arXiv subjects

Leo Freitas

Publications and source records attributed to Leo Freitas.

7 recordsLinked to original sources

arXiv2025

Translating a VDM Model of a Medical Device into Kapture

As the complexity of safety-critical medical devices increases, so does the need for clear, verifiable, software requirements. This paper explores the use of Kapture, a formal modelling tool developed by D-RisQ, to translate an existing formal VDM model of a medical implant for treating focal epilepsy called CANDO. The work was undertaken without prior experience in formal methods. The paper assess Kapture's usability, the challenges of formal modelling, and the effectiveness of the translated model. The result is a model in Kapture which covers over 90% of the original VDM model, and produces matching traces of results. While several issues were encountered during design and implementation, mainly due to the initial learning curve, this paper demonstrates that complex systems can be effectively modelled in Kapture by inexperienced users and highlights some difficulties in translating VDM specifications to Kapture.

cs.SE↗

arXiv2024

Proceedings of the 22nd International Overture Workshop

This volume contains the papers presented at the 22nd International Overture Workshop, held on the 10th of September 2024. This event was the latest in a series of workshops around the Vienna Development Method (VDM), the open-source project Overture, and related tools and formalisms. VDM is one of the longest established formal methods for systems development. A lively community of researchers and practitioners has grown up in academia and industry has grown around the modelling languages (VDM-SL, VDM++, VDM-RT, CML) and tools (VDMTools, Overture, Crescendo, Symphony, the INTO-CPS chain, and ViennaTalk). Together, these provide a platform for work on modelling and analysis technology that includes static and dynamic analysis, test generation, execution support, and model checking. This workshop provided updates on the emerging technology of VDM/Overture, including collaboration infrastructure, collaborative modelling and co-simulation for Cyber-Physical Systems.

cs.SE↗

arXiv2023

International System of Quantities library in VDM

The International Systems of Quantities (ISQ) standard was published in 1960 to tame the wide diversity of measurement systems being developed across the world, such as the centimetre-gram-second versus the meter-kilogram-second for example. Such a standard is highly motivated by the potential of ``trivial'' (rather error-prone) mistakes in converting between incompatible units. There have been such accidents in space missions, medical devices, etc. Thus, rendering modelling or simulation experiments unusable or unsafe. We address this problem by providing a \textbf{SAFE}-ISQ VDM-library that is: Simple, Accurate, Fast, and Effective. It extends an ecosystem of other VDM mathematical toolkit extensions, which include a translation and proof environment for VDM in Isabelle at https://github.com/leouk/VDM_Toolkit.

cs.SE↗

arXiv2023

Topologically sorting VDM-SL definitions for Isabelle/HOL translation

There is an ecosystem of VDM libraries and extensions that includes a translation and proof environment for VDM in Isabelle. Translation works for a large subset of VDM-SL and further constructs are being added on demand. A key impediment for novice users is that Isabelle/HOL requires all definitions to be declared before they are used, where (mutually) recursive definitions must be defined in tandem. In this paper, we describe a solution to this problem, which will enable wider access to the translator plugin for novice users as well as real models.

cs.PL↗

arXiv2023

VDM recursive functions in Isabelle/HOL

For recursive functions general principles of induction needs to be applied. Instead of verifying them directly using the Vienna Development Method Specification Language (VDM-SL), we suggest a translation to Isabelle/HOL. In this paper, the challenges of such a translation for recursive functions are presented. This is an extension of an existing translation and a VDM mathematical toolbox in Isabelle/HOL enabling support for recursive functions.

cs.FL↗

arXiv2023

Specification-based CSV Support in VDM

CSV is a widely used format for data representing systems control, information exchange and processing, logging, etc. Nevertheless, the format is riddled with tricky corner cases and inconsistencies, which can make input data unreliable, thus, rendering modelling or simulation experiments unusable or unsafe. We address this problem by providing a SAFE-CSV VDM-library that is: Simple, Accurate, Fast, and Effective. It extends an ecosystem of other VDM mathematical toolkit extensions, which also includes a translation and proof environment for VDM in Isabelle

cs.SE↗

arXiv2020

Security Analysis of the Open Banking Account and Transaction API Protocol

The Second Payment Services Directive (PSD2) of the European Union aims to create a consumer-friendly financial market by mandating secure and standardised data sharing between banking operators and third parties. Consequently, EU countries and the United Kingdom have adopted Open Banking, a standardised data-sharing API. This paper presents a formal modelling and security analysis of the UK Open Banking Standard's APIs, with a specific focus on the Account and Transaction API protocol. Our methodology employs the extended Alice and Bob notation (AnBx) to create a formal model of the protocol, which is then verified using the OFMC symbolic model checker and the Proverif cryptographic protocol verifier. We extend previous work by enabling verification for unlimited sessions with a strongly typed model. Additionally, we integrate our formal analysis with practical security testing of some necessary conditions to demonstrate verified security-goals in the NatWest Open Banking sandbox, evaluating mechanisms such as authorisation and authentication procedures.

cs.CR↗