB workload. Our results show that Noxim still generating trusty results when using our trace extension.

Design Automation for Embedded Systems, Jan 5, 2019

Simulation is one of the main tools used to analyze and test new proposals in the Network-on-Chip... more Simulation is one of the main tools used to analyze and test new proposals in the Network-on-Chip field. Several simulators can be found in the literature, among them the Noxim simulator stands out. It is being used by many researchers due to the wireless support and open-source availability. An important issue at the simulation phase is the choice of workload, as it may affect testing the system and its features. The correct workload can lead to rapid and efficient system development, while the wrong one may compromise the entire system evaluation. To ensure a more realistic simulation, simulators usually relies on real workloads by using a trace-driven approach. Although Noxim provides a simple support for input traces, it is very limited to a general behavior of the system, accepting only a generic injection rate parameter over time. Another important part of the simulator is the ability to consider the Processing Elements processing time. We propose in this paper an extension of the Noxim simulator to address these issues. Consequently, results are more realistic and may be possible to predict the total execution time very accurately. This extension is demonstrated and evaluated using the NAS-NPB workload. Keywords Network-on-Chip • Simulation • Processing time • Trace 1 Introduction Network-on-Chip (NoC) [7] is the current interconnection paradigm to design all large-scale chips. It is scalable and can be adapted to several computational paradigms and applicable to This work was partially supported by CNPq and CAPES.

Journal of Information and Data Management, Sep 12, 2022

Distributed database systems store and manipulate data on multiple machines. In these systems, th... more Distributed database systems store and manipulate data on multiple machines. In these systems, the processing cost of query operations is mainly impacted by the data access latency between machines over the network. With recent technology advances in programmable network devices, the network switches provide new opportunities for dynamically managing the network topology, enabling the data processing on these devices with the same network throughput. In this paper, we explore the programmable network switches in query processing, evaluating the processing performance of a cost model in executing the hash join operation. We assume the storage of the hash table built from outer relation and the materialization of the join probing are made in switches using advanced matching techniques similar to package inspections enabled by Ternary Content-Addressable Memories (TCAM) or SRAM via hashing. Our results show that processing the hash join operation using network switches achieved the best results compared to traditional servers, with an average time reduction of 91.82% (Query-10 from TPC-H) and 96.52% (Query-11 from TPC-H).

Supporting Confidentiality and Integrity on V2V Communications

Nefarious users or attackers may target vehicular networks for malicious objectives, such as unla... more Nefarious users or attackers may target vehicular networks for malicious objectives, such as unlawfully collecting data or tampering with communications. There are several coun-termeasures to these challenges in the literature; however, they are tailored to a specific scenario with infrastructure or focused on new routing protocols. To mitigate the effects of malicious attacks on vehicular network communications, this work proposes the development of a group-based security framework, which is independent of the routing protocol with vehicular-to-vehicular communication and capable of forming groups with trusted nodes and adding security to vehicular network communications between group members. This framework should be able to work in connected network settings while ensuring the security and integrity of the information transferred over it. To employ a hybrid cryptography system, the framework needs to have a trust management method for forming groups and establishing group-shared keys in a decentralized manner.

The query processing cost in distributed database systems is directly associated with transferrin... more The query processing cost in distributed database systems is directly associated with transferring data cost over the network. The Software-Defined Wide-Area Network (SD-WAN) allows (re)program network devices via software. The programmability of this architecture provides new possibilities for dynamically manage the network topology, also enabling the data processing on these devices. This paper presents an evaluation of the distributed processing of the hash join operation to the database and network devices, using an cost model. Our results show that processing the hash join operation using network switches could achieve competing results compared to traditional servers with similar data traffic.

Reducing Hadoop 3.x energy consumption through Energy Efficient Ethernet

Energy consumption is one of the major challenges on the big data processing infrastructure. The ... more Energy consumption is one of the major challenges on the big data processing infrastructure. The energy expenses are even higher than hardware, accounting for 75% of the total cost of nowadays data centers. Narrowing, approximately 30% of all data center energy is consumed by the network switches. Energy Efficient Ethernet is a recent standard aiming at reduce network power consumption, notwithstanding the current practice in industry is to disable it in production use, since it can cause network overloads and performance loss. This paper provides an overview on how Apache Hadoop 3.x, the current version, behaves with Energy Efficient Ethernet enabled for links from 1GbE up to 400GbE links. Presented results show that there is significant energy savings with little or no performance loss for connections up to 40GbE. Nevertheless, connections of 100GbE and 400GbE present significant performance losses due to link wake up to single transmissions. These results demonstrate the effectiveness of EEE and indicate a possible research field on the ultra high speed networks energy efficiency.

Journal of computer and communications, 2020

VANET security is an evolving topic in mobile networks, as providing a secure layer of communicat... more VANET security is an evolving topic in mobile networks, as providing a secure layer of communications in such a dynamic and fast network is a challenge. The work presented in this article was conducted in order to verify and evaluate the feasibility of applying group broadcast cryptography to the VANET environment, as an attempt to gain performance by decreasing the number of messages in the wireless network. Group broadcast is a symmetric/asymmetric hybrid cryptography method, aiming to merge the best of the two approaches without their major drawbacks. Simulations were set-up and run using the ONE simulator, comparing the usage of the three different cryptography approaches for VANETs. Results consider the number of connections, the number messages and the number of revocation messages per day. The resulting data promises that group broadcast encryption can be used to simplify the encrypting phase, reduce required storage and significantly decrease the number of messages in the network.

Anais do XVIII Simpósio Brasileiro de Sistemas Colaborativos (SBSC 2023)

Este artigo apresenta um Mapeamento Sistemático Multivocal que visa identificar aplicativos desen... more Este artigo apresenta um Mapeamento Sistemático Multivocal que visa identificar aplicativos desenvolvidos para o contexto da pandemia de Covid-19, bem como os métodos de rastreamento de contatos utilizados por eles e suas principais funcionalidades. O MLM foi conduzido na literatura branca e cinza, totalizando 73 aplicações, sendo 70 aplicativos móveis e três protocolos. Os resultados apontam que os métodos mais utilizados são: bluetooth para rastreamento de contato; notificação pelo usuário para identificar casos positivos; troca de ID temporária para o estabelecimento da rede de contato; e notificação de exposição pelo próprio aplicativo.

CEIFA: A multi-level anomaly detector for smart farming

Computers and Electronics in Agriculture

An Evaluation about Routing Protocols in Delay-Tolerant Networks (DTNs) to apply Quality of Context (QoC)

Proceedings of the 14th CONTECSI International Conference on Information Systems and Technology Management, 2017

Ontology using to represent a systematic literature review about Quality of Context

Anais do Computer on the Beach, 2018

O roteamento em redes Delay-Tolerant Networks(DTN) e um desafio devido aos frequentes e longos pe... more O roteamento em redes Delay-Tolerant Networks(DTN) e um desafio devido aos frequentes e longos periodos de nao conectividade. O comportamento da rede depende de uma variedade de parâmetros que mudam ao longo do tempo e geram desafios importantes na comunicacao e no roteamento. Varios protocolos de roteamento em DTN podem ser encontrados na literatura, baseados em estrategias que vao desde inundacoes ate abordagens oportunistas. Todos esses protocolos tem pontos fortes e fracos dependendo do cenario de uso. Neste estudo, foram avaliados os protocolos Epidemic, PRoPHET, Spray-and-Wait e RAPID atraves de simulacoes, a fim de verificar seus desempenhos, considerando alguns parâmetros criticos.

Array, 2020

Stent loss during PCI occurs infrequently in the current era (incidence 0.32%) and is more likely... more Stent loss during PCI occurs infrequently in the current era (incidence 0.32%) and is more likely to occur in tortuous and calcified coronary arteries. Lost stents can be successfully retrieved in the majority of cases using a variety of retrieval techniques like low pressure balloon inflation technique, small balloon technique, double wire technique and loop snare technique. Stent loss is associated with an increased risk of complications, such as significant bleeding and need for emergency coronary artery bypass graft surgery. Stents lost in small branches can be left. If stent is not retrieved it may be deployed or crushed.

International Journal of Wireless Information Networks, 2017

Delay and Disruption Tolerant Networks are made up of mobile wireless nodes which may experience ... more Delay and Disruption Tolerant Networks are made up of mobile wireless nodes which may experience major message delivery restrictions. Such restrictions are the result of intermittent connectivity and scattered topology. Within these networks, messages can be detained for long periods of time or never be delivered. Existing solutions that purport improved message delivery rates modify routing protocols to perform integrity verification with each hop, resulting in routing overhead and, very often, unnecessary processing costs. This article proposes a scheme, named EMCOD, which decreases message delivery delay, while minimally increasing the processing overheads. To achieve this, EMCOD uses data encoding and interleaving to create messages. The original data is reassembled from some of the messages received, without the need to wait for all messages to be received. In scenarios subject to long delays and/or significant packet loss rates, it is possible to reduce original data recovery times by more than 50%. The processing overhead resulting from the encoding procedures is offset by the data recovery capabilities, which effectively decreases network overheads by more than 60%, in the same scenarios. EMCOD modifies the Bundle Layer, without interfering with the remaining layers, making it possible to route the messages through nodes that do not implement the proposed scheme.

International Journal of English Linguistics, 2017

This study investigates the effects of perceptual training on Brazilian English language learners... more This study investigates the effects of perceptual training on Brazilian English language learners’ ability to acquire preantepenultimate stress, or stress on the fourth to last syllable. Since preantepenultimate stress assignment is infrequent in Brazilian Portuguese (BP), it was initially hypothesized that BP speakers would store few examples of this pattern. The training was performed in five sessions and included stress identification tasks followed by immediate feedback. Results confirm the training significantly improved study participants’ perception and production of preantepenultimate syllable stress assignment. Furthermore, participants generalized acquired production patterns to unfamiliar words and retained these patterns for two months after training concluded. With frequent perceptual training, it is believed BP speakers could create a new category of English words with preantepenultimate syllable stress. This study demonstrates that perception training, typically used ...

Trust evaluation is an essential service to ensure reliability on security relationships on netwo... more Trust evaluation is an essential service to ensure reliability on security relationships on networks, including Mobile Ad Hoc Networks (MANETs). However, the implementation of an effective trust evaluation service is very difficult in these networks, due to their dynamic characteristics. Though many trust evaluation services for MANETs can be found in the literature, they were not designed considering malicious attacks or were not evaluated under these attacks. This work presents TRUE, a distributed trust evaluation service for MANETs which creates a self-organized context-based trust network. To estimate the trustworthiness of other nodes, nodes form trust chains based on behavior evidences maintained within the context-based trust network. Periodically, nodes exchange trust information with the neighbors, providing an efficient method to disseminate these information through the network. Simulation results show that TRUE is very efficient on gathering evidences to build the trust networks, maintaining a small communication and memory overhead. Further, it is the first trust evaluation scheme evaluated under bad mouthing and newcomers attacks and it maintains its effectiveness in such scenarios.