arXiv subjects

Khuong Nguyen-An

Publications and source records attributed to Khuong Nguyen-An.

5 recordsLinked to original sources

arXiv2026

Design and Evaluation of a Controlled Post-Alert Incident Orchestration and Response Subsystem Using a Rule Engine and a Local Large Language Model

This paper presents a controlled post-alert incident orchestration and response subsystem for educational information systems. The architecture separates deterministic classification, contextual analysis, human approval, and technical execution. A Rule Engine determines severity and selects the playbook, while Static RAG and a local large language model provide advisory content under Validator, Guardrail, Output Sanitizer, and Safe Fallback controls. Experiments begin after simulated alerts are stored in Elasticsearch. The Rule Engine matched the predefined routing matrix in all 30 boundary cases. The Durable Queue completed 100 events without duplicate tasks, new failed tasks, or unintended firewall rules. An eight-alert contention experiment preserved the configured limit of one active model request, and 30 sequential measurements showed an overall mean post-alert processing time of approximately 33 seconds. The results demonstrate functional correctness, traceability, controlled recovery, and bounded model integration within the evaluated laboratory scope.

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arXiv2026

Passive Hybrid Network-Based Intrusion Detection System (Hybrid-NIDS) Combining Suricata and Random Forest

This paper evaluates a passive Hybrid Network-based Intrusion Detection System (Hybrid-NIDS) prototype that combines Suricata with Random Forest flow classification and centralized ELK-based alert handling. The study explicitly separates benchmark evaluation from PCAP/live operational validation and controls exact feature-duplicate leakage using feature hashing and group-aware splitting. From 2,540,047 UNSW-NB15 records, 453 conflicting-label hash groups containing 1,879 rows were removed; the resulting Development and Hold-out sets have zero exact feature-hash overlap. RF-41 achieved F1 = 0.971360 and ROC-AUC = 0.999671, while the NFStream-compatible RF-21 achieved F1 = 0.970148 on the same prepared hold-out boundary. However, operational validation revealed substantial benchmark-to-deployment domain shift: on a labeled laboratory PCAP, RF-21 and the strictly correlated branch achieved recall of only 0.0095, and RF-21 produced no alerts in five additional 60-second attack sessions. An unlabeled normal-traffic test produced 439 alerts from 2,375 flows; this value is reported only as an alert ratio and is not interpreted as a false-positive rate. These results show that strong performance on a public benchmark does not directly translate into operational effectiveness. Accordingly, the current Hybrid-NIDS should be interpreted as a passive prototype and evaluation framework, and the reported experiments do not demonstrate that Suricata-Random Forest correlation provides better operational detection than Suricata alone.

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arXiv2025

Publicly Verifiable Secret Sharing: Generic Constructions and Lattice-Based Instantiations in the Standard Model

Publicly verifiable secret sharing (PVSS) allows a dealer to share a secret among a set of shareholders so that the secret can be reconstructed later from any set of qualified participants. In addition, any public verifier should be able to check the correctness of the sharing and reconstruction process. PVSS has been demonstrated to yield various applications, such as e-voting, distributed key generation, decentralized random number generation protocols, and multi-party computation. Although many concrete PVSS protocols have been proposed, their security is either proven in the random oracle model or relies on quantum-vulnerable assumptions such as factoring or discrete logarithm. In this work, we put forward a generic construction for PVSS that can be instantiated in the standard model under the Learning With Errors (LWE) assumption. Our instantiation provides the first post-quantum PVSS in the standard model, with a reasonable level of asymptotic efficiency.

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arXiv2025

Post-Quantum Secure Decentralized Random Number Generation Protocol with Two Rounds of Communication in the Standard Model

Randomness plays a vital role in numerous applications, including simulation, cryptography, distributed systems, and gaming. Consequently, extensive research has been conducted to generate randomness. One such method is to design a decentralized random number generator (DRNG), a protocol that enables multiple participants to collaboratively generate random outputs that must be publicly verifiable. However, existing DRNGs are either not secure against quantum computers or depend on the random oracle model (ROM) to achieve security. In this paper, we design a DRNG based on lattice-based publicly verifiable secret sharing (PVSS) that is post-quantum secure and proven secure in the standard model. Additionally, our DRNG requires only two rounds of communication to generate a single (pseudo)random value and can tolerate up to any t < n/2 dishonest participants. To our knowledge, the proposed DRNG construction is the first to achieve all these properties.

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arXiv2024

An Integral Equation Approach for the Valuation of Finite-maturity margin-call Stock Loans

This paper examines the pricing issue of margin-call stock loans with finite maturities under the Black-Scholes-Merton framework. In particular, using a Fourier Sine transform method, we reduce the partial differential equation governing the price of a margin-call stock loan into an ordinary differential equation, the solution of which can be easily found (in the Fourier Sine space) and analytically inverted into the original space. As a result, we obtain an integral representation of the value of the stock loan in terms of the unknown optimal exit prices, which are, in turn, governed by a Volterra integral equation. We thus can break the pricing problem of margin-call stock loans into two steps: 1) finding the optimal exit prices by solving numerically the governing Volterra integral equation and 2) calculating the values of margin-call stock loans based on the obtained optimal exit prices. By validating and comparing with other available numerical methods, we show that our proposed numerical scheme offers a reliable and efficient way to calculate the service fee of a margin-call stock loan contract, track the contract value over time, and compute the level of stock price above which it is optimal to exit the contract. The effects of the margin-call feature on the loan contract are also examined and quantified.

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