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Publications

Publications by HASLab

2024

A Distributed Computing Solution for Privacy-Preserving Genome-Wide Association Studies

Authors
Brito, C; Ferreira, P; Paulo, J;

Publication

Abstract
AbstractBreakthroughs in sequencing technologies led to an exponential growth of genomic data, providing unprecedented biological in-sights and new therapeutic applications. However, analyzing such large amounts of sensitive data raises key concerns regarding data privacy, specifically when the information is outsourced to third-party infrastructures for data storage and processing (e.g., cloud computing). Current solutions for data privacy protection resort to centralized designs or cryptographic primitives that impose considerable computational overheads, limiting their applicability to large-scale genomic analysis.We introduce Gyosa, a secure and privacy-preserving distributed genomic analysis solution. Unlike in previous work, Gyosafollows a distributed processing design that enables handling larger amounts of genomic data in a scalable and efficient fashion. Further, by leveraging trusted execution environments (TEEs), namely Intel SGX, Gyosaallows users to confidentially delegate their GWAS analysis to untrusted third-party infrastructures. To overcome the memory limitations of SGX, we implement a computation partitioning scheme within Gyosa. This scheme reduces the number of operations done inside the TEEs while safeguarding the users’ genomic data privacy. By integrating this security scheme inGlow, Gyosaprovides a secure and distributed environment that facilitates diverse GWAS studies. The experimental evaluation validates the applicability and scalability of Gyosa, reinforcing its ability to provide enhanced security guarantees. Further, the results show that, by distributing GWASes computations, one can achieve a practical and usable privacy-preserving solution.

2024

Mastering Artifact Correction in Neuroimaging Analysis: A Retrospective Approach

Authors
Oliveira, A; Cepa, B; Brito, C; Sousa, A;

Publication

Abstract
The correction of artifacts in Magnetic Resonance Imaging (MRI) is increasingly relevant as voluntary and involuntary artifacts can hinder data acquisition. Reverting from corrupted to artifact-free images is a complex task. Deep Learning (DL) models have been employed to preserve data characteristics and to identify and correct those artifacts. We propose MOANA, a novel DL-based solution to correct artifacts in multi-contrast brain MRI scans. MOANA offers two models: the simulation and the correction models. The simulation model introduces perturbations similar to those occurring in an exam while preserving the original image as ground truth; this is required as publicly available datasets rarely have motion-corrupted images. It allows the addition of three types of artifacts with different degrees of severity. The DL-based correction model adds a fourth contrast to state-of-the-art solutions while improving the overall performance of the models. MOANA achieved the highest results in the FLAIR contrast, with a Structural Similarity Index Measure (SSIM) of 0.9803 and a Normalized Mutual Information (NMI) of 0.8030. With this, the MOANA model can correct large volumes of images in less time and adapt to different levels of artifact severity, allowing for better diagnosis.

2024

Mastering Artifact Correction in Neuroimaging Analysis: A Retrospective Approach

Authors
Oliveira, A; Cepa, B; Brito, C; Sousa, A;

Publication

Abstract
The correction of artifacts in Magnetic Resonance Imaging (MRI) is increasingly relevant as voluntary and involuntary artifacts can hinder data acquisition. Reverting from corrupted to artifact-free images is a complex task. Deep Learning (DL) models have been employed to preserve data characteristics and to identify and correct those artifacts. We propose MOANA, a novel DL-based solution to correct artifacts in multi-contrast brain MRI scans. MOANA offers two models: the simulation and the correction models. The simulation model introduces perturbations similar to those occurring in an exam while preserving the original image as ground truth; this is required as publicly available datasets rarely have motion-corrupted images. It allows the addition of three types of artifacts with different degrees of severity. The DL-based correction model adds a fourth contrast to state-of-the-art solutions while improving the overall performance of the models. MOANA achieved the highest results in the FLAIR contrast, with a Structural Similarity Index Measure (SSIM) of 0.9803 and a Normalized Mutual Information (NMI) of 0.8030. With this, the MOANA model can correct large volumes of images in less time and adapt to different levels of artifact severity, allowing for better diagnosis.

2024

An adequacy theorem between mixed powerdomains and probabilistic concurrency

Authors
Neves, R;

Publication
CoRR

Abstract

2024

Flow Correlation Attacks on Tor Onion Service Sessions with Sliding Subset Sum

Authors
Lopes, D; Dong, JD; Medeiros, P; Castro, D; Barradas, D; Portela, B; Vinagre, J; Ferreira, B; Christin, N; Santos, N;

Publication
31st Annual Network and Distributed System Security Symposium, NDSS 2024, San Diego, California, USA, February 26 - March 1, 2024

Abstract

2024

Extending C2 Traffic Detection Methodologies: From TLS 1.2 to TLS 1.3-enabled Malware

Authors
Barradas, D; Novo, C; Portela, B; Romeiro, S; Santos, N;

Publication
PROCEEDINGS OF 27TH INTERNATIONAL SYMPOSIUM ON RESEARCH IN ATTACKS, INTRUSIONS AND DEFENSES, RAID 2024

Abstract
As the Internet evolves from TLS 1.2 to TLS 1.3, it offers enhanced security against network eavesdropping for online communications. However, this advancement also enables malicious command and control (C2) traffic to more effectively evade malware detectors and intrusion detection systems. Among other capabilities, TLS 1.3 introduces encryption for most handshake messages and conceals the actual TLS record content type, complicating the task for state-of-the-art C2 traffic classifiers that were initially developed for TLS 1.2 traffic. Given the pressing need to accurately detect malicious C2 communications, this paper examines to what extent existing C2 classifiers for TLS 1.2 are less effective when applied to TLS 1.3 traffic, posing a central research question: is it possible to adapt TLS 1.2 detection methodologies for C2 traffic to work with TLS 1.3 flows? We answer this question affirmatively by introducing new methods for inferring certificate size and filtering handshake/protocolrelated records in TLS 1.3 flows. These techniques enable the extraction of key features for enhancing traffic detection and can be utilized to pre-process data flows before applying C2 classifiers. We demonstrate that this approach facilitates the use of existing TLS 1.2 C2 classifiers with high efficacy, allowing for the passive classification of encrypted network traffic. In our tests, we inferred certificate sizes with an average error of 1.0%, and achieved detection rates of 100% when classifying traffic based on certificate size, and over 93% when classifying TLS 1.3 traffic behavior after training solely on TLS 1.2 traffic. To our knowledge, these are the first findings to showcase specialized TLS 1.3 C2 traffic classification.

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