Oracles: Everything to Know

By  Beluga Research August 5, 2023

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  • Cryptocurrency "oracles" are systems designed to provide real-world data to smart contracts.
  • Oracles bridge the gap between blockchains and the real world by collecting and verifying external data.
  • To maintain accuracy and security, decentralized oracles use multiple data sources and consensus mechanisms.
  • Oracles enable DeFi applications by providing access to real-time market data.


Cryptocurrency "oracles" are systems that provide real-world data to smart contracts, enabling them to interact with external information sources. Cryptocurrencies such as bitcoin and ether operate within closed systems wherein all the data and transactions are recorded on the blockchain. However, these closed systems lack access to information from the outside world, which limits the ability to interact with real-world events and data. This is where oracles are useful.

A Brief History

The concept of oracles in the context of blockchain technology traces back to the early days of smart contracts on the Ethereum network. Vitalik Buterin, the co-founder of Ethereum, first introduced the concept in a white paper in 2014. The idea was to create a mechanism that enabled smart contracts to interact with external data, making them more versatile and powerful.

Oracles: Everything to Know

In the context of cryptocurrencies, an oracle can be defined as a bridge between the blockchain and the real world. It is a software or hardware mechanism that retrieves and verifies external data and feeds it into the blockchain for consumption by smart contracts or dapps. Oracles essentially act as trusted intermediaries, ensuring that the data they provide is accurate and tamper-proof.

There are two main types of oracles: "Software oracles" and "hardware oracles." Software oracles are typically implemented as smart contracts on the blockchain, while hardware oracles rely on external devices or specialized hardware to fetch and transmit data. Both types have specific advantages and use cases.

The primary function of an oracle is to fetch and deliver external data to the blockchain. This data can be diverse and range from simple price feeds, weather conditions or sports scores to more complex information like election results or flight delays. Oracles retrieve this data by way of application programming interfaces (APIs), extraction from websites (known as "web scraping"), data transmitters known as "IoT devices" or even manual input, depending on the use case.

Data integrity and security are critical aspects of oracles. Since the blockchain is designed to be immutable and transparent, any inaccurate or malicious data injected into the system can have far-reaching consequences. To mitigate this risk, oracles employ different techniques such as data aggregation, multiple data source verification and consensus algorithms to ensure the accuracy and reliability of the provided data.

Oracles also play a vital role in enabling decentralized finance (DeFi) applications. DeFi aims to recreate traditional financial systems using blockchain technology, but it requires access to real-time market data such as asset prices, interest rates and exchange rates. Oracles facilitate this by collecting data from various sources and inserting it into DeFi protocols, enabling functionalities like decentralized lending, stablecoins and decentralized exchanges.

However, oracles are not without challenges. One of the significant concerns regarding oracles is the trustworthiness of the data they provide. Since oracles rely on external sources, there is always a risk of malicious actors manipulating or providing false information. This issue is known as the "oracle problem." Several potential solutions such as reputation systems, staking mechanisms and data verification are being explored to address this challenge and enhance the trustworthiness of oracles.

Getting Started

To understand how cryptocurrency oracles work, it is essential to grasp the basic principles of smart contracts. Smart contracts are self-executing agreements with predefined rules encoded on the blockchain. They automatically execute actions when specific conditions are met. However, smart contracts lack direct access to external data sources, such as stock prices, weather conditions or sports scores. This is where oracles come in.

Oracles act as intermediaries between the blockchain and external data sources. They fetch off-chain data and deliver it to smart contracts, enabling them to make informed decisions and perform actions based on real-world events. Oracles can retrieve data using various methods, including APIs, IoT devices, web scraping and even other blockchains.

When a smart contract requires external data, it sends a request to an oracle. The oracle then retrieves the requested data and verifies its authenticity and integrity. Once validated, the oracle relays the data back to the smart contract, which can then proceed with its execution based on the received information. This interaction allows blockchain applications to interact with the outside world in a secure and trustless manner.

Unique Aspects

One of the critical aspects of oracles is the ability to provide reliable and accurate data to smart contracts. Data integrity is crucial, as any tampering or manipulation could lead to incorrect outcomes and potential vulnerabilities. To ensure data accuracy, oracles use various techniques such as cryptographic proofs, consensus mechanisms and reputation systems.

Cryptographic proofs such as zero-knowledge proofs or digital signatures can be employed to verify the authenticity of the data retrieved by oracles. These proofs provide mathematical evidence that the data has not been tampered with during transmission. By including cryptographic proofs in the data transmission process, oracles can provide strong guarantees of data integrity, enhancing the trustworthiness of the overall system.

Consensus mechanisms are another key aspect of cryptocurrency oracles. Multiple oracles can be involved in fetching and validating data, and they can use consensus algorithms to agree on the accuracy of the information. This consensus ensures that the data provided by oracles is consistent and reduces the risk of single points of failure or malicious behavior.

Furthermore, reputation systems can be implemented to assess the reliability and performance of oracles. These systems track the historical behavior of oracles, taking into account factors such as data accuracy, response time and overall reliability. By assigning reputation scores to oracles, users can choose to rely on those with proven track records, minimizing the risk of receiving inaccurate or manipulated data.


  • Enhanced Functionality - Cryptocurrency oracles enable smart contracts to access and process real-world data, expanding the functionality of the systems beyond the confines of the blockchain. This opens up a wide range of possibilities for dapps to interact with external systems and respond to real-time events.
  • Real-Time Data - Oracles provide access to real-time data, allowing smart contracts to respond quickly to changing conditions. This is particularly valuable for applications that require up-to-date information such as financial services, supply chain management and decentralized exchanges.
  • Interoperability - By connecting blockchain networks with external data sources, oracles enhance interoperability between different platforms. They enable data and value transfer between disparate systems, fostering a more connected and seamless ecosystem.
  • Access to Off-Chain Data - Cryptocurrency oracles facilitate the integration of off-chain data into smart contracts. This is crucial for applications that rely on real-world information such as weather conditions, stock prices, sports scores and more. By accessing off-chain data, smart contracts can execute actions based on real-time events.
  • Decentralization - Many cryptocurrency oracles are designed to operate in a decentralized manner, leveraging multiple data sources and validators. This helps to ensure the reliability and integrity of the data provided, as it is not dependent on a single centralized entity. Decentralization reduces the risk of data manipulation or censorship, enhancing the trustworthiness of smart contract outcomes.


  • Data Source Reliability - The reliability of cryptocurrency oracles relies heavily on the accuracy and integrity of the data sources to which they are connected. If the data source itself is compromised or provides inaccurate information, it can lead to incorrect outcomes in smart contracts. Ensuring the reliability and authenticity of data sources is a crucial challenge for the oracle ecosystem.
  • Single Point of Failure - While decentralization is a key advantage of some cryptocurrency oracles, others may rely on a single provider or a limited number of validators. In these cases, if the oracle experiences downtime or becomes compromised, it can disrupt the functioning of dependent smart contracts, potentially causing financial losses or system failures.
  • Manipulation Risks - Cryptocurrency oracles can be vulnerable to manipulation, especially if they rely on a small number of data sources or validators. Malicious actors may attempt to manipulate the data provided to trigger actions that benefit them. This risk highlights the importance of designing robust oracle systems that incorporate multiple sources and employ mechanisms to detect and prevent manipulation.
  • Cost - The cost of utilizing cryptocurrency oracles can be a significant factor, as it depends on the complexity and frequency of data required. Accessing real-time data from premium sources or processing large volumes of information can incur substantial fees. This cost consideration should be weighed against the benefits and value provided by the oracle service.
  • Privacy - When integrating external data into smart contracts through oracles, privacy concerns may arise. The transparency of blockchain networks can potentially expose sensitive or proprietary data to the public. Therefore, care must be taken to ensure that privacy measures are implemented appropriately, such as utilizing secure data transmission protocols or employing encryption techniques.