# Blockchain-Based Evidence Trustworthiness System in Certification
## 4 Secure Evidence Trustworthiness System  
Several proposals are already being made in the literature to guarantee the reliability of evidence [24]. In fact, the use of Blockchain has recently been considered for audit purposes [25; 26; 27]. However, there are solutions that have already been created with particular domains in mind, such as [28; 29; 30; 31] for the pharmaceutical, health, banking, and trading sectors, respectively, that do not consider the particularities of evidence considered inside a certification process. In addition, technical details are not often fully explained, and usability is usually not taken into account in spite of its growing importance [32] and the demand of auditors [33; 34]. Not all Blockchain technologies are suitable [35] for an evidence trustworthiness system. Public Blockchain networks, which are open to the public and that anyone can join without specific permission, are not suitable. In addition, all users who join the network can read, write, and participate in this network that is not controlled by anyone in particular. In contrast, permissioned Blockchains are based on invitation, and anyone who wants to access it must ask for permission from the governing body of the Blockchain. They allow different levels of access that determine which users can write, read, and audit the Blockchain. This control is required in an evidence trustworthiness system, in which the network should not be publicly accessible. Additionally, a permissioned Blockchain requires fewer nodes to be set up, making the network faster, more efficient, and more convenient in terms of time and energy consumption. Lastly, they can be free, which is highly beneficial for an evidence trustworthiness system in which numerous evidence records can be stored. Currently, the European Commission is actively supporting the development of Blockchain technology through various public initiatives under the European Blockchain Strategy, recognizing its significant potential to transform industries and improve the lives of citizens across Europe. One such initiative is the European Blockchain Services Infrastructure (EBSI), a network of nodes distributed throughout Europe that provides cross-border digital public services in compliance with European regulations, ensuring the highest standards of security and privacy [36]. The primary goal of EBSI is to leverage Blockchain technology to enhance interactions between citizens, governments, and businesses. It is the first EU-wide Blockchain infrastructure, driven by the public sector to support cross-border applications such as traceability, verifiable credentials, trusted data exchange (as could be the case in an evidence trustworthiness system), or IP management across multiple domains. Thus, EBSI is a suitable Blockchain ecosystem where one can deploy a European evidence trustworthiness system. EBSI leverages Hyperledger Besu [37], which is an Ethereum client suitable for not only public but also private permissioned Blockchain network use cases, such as the trustworthiness system. As EBSI is considered a suitable Blockchain ecosystem in which to deploy a European trustworthiness system, and it uses Hyperledger Besu, the suggested Blockchain-based evidence trustworthiness system for certification should be based on Ethereum-like technologies. In this sense, the Blockchain-based audit trail system presented by the authors in [38] has been considered as the basis for the evidence trustworthiness system. It is a multi-domain general purpose audit trail solution in which usability is prioritized, technical details are described, and several features that are really useful for an evidence trustworthiness system in certification are covered. * Inalterability: Ensuring the integrity of evidence is crucial, and Blockchain guarantees this by design. * Long-term maintenance: Evidence must remain accessible even years after certification expiration, which Blockchain ensures as long as the network is operational.