# Overview of Blockchain Oracle Research
## 5 Converging Studies, Research Themes, and Research Directions
### Oracle Applied  
Oracle-applied research is focused on various sectors. As expected, because of the resonance and hype that cryptocurrencies attract, finance applications constitute the widest sample. Although multiple institutions have investigated the subject, they show similarities in their focus. Studies from Concordia University, the University of Houston, and the University of Singapore focused on the very role of DeFi oracles: how they work, how they are designed, and how they interact with the underlying blockchain. Existing oracle types are also compared (in terms of efficiency), analyzing how data are retrieved, aggregated, and pushed into the blockchain [1,48]. [PERSON] and [PERSON] [82] also provided an overview of the percentage of DeFi oracle calls over total oracle calls. They discovered that almost 75% of ChainLink oracle calls are from Synthetics, a derivative-based DeFi project. Other studies from the University of Verona and Delhi Technological University focus on known threats to DeFi oracles. Although some, such as technical malfunctions or Sybil attacks, are efficiently spotted and addressed, others, such as frontrunning or flash loans, are still difficult to prevent and sometimes even to spot [46,83]. Three studies from Concordia University, Delhi University, and Delft University of Technology focused on the role of the oracle as a means to manipulate the market, showing the possible risks connected with its use and misuse [48,83,84]. Whereas the first two have a more theoretical slant, the third one with an empirical approach investigates how arbitrageurs exploit oracle vulnerabilities. Empirical research from the Oxford-Hainan Blockchain Research Institute, Singapore University of Technology and Design, and Delft University of Technology further contributed to this field of study. The first proposed BLOCKEYE, a device able to hunt attacks on DeFi and oracle manipulations, for which the research team had already presented some experimental results [85]. Using primary data, the second showed the deviance rates of four oracle services to enlighten the oracle's reliability and possible malfunctions [1]. Finally, the third investigates how arbitrageurs' activities can influence or manipulate price oracle data feeds [84]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Research Themes** & **Research Directions** & **Converging Studies** \\ \hline \multicolumn{3}{c}{**Oracle Architecture**} \\ \hline Oracle privacy and security & - & Identify and prevent oracle & \\  & malfunction & University of Colorado [72] \\ Oracle privacy and security & - & Ensure data confidentiality & Jiamusi University [73] \\  & - & Guarantee censorship resistance & Hong Kong University [74] \\  & & and limit downtime periods & \\ \hline Oracle pricing and fees & - & Oracle pricing techniques & Montana State University [75] \\  & - & Gas pricing reliability & University of Sfax [76] \\ \hline \multicolumn{3}{c}{**Oracle Problem**} \\ \hline Oracle as a legal actor & - & Define the relationship between & \\  & oracles and other parties & \\  & - & Define oracles’ responsibilities & Max-Planck Institute [30] \\ \hline Oracle auditing & - & Define the means to detect & University of Salamanca [78] \\  & & improperly designed oracles & John Carroll University [13,79] \\ \hline Trust model & - & Adapt a trust model design to & University of Verona [9] \\  & & specific blockchain applications & Khalifa University [6] \\ \hline \multicolumn{3}{c}{Incentive to cheat} & - & Define the nature and driver of \\  & & trust in digital economies & Chiba University of Technology [81] \\  & - & Develop means to prevent selfish & University of Dallas [80] \\  & & behavior & \\ \hline \hline \end{tabular}
\end{table}