Raphael Machado

dblp:83/1163 · also Raphael C. S. Machado, Raphael Carlos Santos Machado · DBLP profile ↗
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39ranked-venue papers
9as first author
3since 2021 · last 2023
0000-0003-3339-9735ORCID · corroborated

Domains — the database's venue-derived domains; a paper can count in several

Theory of computation · 22 · 6 first-author · 1 since 2021Applied, interdisciplinary, general and emerging computing · 7Security and privacy · 5 · 2 first-author · 1 since 2021Computer networks · 2 · 1 first-authorSystems, architecture and hardware · 1Software engineering, systems software and programming languages · 1
YearPublicationVenuePosition
2023 Systematic Literature Review of Threat Modeling Concepts
Pedro A. Lohmann, Carlos Albuquerque, Raphael Machado
ICISSP3
2022 Crowdsourcing and monetization as a strategy to reduce vehicular greenhouse gases emissions
abstract
This paper presents a strategy to estimate and control vehicular greenhouse emissions by combining crowdsourcing and monetization. We assume that vehicle manufacturers must accomplish emission limits and can demonstrate it by collecting carbon credits which consist of emissions estimates received directly from vehicles’ onboard computers. Manufacturers then can trade these credits in a blockchain-based monetization platform, feeding a self-sustainable strategy that motivates more drivers to participate in crowdsourcing. We discuss the practical aspects and challenges of implementing this strategy and also implement a prototype consisting of a smartphone app, a cloud-based system to compute emissions estimates, and a blockchain-based platform to perform monetization. Experiments performed in two different scenarios attest to our idea’s feasibility.
Wilson S. Melo Jr., Paulo R. M. Nascimento, Kauã Gomes, Malkai Oliveira, Raphael Machado
VTC Fall5
2022 Compositions, decompositions, and conformability for total coloring on power of cycle graphs
Alesom Zorzi, Celina M. H. de Figueiredo, Raphael Machado, Leandro M. Zatesko, Uéverton S. Souza
Discret. Appl. Math.3
2020 Work-in-Progress: Compromising Security of Real-time Ethernet Devices by means of Selective Queue Saturation Attack
abstract
The industrial control systems (ICS) are using Real-Time Ethernet (RTE) protocols for many years. Today, Ethernet based control systems are widely used in industries. The Time Sensitive Networking (TSN) initiative will definitely push their further diffusion. With the introduction of Industry 4.0, production machines and their components have been connected to the Internet. Currently adopted RTE protocols do not require authentication, and hence may exchange data also with potentially malicious partners. In this paper, a selective Denial of Service (DoS) attack is presented. The proposed Selective Queue Saturation Attack (SQSA) is aimed to jam the message queue of the RTE communication stack in selected devices. The SQSA minimizes the chances of being detected by keeping its requirements (in term generated traffic) as low as possible. The SQSA has been applied to a real scenario based on PROFINET. The results of the use case demonstrate: the feasibility of the proposed attack; the reduced footprint compared to known DoS attacks (more than one thousand times less); and the selectivity of the attack, which can disrupt the realtime behavior of even a single target node inside the RTE network.
Paolo Ferrari 0001, Emiliano Sisinni, Abusayeed Saifullah, Raphael Machado, Alan Oliveira de Sá, M. Felser
WFCS4
2020 Bio-inspired Active System Identification: a Cyber-Physical Intelligence Attack in Networked Control Systems
Alan Oliveira de Sá, Luiz Fernando Rust da Costa Carmo, Raphael Machado
Mob. Networks Appl.3
2019 Full Characterization of a Class of Graphs Tailored for Software Watermarking
Lucila M. S. Bento, Davidson R. Boccardo, Raphael Machado, Vinícius G. P. de Sá, Jayme Luiz Szwarcfiter
Algorithmica3
2019 Dijkstra graphs
Lucila M. S. Bento, Davidson R. Boccardo, Raphael Machado, Flávio Keidi Miyazawa, Vinícius G. P. de Sá, Jayme Luiz Szwarcfiter
Discret. Appl. Math.3
2019 On the embedding of cone graphs in the line with distinct distances between neighbors
Rodrigo M. Zhou, Celina M. H. de Figueiredo, Raphael Machado, Vinícius G. P. de Sá
Discret. Appl. Math.3
2018 On the resilience of canonical reducible permutation graphs
Lucila M. S. Bento, Davidson R. Boccardo, Raphael Machado, Vinícius G. P. de Sá, Jayme Luiz Szwarcfiter
Discret. Appl. Math.3
2018 Using SPQR-trees to speed up recognition algorithms based on 2-cutsets
Hélio B. Macêdo Filho, Celina M. H. de Figueiredo, Raphael Machado
Discret. Appl. Math.4
2018 Using Physical Context-Based Authentication against External Attacks: Models and Protocols
abstract
Modern systems are increasingly dependent on the integration of physical processes and information technologies. This trend is remarkable in applications involving sensor networks, cyberphysical systems, and Internet of Things. Despite its complexity, such integration results in physical context information that can be used to improve security, especially authentication. In this paper, we show that entities sharing the same physical context can use it for establishing a secure communication channel and protecting each other against external attacks. We present such approach proposing a theoretical model for generating unique bitstreams. Two different protocols are suggested. Each one is evaluated using probabilistic analysis and simulation. In the end, we implement the authentication mechanism in a case study using networks radio signal as physical event generator. The results demonstrate the performance of each of the protocols and their suitability for applications in real world.
Wilson S. Melo Jr., Raphael Machado, Luiz Fernando Rust da Costa Carmo
Secur. Commun. Networks2
2017 Efficient Algorithms for Clique-Colouring and Biclique-Colouring Unichord-Free Graphs
Hélio B. Macêdo Filho, Raphael Machado, Celina M. H. de Figueiredo
Algorithmica2
2017 Genomic Distance with High Indel Costs
abstract
We determine complexity of computing the DCJ-indel distance, when DCJ and indel operations have distinct constant costs, by showing an exact formula that can be computed in linear time for any choice of (constant) costs for DCJ and indel operations. We additionally consider the problem of triangular inequality disruption and propose an algorithmically efficient correction on each member of the family of DCJ-indel.
Poly H. da Silva, Raphael Machado, Simone Dantas, Marília D. V. Braga
IEEE ACM Trans. Comput. Biol. Bioinform.2
2017 Covert Attacks in Cyber-Physical Control Systems
abstract
The advantages of using communication networks to interconnect controllers and physical plants motivate the increasing number of networked control systems in industrial and critical infrastructure facilities. However, this integration also exposes such control systems to new threats, typical of the cyber domain. In this context, studies have been conducted, aiming to explore vulnerabilities and propose security solutions for cyber-physical systems. In this paper, a covert attack for service degradation is proposed, which is planned based on the intelligence gathered by another attack, herein proposed, referred as system identification attack. The simulation results demonstrate that the joint operation of the two attacks is capable to affect, in a covert and accurate way, the physical behavior of a system.
Alan Oliveira de Sá, Luiz Fernando Rust da Costa Carmo, Raphael Machado
IEEE Trans. Ind. Informatics3
2016 Software control and intellectual property protection in cyber-physical systems
abstract
Software control is a critical issue in cyber-physical systems (CPS); if the expected behavior of the software embedded in a single device of a CPS cannot be enforced then the behavior of the whole CPS may be in jeopardy. Thus, CPS stakeholders like having some level of control over the embedded software. Third-party demands to control the software, however, conflict with the intellectual property protection demanded by software developers, since some level of detail about the software at hand would have to be disclosed. In the present paper, we discuss the issue of controlling the software embedded in CPS devices and address the problem of how to achieve an increased level of software control without compromising the protection of intellectual property. We propose a two-party fingerprinting scheme that allows for attribution of responsibility in the case of intellectual property leaks. Our fingerprinting scheme is such that neither party may obtain an advantage over the other by misbehaving, misrepresenting or by prematurely aborting the protocol, therefore providing a fair means to resolve disputes.
Raphael Machado, Davidson R. Boccardo, Vinícius G. P. de Sá, Jayme Luiz Szwarcfiter
EURASIP J. Inf. Secur.1
2016 Hierarchical complexity of 2-clique-colouring weakly chordal graphs and perfect graphs having cliques of size at least 3
Hélio B. Macêdo Filho, Raphael Machado, Celina M. H. de Figueiredo
Theor. Comput. Sci.2
2015 Fair Fingerprinting Protocol for Attesting Software Misuses
abstract
Digital watermarks embed information into a host artifact in such a way that the functionalities of the artifact remain unchanged. Allowing for the timely retrieval of authorship/ownership information, and ideally hard to be removed, watermarks discourage piracy and have thus been regarded as important tools to protect the intellectual property. A watermark aimed at uniquely identifying an artifact is referred to as a fingerprint. After presenting a formal definition of digital watermarks, we introduce an unbiased fingerprinting protocol -- based on oblivious transfer -- that lends no advantage to the prosecuting party in a dispute around intellectual property breach.
Raphael Machado, Davidson R. Boccardo, Vinícius G. P. de Sá, Jayme Luiz Szwarcfiter
ARES1
2015 Biclique-colouring verification complexity and biclique-colouring power graphs
Hélio B. Macêdo Filho, Simone Dantas, Raphael Machado, Celina M. H. de Figueiredo
Discret. Appl. Math.3
2015 On the recognition of unit disk graphs and the Distance Geometry Problem with Ranges
Guilherme Dias da Fonseca, Vinícius G. P. de Sá, Raphael Machado, Celina M. H. de Figueiredo
Discret. Appl. Math.3
2014 Hierarchical Complexity of 2-Clique-Colouring Weakly Chordal Graphs and Perfect Graphs Having Cliques of Size at Least 3
Hélio B. Macêdo Filho, Raphael Machado, Celina M. H. de Figueiredo
LATIN2
2014 Complexity of colouring problems restricted to unichord-free and { square, unichord }-free graphs
Raphael Machado, Celina M. H. de Figueiredo, Nicolas Trotignon
Discret. Appl. Math.1
2014 Efficient sub-5 approximations for minimum dominating sets in unit disk graphs
Guilherme Dias da Fonseca, Celina M. H. de Figueiredo, Vinícius G. P. de Sá, Raphael Machado
Theor. Comput. Sci.4
2013 Information security aspects of public software
abstract
Public Software can be defined as any software that is endorsed by a Public Agent and distributed for wide use by the society. The concept of Public Software is an outspread of the idea that "software" is an important asset for the welfare of society, and therefore providing citizens with proper software tools is a task of public interest, which in some cases should be performed by the government itself. When a Public Agent endorses a software and gives it the "seal" of Public Software, he is -- explicitly or implicitly -- declaring that such software complies with minimum technical requirements, and stimulates its wide use by the society In the present paper, we discuss the importance that such requirements encompasses Information Security and we propose a validation model that is strongly based on security evaluation. In a world where cyber-crime is a reality and cyber-war becomes more and more relevant, it is fundamental that the Public Agent verify the Information Security aspects of a software before declaring it a Public Software, for otherwise, this Public Agent can be stimulating that security flaws and vulnerabilities are spread in the society, possibly in critical applications. We additionally discuss the importance of a strong validation procedure to assure the appropriate behavior of software regarding its functionalities and Information Security aspects. We conclude describing the Brazilian experience with the "Brazilian Public Software Portal" Public Software repository of open-source software.
Henrique Soares, Raphael Machado, Bruno Salgado, Rafael Soares, Jarbas Lopes Cardoso Jr., Luis Felipe Costa
MEDES2
2013 Towards a Provably Resilient Scheme for Graph-Based Watermarking
Lucila M. S. Bento, Davidson R. Boccardo, Raphael Machado, Vinícius G. P. de Sá, Jayme Luiz Szwarcfiter
WG3
2012 Clique-Colouring and Biclique-Colouring Unichord-Free Graphs
Hélio B. Macêdo Filho, Raphael Machado, Celina M. H. de Figueiredo
LATIN2
2012 DCJ-indel Distance with Distinct Operation Costs
Poly H. da Silva, Marília D. V. Braga, Raphael Machado, Simone Dantas
WABI3
2012 Linear Time Approximation for Dominating Sets and Independent Dominating Sets in Unit Disk Graphs
Guilherme Dias da Fonseca, Celina M. H. de Figueiredo, Vinícius G. P. de Sá, Raphael Machado
WAOA4
2012 Restricted DCJ-indel model: sorting linear genomes with DCJ and indels
abstract
BACKGROUND: The double-cut-and-join (DCJ) is a model that is able to efficiently sort a genome into another, generalizing the typical mutations (inversions, fusions, fissions, translocations) to which genomes are subject, but allowing the existence of circular chromosomes at the intermediate steps. In the general model many circular chromosomes can coexist in some intermediate step. However, when the compared genomes are linear, it is more plausible to use the so-called restricted DCJ model, in which we proceed the reincorporation of a circular chromosome immediately after its creation. These two consecutive DCJ operations, which create and reincorporate a circular chromosome, mimic a transposition or a block-interchange. When the compared genomes have the same content, it is known that the genomic distance for the restricted DCJ model is the same as the distance for the general model. If the genomes have unequal contents, in addition to DCJ it is necessary to consider indels, which are insertions and deletions of DNA segments. Linear time algorithms were proposed to compute the distance and to find a sorting scenario in a general, unrestricted DCJ-indel model that considers DCJ and indels. RESULTS: In the present work we consider the restricted DCJ-indel model for sorting linear genomes with unequal contents. We allow DCJ operations and indels with the following constraint: if a circular chromosome is created by a DCJ, it has to be reincorporated in the next step (no other DCJ or indel can be applied between the creation and the reincorporation of a circular chromosome). We then develop a sorting algorithm and give a tight upper bound for the restricted DCJ-indel distance. CONCLUSIONS: We have given a tight upper bound for the restricted DCJ-indel distance. The question whether this bound can be reduced so that both the general and the restricted DCJ-indel distances are equal remains open.
Poly H. da Silva, Raphael Machado, Simone Dantas, Marília D. V. Braga
BMC Bioinform.2
2012 Program Matching through Code Analysis and Artificial Neural Networks
abstract
Program matching refers to the mapping between equivalent codes written in different languages — including high-level and low-level languages. This equivalence is useful for some software engineering scenarios such as determining whether rewritten code is correct, which version of a program is being used, and whether a malware is present in the program. In the present work, we propose a novel approach to solve the executable code traceability by using program code analysis and artificial neural networks. From the program code analysis we obtained execution behavior properties of the codes, and from the artificial neural networks we judge about their correspondence. Our evaluation using real code examples shows an acceptable correspondence rate between 62% and 100% with the very low rate of 4% false positives.
Tiago M. Nascimento, Davidson R. Boccardo, Charles B. Prado, Raphael Machado, Luiz Fernando Rust da Costa Carmo
Int. J. Softw. Eng. Knowl. Eng.4
2011 Genomic distance under gene substitutions
abstract
BACKGROUND: The distance between two genomes is often computed by comparing only the common markers between them. Some approaches are also able to deal with non-common markers, allowing the insertion or the deletion of such markers. In these models, a deletion and a subsequent insertion that occur at the same position of the genome count for two sorting steps. RESULTS: Here we propose a new model that sorts non-common markers with substitutions, which are more powerful operations that comprehend insertions and deletions. A deletion and an insertion that occur at the same position of the genome can be modeled as a substitution, counting for a single sorting step. CONCLUSIONS: Comparing genomes with unequal content, but without duplicated markers, we give a linear time algorithm to compute the genomic distance considering substitutions and double-cut-and-join (DCJ) operations. This model provides a parsimonious genomic distance to handle genomes free of duplicated markers, that is in practice a lower bound to the real genomic distances. The method could also be used to refine orthology assignments, since in some cases a substitution could actually correspond to an unannotated orthology.
Marília D. V. Braga, Raphael Machado, Leonardo Costa Ribeiro, Jens Stoye
BMC Bioinform.2
2011 On the weight of indels in genomic distances
abstract
BACKGROUND: Classical approaches to compute the genomic distance are usually limited to genomes with the same content, without duplicated markers. However, differences in the gene content are frequently observed and can reflect important evolutionary aspects. A few polynomial time algorithms that include genome rearrangements, insertions and deletions (or substitutions) were already proposed. These methods often allow a block of contiguous markers to be inserted, deleted or substituted at once but result in distance functions that do not respect the triangular inequality and hence do not constitute metrics. RESULTS: In the present study we discuss the disruption of the triangular inequality in some of the available methods and give a framework to establish an efficient correction for two models recently proposed, one that includes insertions, deletions and double cut and join (DCJ) operations, and one that includes substitutions and DCJ operations. CONCLUSIONS: We show that the proposed framework establishes the triangular inequality in both distances, by summing a surcharge on indel operations and on substitutions that depends only on the number of markers affected by these operations. This correction can be applied a posteriori, without interfering with the already available formulas to compute these distances. We claim that this correction leads to distances that are biologically more plausible.
Marília D. V. Braga, Raphael Machado, Leonardo Costa Ribeiro, Jens Stoye
BMC Bioinform.2
2011 Total chromatic number of unichord-free graphs
Raphael Machado, Celina M. H. de Figueiredo
Discret. Appl. Math.1
2011 A decomposition for total-coloring partial-grids and list-total-coloring outerplanar graphs
abstract
Abstract The total chromatic number χT(G) is the least number of colors sufficient to color the elements (vertices and edges) of a graph G in such a way that no incident or adjacent elements receive the same color. In the present work, we obtain two results on total‐coloring. First, we extend the set of partial‐grids classified with respect to the total‐chromatic number, by proving that every 8‐chordal partial‐grid of maximum degree 3 has total chromatic number 4. Second, we prove a result on list‐total‐coloring biconnected outerplanar graphs. If for each element x of a biconnected outerplanar graph G there exists a set Lx of colors such that |Luw| = max{deg(u) + 1, deg(w) + 1} for each edge uw and |Lv| = 7 − δdeg(v),3 − 2δdeg(v),2 (where δi,j = 1 if i = j and δi,j = 0 if i ≠ j) for each vertex v, then there is a total‐coloring π of graph G such that π(x) ∈ Lx for each element x of G. The technique used in these two results is a decomposition by a cutset of two adjacent vertices, whose properties are discussed in the article. © 2011 Wiley Periodicals, Inc. NETWORKS, 2011
Raphael Machado, Celina M. H. de Figueiredo
Networks1
2011 Complexity dichotomy on partial grid recognition
Vinícius G. P. de Sá, Guilherme Dias da Fonseca, Raphael Machado, Celina M. H. de Figueiredo
Theor. Comput. Sci.3
2010 Traceability of Executable Codes Using Neural Networks
Davidson R. Boccardo, Tiago M. Nascimento, Raphael Machado, Charles B. Prado, Luiz Fernando Rust da Costa Carmo
ISC3
2010 Decompositions for edge-coloring join graphs and cobipartite graphs
Raphael Machado, Celina M. H. de Figueiredo
Discret. Appl. Math.1
2010 Chromatic index of graphs with no cycle with a unique chord
Raphael Machado, Celina M. H. de Figueiredo, Kristina Vuskovic
Theor. Comput. Sci.1
2009 NP-Completeness of Determining the Total Chromatic Number of Graphs that do not Contain a Cycle with a Unique Chord
Raphael Machado, Celina M. H. de Figueiredo
CTW1
2008 A decomposition for total-coloring graphs of maximum degree 3
Raphael Machado, Celina M. H. de Figueiredo
CTW1