The mechanism for writing information outside the blockchain to the blockchain is called a oracle. For example, if you write a smart contract, if you get wet tomorrow, you will give me a dollar, otherwise I will give you a dollar. Smart contracts are on the blockchain, so whether this rainy data needs to be read from the outside with a predictor. In other words, the prophecy is the bridge between the blockchain and the real world.
What is the prophecy machine?
The prophecy is not a predictive market, it is not a mechanism for everyone to vote to determine the authenticity of a thing. Some oracles only read data from a single API, so the ultimate security of the smart contract is attributed to a centralized organization.
This is reminiscent of the application of blockchain deposit. The blockchain itself can guarantee that the data cannot be tampered with. There is currently no good way to guarantee the authenticity of the information stored. The basic idea of some blockchain deposits is this, that is, cooperation with centralized authorities. For example, if this information is deposited by the public security agency, it is considered to be valid. This kind of thinking, Peter personally believes that it is also of practical value, after all, the use of the blockchain's untamed features. Of course, the biggest power is still in the hands of the centralized organization, and the "consensus determines everything, the market determines everything" is not in line with the blockchain.
To sum up, the security of the data read by the current oracle or blockchain is compromised with a certain degree of security.
Implement decentralized data on the link?
How to use decentralized ideas to ensure the authenticity of the data?
One of Peter's own ideas and friends is to read data from hundreds of disparate APIs or hardware sensors, and then cross-correlate to get the truth of the matter. With the development of the Internet of Things in the future, this idea is still possible. Andreas has had similar discussions .
In short, decentralized data uplinks are more feasible after human society has become digitally tenfold.
Thinking about smart contracts?
The problem of secure data uplink is a big bottleneck in the development of blockchain. This fact can help us understand such phenomena.
First, why blockchain smart contracts are currently only available to real users in the gaming category. Because the real world and blockchain are two almost isolated worlds. The biggest advantage of the blockchain is the fair random number and the chain of assets, so if you go to the betting game of the chain assets, this is still feasible.
Second, why do large companies engage in more alliance chains. Since the public chain is still connected to the physical world, it still depends on the data of the central authority to make the oracle input, then the complete decentralization seems to be of little significance. Then the idea of a coalition chain is simply to make the node into a real-name system. It is not unreasonable to use the credit of a big company to endorse the data on the chain. Although for ordinary people, these alliance chains are not much different from the databases of large companies, the blockchain allows certain data sharing and mutual trust between major companies, and it makes sense in many scenarios.
In short, every bit of progress in smart contracts is slow and arduous.
to sum up
Finally, summarize it. The prophecy mechanism is a mechanism that passes real-world data to the blockchain in order to make smart contracts work reliably. Safe and reliable data is very challenging.