By Bernd Ludwig Wenning & Pasindu Manisha Kuruppuarachchi, MTU*
What is trust?
Generally speaking, trust is a confidence or belief that someone or something acts in an expected, benevolent way. If that someone or something does so, they will build trust over time. In contrast, if they behave erratically or malevolent, trust in them will erode.
For an IoT system, this means the system works as expected within its parameters, performing its duties as intended and not showing any unexpected or unwanted behaviour. The Industrial Internet Consortium (IIC) has defined five categories that contribute to trust in a system: safety, security, privacy, reliability, and resilience [1]. We further extend this by two more categories: uncertainty/dependability and goal analysis.
Hence, we consider trust and trustworthiness to be evaluated in these seven Trust Evaluation Categories (TECs):
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Safety: Ensures that the system operates without causing harm to users, the environment, or other systems under both normal and abnormal conditions.
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Security: Protects the system from unauthorized access, malicious attacks, and data breaches, ensuring integrity, confidentiality, and availability.
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Privacy: Protects personal and sensitive information, ensuring compliance with data protection regulations and user consent.
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Reliability: Measures the system’s ability to perform its intended functions consistently and accurately over time.
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Resilience: Evaluates the system’s capacity to recover and maintain functionality during and after disruptions or failures.
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Uncertainty/Dependability: Assesses the system’s behaviour under uncertain conditions or with inputs of uncertain nature and its ability to deliver expected outcomes despite variability.
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Goal Analysis: Examines the alignment of the system’s objectives and operations with user needs, ensuring that trust-related goals are met effectively.
Trust in the context of TELEMETRY
TELEMETRY develops tools and methodologies for cyber security testing and monitoring of IoT ecosystems. The various tools in this project therefore produce outputs that can indicate aspects of the system’s trustworthiness, e.g., if anomalies are detected, these will have an impact on the system’s posture with regard to the TECs mentioned above.
To this end, a Trust Analyser is developed in TELEMETRY that assesses the overall trustworthiness of an IoT system based on the reports (“indicators”) from various tools and their mapping to TECs. Rather than the short-term identification of anomalies and incidents, this trustworthiness assessment is a long-term metric that builds over time. Long periods without incidents or anomalies will increase the trustworthiness, while any incident may lead to a more or less prominent decrease of trustworthiness, depending on the severity of the incident.
One key challenge is the aggregation of indicators and TECs into an overall trust metric. As not all tools report at the exact same time, the Trust Analyser has to use time windows, so called evaluation cycles, in which the reports are collected and then aggregated for scoring the individual TECs and the overall trustworthiness. The length of these evaluation cycles is a trade-off between how responsive the Trust Analyser is and how complete the set of reports is that is used for scoring. Weighting the individual TECs is another challenge in aggregation. The weights can be used to prioritise certain TECs over others, based on their importance to the use case.
A basic approach to aggregation is to use a weighted average of the individual TECs. This is the initial version of trust aggregation used in TELEMETRY. However, the research doesn’t stop here: Machine Learning methods are being explored that aim to achieve highly accurate trust assessment, ideally while maintaining explainability of what led to the assessment, so that a system operator can understand where the issue lies when the system’s trust is declining. Early results on this have been published in a conference paper [2].
Smart Manufacturing Use Case
One of the use cases in TELEMETRY is the smart manufacturing use case, UC2. In this use case, TELEMETRY tools are applied to a smart manufacturing system with a robot and other IoT components. The use case includes tools to monitor device behaviour, such as detecting whether a robot operates within its expected parameters, and other tools that monitor the network for anomalies. Indicators from these tools can be ingested by the Trust Analyser and mapped to the TECs as mentioned above. The Trust Analyser then assesses each one of the TECs and subsequently the overall trust score for the environment. The score will inform the smart manufacturing operator whether their environment is trustworthy with regard to the TECs, or whether there is any issue of concern. A dashboard provides them with a view on the overall score, on individual TECs and the indicators that contributed to the TECs.
Conclusion
Trust evaluation is an element of the overall cyber security evaluation that TELEMETRY tools aim to provide. It is a long-term evaluation of a system which indicates how trustworthy that system is in terms of seven Trust Evaluation Categories. Research is ongoing on aspects of how cyber security indicators are mapped to these categories, and how the categories are aggregated to a meaningful overall trust score that can inform an operator about their system’s overall long-term trustworthiness.
References
[1] Industrial Internet Consortium. The Industrial Internet of Things: Managing and Assessing Trustworthiness for IIoT in Practice. pages 1–40, 2019.
[2] P. M. Kuruppuarachchi, A. McGibney, S. Rea and B.-L. Wenning, “Machine Learning Based Trust Aggregation for IoT Systems,” 2025 IEEE International Conference on Smart Computing (SMARTCOMP), Cork, Ireland, 2025, pp. 282-287, doi: 10.1109/SMARTCOMP65954.2025.00087.
*Bernd-Ludwig Wenning is a Research Fellow at Munster Technological University (MTU) in Cork, Ireland. He holds Dipl.-Ing. and Dr.-Ing. degrees in electrical engineering and information technology from the University of Bremen, Germany.
In 2012, he joined the Nimbus Centre at MTU. Since then, he has worked on several national and EU funded projects. His research interests include mobile and wireless networks and protocols, IoT and cyber physical systems. Throughout his research career, he has authored or co-authored more than 50 publications.
Pasindu Manisha Kuruppuarachchi received his Bachelor’s degree in Computer Systems and Networking from the Sri Lanka Institute of Information Technology. He later earned his Master’s degree in Engineering and Technology from Thammasat University, Thailand. He completed his Doctoral degree at Munster Technological University, Cork, Ireland, where his research focused on developing collaborative digital twin ecosystems under the Nimbus Research Centre. His research interests include digital twins, blockchain technologies, agentic AI development, and interpretable AI solutions.
