How to obtain trustworthy data is the solution that oracles need. To solve this problem, we need to make this data credible, we can imagine a process, for example, the boss wants to know what the employee's salary is, he will not ask the employee one by one, he will for example, find the salary of the financial department to give him the salary form of the employee last month, the salary form is reviewed by the personnel, finance, and business departments to give Xiao Zhang. In this process,

If the boss wants to ensure that the salary information obtained is accurate, he must meet two conditions, the first is that the data source itself is credible, and the salary form has indeed been reviewed by the personnel, finance, and business departments, and the second is that the reporter is credible, that is, Xiao Zhang is credible. Let's first look at how to ensure that the data source is credible, in this example, the payroll has been reviewed by multiple departments, and let's change to an example of the most common data on the chain, as we just mentioned, Ethereum is denominated against the US dollar, where is the data source? In centralized exchanges, these price information are stored in the servers of centralized exchanges, and the information on the server itself is not as secure and reliable as the blockchain, because as long as the service provider wants to tamper with it, they can directly set a price they want at any time. This means that Ethereum can't directly trust the data provided by a single service provider. Since you can't trust the data provided by a single service provider, wouldn't it be nice to have a few people, just like the multi-department audit in the example. Ask from centralized exchange A, and then ask from decentralized exchange B, anyway, as long as there are any, I will ask, and finally I do some data operations on them, such as removing a maximum value, removing a minimum value, and taking an average of the remaining prices, is it possible to get a relatively accurate price.

Then we need to ensure that the reporter is credible, that is, as the finance department, Xiao Zhang is credible, how to ensure that Xiao Zhang is credible? The answer is no, Xiao Zhang can never be trusted, because if Xiao Zhang, he directly took the highest value, or rather, he simply reported a number himself, and no one can point out his mistake, then it is equivalent to not asking, and the result may not be as reliable as taking the data directly from the centralized exchange. If one person can't ask, then we will add a few more people, we will let Xiao Zhang, Xiao Li, and Xiao Wang all ask again, and then let them if anyone gives the wrong price, all the wages will be deducted this month, to ensure that Xiao Zhang, Xiao Li and Xiao Wang, a small group of price feeding, can provide accurate data. The deduction of wages is equivalent to passing the consensus mechanism of PoS, ensuring that they will not do evil from the perspective of personal economic interests.

Okay, so now we have a relatively credible model of off-chain data acquisition, the blockchain trusts a decentralized price feed group, and there are many different nodes in the price feed group to form a PoS network, note that this is just a data service network, not a blockchain, to obtain off-chain data information from multiple trusted data sources, and finally feed the summarized data results to other smart contracts on the chain through smart contracts, realizing the closed loop of overall data reliability.

What does an oracle have to do with a bridge? In fact, in this model, if we change the last trusted data source from a server to another blockchain, will we be able to communicate the data of the two chains, so that the data of the two chains can interact with each other, so as to realize the interaction of some assets. The implementation of the specific cross-chain bridge is another big story, and we will continue to talk about it in detail in the next issue!

How to obtain trustworthy data is the solution that oracles need. To solve this problem, we need to make this data credible, we can imagine a process, for example, the boss wants to know what the employee's salary is, he will not ask the employee one by one, he will for example, find the salary of the financial department to give him the salary form of the employee last month, the salary form is reviewed by the personnel, finance, and business departments to give Xiao Zhang. In this process,

If the boss wants to ensure that the salary information obtained is accurate, he must meet two conditions, the first is that the data source itself is credible, and the salary form has indeed been reviewed by the personnel, finance, and business departments, and the second is that the reporter is credible, that is, Xiao Zhang is credible. Let's first look at how to ensure that the data source is credible, in this example, the payroll has been reviewed by multiple departments, and let's change to an example of the most common data on the chain, as we just mentioned, Ethereum is denominated against the US dollar, where is the data source? In centralized exchanges, these price information are stored in the servers of centralized exchanges, and the information on the server itself is not as secure and reliable as the blockchain, because as long as the service provider wants to tamper with it, they can directly set a price they want at any time. This means that Ethereum can't directly trust the data provided by a single service provider. Since you can't trust the data provided by a single service provider, wouldn't it be nice to have a few people, just like the multi-department audit in the example. Ask from centralized exchange A, and then ask from decentralized exchange B, anyway, as long as there are any, I will ask, and finally I do some data operations on them, such as removing a maximum value, removing a minimum value, and taking an average of the remaining prices, is it possible to get a relatively accurate price.

Then we need to ensure that the reporter is credible, that is, as the finance department, Xiao Zhang is credible, how to ensure that Xiao Zhang is credible? The answer is no, Xiao Zhang can never be trusted, because if Xiao Zhang, he directly took the highest value, or rather, he simply reported a number himself, and no one can point out his mistake, then it is equivalent to not asking, and the result may not be as reliable as taking the data directly from the centralized exchange. If one person can't ask, then we will add a few more people, we will let Xiao Zhang, Xiao Li, and Xiao Wang all ask again, and then let them if anyone gives the wrong price, all the wages will be deducted this month, to ensure that Xiao Zhang, Xiao Li and Xiao Wang, a small group of price feeding, can provide accurate data. The deduction of wages is equivalent to passing the consensus mechanism of PoS, ensuring that they will not do evil from the perspective of personal economic interests.

Okay, so now we have a relatively credible model of off-chain data acquisition, the blockchain trusts a decentralized price feed group, and there are many different nodes in the price feed group to form a PoS network, note that this is just a data service network, not a blockchain, to obtain off-chain data information from multiple trusted data sources, and finally feed the summarized data results to other smart contracts on the chain through smart contracts, realizing the closed loop of overall data reliability.

What does an oracle have to do with a bridge? In fact, in this model, if we change the last trusted data source from a server to another blockchain, will we be able to communicate the data of the two chains, so that the data of the two chains can interact with each other, so as to realize the interaction of some assets. The implementation of the specific cross-chain bridge is another big story, and we will continue to talk about it in detail in the next issue!