## 4 Implementation of the System
### Usability and User Experience  
A well-designed User Experience (UX) is crucial for the widespread adoption of DLT-based applications. The development of such applications is usually challenging because, beyond adhering to established best practices and modern standards (such as user-centric design, intuitive navigation, consistency or responsiveness), it must also ensure that interactions with DLTs are as seamless and transparent as possible to encourage user adoption [94]. Since the solution proposed in this article was conceived as a technical demonstration for practitioners, developers and researchers, no UI frameworks were used. In addition, the number of interface elements and available options was kept as small as possible to create an easy-to-use verification system. In order to evaluate the UX of the developed interface, an exploratory assessment was carried out to obtain feedback from potential users of the platform. The interviewees represented a range of backgrounds, encompassing the three different roles: students (aged 18-25), professors (aged 28-35), administrators (aged 35-40) and human resource managers (aged 35-40). The list of available tasks for the students, professors and the human resources manager to evaluate the application is shown in Tables 2, 3 and 4, respectively. The group sample size was small, but their feedback was really valuable for obtaining an initial exploratory understanding of the UX and for identifying potential issues at an early stage. The participants raised several interesting points. First, the use of a decentralized application requires the use of a wallet and even though wallet providers have detailed instructions in their websites on how to set them up, it was a barrier for the interviewed users, who wondered why they had to leave the application in order to install it (Tasks 1-4 in Tables 2 and 3). Second, as it was mentioned in Section 3.2.1, users are required to sign a message in order to log-in in the application (Task 5 in Tables 2 and 3). Words like \"Sign text\", \"Verify signature\", \"Public key\" (Figure 7) were not familiar for both students and professors. Moreover, it was suggested that a step-by-step guidance would be better than having all the input fields in the same place. This modification is straightforward and can be easily achieved by integrating a progress bar with tool tips, descriptive texts and help icons to explain the required inputs and their purpose. Thus, after completing the account validation process, students were able to see their AR (Figure 8). In this panel, there is only one button that allows for downloading the AR (Figure 11). The simplicity of inspecting and sharing the AR was highly appreciated, but was complemented with the suggestion to support additional user-friendly and widely recognized file formats, such as PDF (Task 8 in Table 2). Regarding the administrators, their panel showed a set of ARs that changed since the last update, and a button to confirm such changes in the blockchain. Although they knew that their function was to confirm the changes that took place in the database of the university, they wanted to understand what implied the transaction to the blockchain (Task 6 in Table 3). Some testers acknowledged that managing up to a high number of ARs could become difficult with the current implementation. They appreciated the system technical scalability and identified an opportunity to improve scalability from a UX \begin{table}
\begin{tabular}{c l l} \hline \hline
**No.** & **Task** & **Explanation** \\ \hline
1 & Get a set of ARs & Inspect a set of ARs, some of which have been fraudulently modified. \\ \hline
2 & Verify ARs & Introduce the AR in the application and react to the result. \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Evaluation tasks for the human resources manager.