REPUTABLE: A Provenance-aware Decentralized Reputation System for Blockchain-based Ecosystems

Blockchain has emerged as a disruptive paradigm which enables immutable transactions without the presence of a trusted third-party. Consequently, it has been adopted to achieve trustworthy applications across diverse domains such as healthcare, manufacturing, and finance. With such advancements, the need for blockchain-based applications to interact with external services and applications is increasingly evident which requires investigating challenges with respect to trustworthy interactions and efficient management of relevant data. 

Reputation systems typically utilise user feedback to evaluate the reputation of a service, affecting its trustworthiness as perceived by the prospective users. Contemporary reputation systems involve a centralized authority to administer, aggregate and analyse user inputs to model the reputation of a service. Although reputation systems can help achieve trustworthy interactions with external services within a blockchain ecosystem, centralized approaches have inherent limitations. Furthermore, as reputation systems rely on user inputs, trustworthy management (collection, tracking, storage & processing) of such data feeds is critical to overall effectiveness of a reputation system. In this respect, although blockchain technology provides basic characteristics such as immutable transactions, there is need to strengthen these capabilities to achieve trustworthy management of external (off-chain) data feeds.

The project involves developing a decentralized, verifiable reputation system which investigates the challenge of achieving trustworthy reputation modelling of external services within a blockchain ecosystem (ONTOCHAIN). Specifically, the project will explore development of a reputation system for external (off-chain) services whilst preserving security, privacy, accountability and unlinkability of participants and their responses. Further, the project will involve development of bespoke digital solutions (using smart contracts and oracles) to enhance core capabilities of blockchain with respect to provenance of external data feeds achieving trustworthiness of the reputation modelling system. The project envisages engaging with selected ONTOCHAIN applications to evaluate proposed solutions within real-world scenarios.



Motivation for the project:

REPUTABLE project is aimed at developing a provenance-aware decentralized reputation system to enhance trustworthiness of external services as perceived by the end-users. 

Generic use case description

A generic use-case can be reputation modelling and management of third-party web services which require adherence to service level agreements/ quality of service objectives. The data feeds from such external services are captured and recorded within a consensus blockchain and processed to calculate reputation scores.

Essential functionalities:

- Development of a prototype decentralized reputation system which is able to gather, process and store user feedback.
- Proof of concept implementation of the provenance layer through technologies such as smart contracts.
- Facilities for reputation data management (storage and analysis) through on-chain/off-chain methods such as clouds.

How these functionalities can be integrated within the software ecosystem:

The proposed functionalities can be integrated through interoperable development of components such as the provenance layer and decentralized reputation system.

Gap being addressed:

The gap being addressed is the development of a decentralized reputation system for external services which is underpinned by trustworthy data feeds achieve through blockchain-based provenance mechanism.

Expected benefits achieved with the novel technology building blocks:

The project will enable provenance-aware reputation modelling of services delivered through the ONTOCHAIN platform. This will achieve trustworthy service provisioning for end users through tamper-proof reputation modelling. 

Potential demonstration scenario:

A demonstration scenario can be reputation modelling of external services where the reputation data is stored in the form of transactions within the consensus blockchain through the execution of smart contracts while its associated metadata for reputation will be stored and managed at off-chain storage.








Collaborative R&D is the ethos of the ONTOCHAIN initiative and it has also been our primary motive to join the programme. Through this programme, we have been able to advance our ideas in a structured way to a proof of concept implementation. The governance structure adopted by the programme has been really useful in having detailed technical discussions on a weekly basis which has also ensured timely delivery of our objectives and KPIs.

- Dr Junaid Arshad



Dr. J Arshad

Dr. Junaid Arshad

Cybersecurity researcher and an Associate Professor at the Birmingham City University, UK.


Dr. M A Azad

Dr. Muhammad Ajmal Azad

Senior Lecturer in Cyber Security at the University of Derby, UK



Birmingham City University

Birmingham City University is a large and diverse place to study with around 24,000 students from 80 countries.