Bitcoin Forum

what is an oracle in blockchain technology and how does it help to connect offchain data to onchain smart contracts ?

and, how does an oracle in blockchain ensure, that the external data it provides to smart contracts is trustworthy and reliable, without compromising the security of the blockchain network?

 smartcontracts running on blockchain cannot acces data outside of its blockchain.

An Oracle is a middleware which allows data from outside be used in the blockchain.
Usually,  those oracles have validators  (similart to bitcoin nodes) which validate external data.

Oracle doesn't check the trustworthiness of the information it provides, and even worse, it can lie on purpose or be manipulated into believing it reports correct information. In most cases, it just extracts data from the real world without conducting any fact-checking and then sends this directly into the blockchain. If data turns out to be incorrect or malicious, well, it is a terrible situation for people who rely on smart contracts to benefit from particular outcomes. How do you mitigate the risk of fake information? You employ several oracles from different vendors, written in different programming languages and using different algorithms for extracting information. If 9 out of 10 oracles tell you that something should be true, then it must be true, and you just ignore the 10th one.

The security depends on honestly of the oracle and soruce of the data itself. Some smart contract attempt to mitigate that by choosing some oracle which meet some condition (e.g. only masternode or anyone who stake at least X coin) and optionally punish oracle who give different data compared with all other oracles.

And since this question asked on Bitcoin board, FYI Bitcoin doesn't have smart contract capability.

Bitcoin supports Discreet Log Contracts (DLC), a simple form of oracle, just fine [1] [2].
DLC is a form of scriptless script, that only needs Schnorr signatures to implement.

[1] https://dci.mit.edu/smart-contracts

[2] https://medium.com/interdax/discreet-log-contracts-smart-contracts-for-bitcoin-d75f22d25dac

An oracle is like a messenger between the real world and a blockchain. It provides information from the real world to the blockchain, such as the final score of a sports game. This information can then be used by a smart contract to trigger a specific action, such as automatically paying out winnings to people who bet on the winning team.

In blockchain technology, an oracle is a well trusted third-party service or an agent that provides a off-chain data to on- chain smart contracts. and also Oracles enable smart contracts to interact with real-world data, such as stock prices, weather conditions, or even sport scores, which are not available on blockchain.

I think oracles can also pose security risks to your blockchain network if they are compromised or maliciously manipulated. Therefore, it is crucial to ensure that oracles are trustworthy and reliable and your data is verifiable and auditable.

If you are still curious or willing to learn, some of the links are not working anymore so im just gonna drop that is working.
https://blockgeeks.com/guides/blockchain-oracles/ (https://blockgeeks.com/guides/blockchain-oracles/)