Unlocking the Mysteries of Blockchain Oracles

An oracle is a third-party service that allows a smart contract to retrieve data from a remote source.

One of the most challenging aspects of blockchain governance is separating off-chain and on-chain data. An oracle is a useful tool for linking real-world information with blockchain activity. Users can use blockchains in a variety of ways in their daily lives thanks to Blockchain Oracles.

Let’s learn more about this fascinating topic and the crucial issues surrounding it in this blog.

Blockchain Oracles Explained

Blockchain oracles refer to third-party services that furnish external information to smart contracts. They act as connectors between blockchains and the external environment.

Blockchains and smart contracts are unable to access data that exists beyond their networks, known as off-chain data. Nevertheless, for numerous contractual arrangements, it is crucial to incorporate pertinent external information for contract execution.

Blockchain Oracles Working
Blockchain oracles step in to address this need, facilitating the linkage between off-chain and on-chain data. Oracles play a vital role in the blockchain ecosystem by expanding the capabilities of smart contracts. In their absence, smart contracts would be severely limited, only able to access data within their own networks.

It’s essential to understand that a blockchain oracle doesn’t serve as the data source itself; instead, it functions as an intermediary layer that queries, validates, and authorizes external data sources before transmitting that information. Oracles transmit various forms of data, such as price data, payment completion status, or sensor-recorded temperatures.

To access data from the external world, a smart contract must be invoked, and network resources must be expended. Some oracles not only relay information to smart contracts but can also send data back to external sources.

Understanding Blockchain Oracles With an Example

Imagine a scenario where Pramod and Umesh make a bet on the outcome of the Indian presidential election. Pramod predicts the BJP candidate will win, while Umesh bets on the Congress Candidate. They establish the terms of their bet and lock their funds into a smart contract. This contract will distribute all the funds to the winner based on the election results.

Because the smart contract lacks the ability to interact with external data sources, it relies on an oracle to provide essential information. Following the election’s conclusion, the oracle queries a trusted API to determine the victorious candidate and conveys this data to the smart contract. Subsequently, the contract disburses the funds to either Pramod or Umesh, depending on the election’s outcome.

In the absence of the oracle transmitting this data, there would have been no reliable way to resolve the bet, preventing potential manipulation by either participant.

What Kinds of Blockchain Oracles Exist?

Blockchain oracles can be categorized based on several key attributes:

▪️ Origin: Does the data source originate from software or hardware?

▪️ Information Flow: Is it inbound (to the blockchain) or outbound (from the blockchain)?

▪️ Trust Model: Is it centralized or decentralized?

It’s possible for a single oracle to fit into multiple categories. For instance, an oracle that retrieves data from a company’s website can be classified as a centralized inbound software oracle.

Different Types of Blockchain Oracles

◾Software Oracles: These oracles interact with online data sources and relay that data to the blockchain. They can source information from various online platforms, including databases, servers, and websites, making them a prevalent type of blockchain oracle. Common data provided by software oracles includes exchange rates, digital asset prices, and real-time flight details.

◾Hardware Oracles: In some cases, smart contracts require real-world information. Hardware oracles are designed to extract data from physical sources, such as electronic sensors and barcode scanners, and make them accessible to smart contracts. 

Essentially, they translate real-world events into digital values that smart contracts can understand. For example, a sensor can inform a smart contract when a truck arrives at a loading bay, allowing the contract to take action accordingly.

◾Inbound and Outbound Oracles: Inbound oracles convey external data to smart contracts, while outbound oracles transmit information from smart contracts to the external world. For instance, an inbound oracle might report the temperature measured by a sensor to a smart contract, while an outbound oracle could unlock a smart lock when funds are deposited to a specified address.

◾Centralized and Decentralized Oracles: Centralized oracles are controlled by a single entity and serve as the sole data source for smart contracts. Relying on a single source can be risky due to the potential for manipulation and the presence of a single point of failure. 

Decentralized oracles, on the other hand, aim to enhance reliability by aggregating information from multiple sources, often referred to as consensus oracles. This approach reduces counterparty risk and is particularly valuable in prediction markets and applications where social consensus verifies outcomes.

◾Contract-Specific Oracles: A contract-specific oracle is tailored for use by a single smart contract. While this provides flexibility for specific use cases, it can be resource-intensive and impractical when dealing with multiple smart contracts. Developing and maintaining multiple contract-specific oracles can be challenging.

◾Human Oracles: In some cases, individuals with specialized knowledge in specific fields can act as oracles. They research and validate information from various sources, translating it for smart contracts. Human oracles can use cryptographic verification to enhance trust and reduce the risk of fraudulent data input.

The Oracle Issue

Smart contracts play a crucial role in maintaining a healthy blockchain ecosystem because they execute decisions based on data from oracles. However, a significant challenge in Oracle design lies in the fact that if an Oracle is compromised, it can compromise the smart contract it supports, commonly known as The Oracle Problem.

Unfortunately, oracles do not participate in the primary blockchain consensus, which means they lack the security mechanisms inherent in public blockchains. This results in an unresolved trust conflict between third-party oracles and the trustless execution of smart contracts.

Additionally, there is the risk of man-in-the-middle attacks, where malicious actors intercept and manipulate the data flow between oracles and contracts, posing a serious threat to the integrity of the data.


Ensuring global blockchain adoption requires a dependable system for smart contracts to interact with external data, highlighting the significance of blockchain oracles. Without them, smart contracts would be restricted to internal data, severely constraining their functionality.

The implementation of decentralized oracles holds the promise of enhancing the safety of the blockchain ecosystem by mitigating systemic risks. Achieving a secure, trustworthy, and reliable implementation of blockchain oracles is pivotal for the growth of the blockchain ecosystem.

To learn more about Blockchain Oracles, go check out SunCrypto Academy.

Disclaimer: Crypto products and NFTs are unregulated and can be highly risky. There may be no regulatory recourse for any loss from such transactions. All content provided is for informational purposes only, and shall not be relied upon as financial/investment advice. Opinions shared, if any, are only shared for information and education purposes. Although the best efforts have been made to ensure all information is accurate and up to date, occasionally unintended errors or misprints may occur. We recommend you please do your own research or consult an expert before making any investment decision. You may write to us at [email protected].

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