Real-world blockchain applications under the lens of the oracle problem. A systematic literature review

As they have become leading topics of meetings, events and conferences, real-world blockchain applications have turned niche literature into a vast and complex plethora of books, articles and papers. Unlike digital payments, however, real-world applications are dependent on oracles, whose roles and implications are often neglected in the literature. The presence of oracles negatively affects decentralization and trustless consensus, generating faulty thinking or overly positive expectations. This paper aims to enlighten the state of the art of real-world blockchain applications through a systematic literature review, exploiting the oracle problem as a lens of analysis. The results support the view that almost 90% of the inspected literature is biased or incomplete.