# Trusted Academic Transcripts on the Blockchain: A Systematic Literature Review
## 5 Contribution Overview
### Managing Trust and the Oracle Problem  
The second research question focuses on contributions related to oracles and the oracle problem. By merely searching \"oracle\" and \"oracle problem\" strings in the text of papers collected, it seems that no research directly addressed the issue. Considering the unlikelihood of a complete neglection of the topic, we searched for contributions tackling the oracle problem by building on recent research [93]. Since the oracle problem is related to the trustworthiness of data provided to the blockchain, we searched for sentences involving the concept of trust and trustworthiness of information using computer-based text searches and, where not possible, by reading a paper in its entirety. The sample was then classified according to the recursion and pertinence. Selection criteria were the following:  
**In-depth:** Dedicated paragraphs or the entire paper to data trustworthiness  
**Good:** Multiple discussion on the data trustworthiness  
**Moderate:** one or few sentences on the trust concept  
**Little:** one or few uses of the trust concept and words  
**No:** No discussion or reference to trust throughout the paper  
As Figure 7 shows, nearly 70% of the sample dedicated little (23%) or no (47%) discussion over the trustworthiness of data on the blockchain and exclusively focused on technical aspects. After full-text reading, the contribution that considered the oracle problem to a sufficient level is the paper by [PERSON] and [PERSON] [18]. Throughout the article, they specified multiple times that no guarantees are given on the data uploaded on the blockchain, also saying that \"_A university could still award a bogus certificate, or a student could chet in an exam_\". Their model based on Kudos reproduces a trust mechanism such as the one used by Uber or Airbnb. Kudos should represent the reputation that students obtain by passing exams. Although the idea has fascinating roots, the paper does not give an exhaustive explanation of how this should technically function. Building on this paper, [PERSON] et al. [74] propose that the choice of awarding a skill to a student should not be completely in the hand of the instructor. Their model requires the student to solve a puzzle (test) based on the acquiring skill, and if successfully completed, Kudos are awarded; otherwise, they are lost. [PERSON] et al. [83] offered a similar approach, which proposes a bi-directional trust mechanism. Although students earn badges by passing exams, they can also evaluate the performance of the professor and the institution by deciding to issue or not a badge back to the professor. Exciting but incomplete, the presented project did not clearly specify the platform's architecture along with the consensus mechanism. On the other hand, many authors  
Figure 7: Consideration over the trustworthiness of data. agree [46; 70] that an open platform could be more adaptable for academic applications as data should be publicly auditable. Furthermore, certificate issuers should be known and identifiable. Despite being more privacy-friendly, a completely anonymous space would be more exposed to collusion [94]. [PERSON] et al. [71] also explain that an academic blockchain application's \"entire communication channel\" needs to be trusted since _\"It is always possible to upload spurious records on the blockchain\"_. In [PERSON] et al. [88], the concept of a trusted environment is managed differently. Inspired by EduCTX, their approach based on Ark requires that the blockchain applications start from a trusted group of few academic entities, from which senior members can invite more peers. Information on the blockchain is then shared and recognized as valuable by all the institutions (nodes) that belong to the same trusted group. Finally, exciting research by [PERSON] et al. [16] proposes an incentivization mechanism based on a Vickrey-Clarke-Groves (VCG) Nash equilibrium to ensure a trustworthy platform.