How to prevent fake data from being sent to a Blockchain

Question

I am developing a blockchain for IoT applications, where there are a number of gateways (miners) spread throughout the city and several nodes (sensors) connected to each of them. Each gateway can be added by an end user so this is a untrusted environment. How can I make sure that there isn't fake data being sent to the chain by one of the miners?

I have looked up some consensus protocols by find that none fit this specific problem since there is no value being exchanged.

Every miners sends a ping to a master server and receives from it the list of miners on the network. Then they connect to each other by p2p.

Any ideas of how could I solve this?

Answer 1

Blockchain can be used in both cases permission-less or permissionned, if you want to prevent that anyone can broadcast data, then you have to authenticate the nodes before they can join the network. If even after authenticating the nodes there is a chance that an authenticated node send "fake data" then a trust mechanism must be implemented, nodes verify the trustworthiness of the data's source and decide if the node is trusted and accept the data or not.

Answer 2

In order to prevent spamming or fake data being posted, it has to be added as a consensus rule to the protocol. Otherwise, it requires another layer that validates data based on off-chain data (but doesn't prevent data from being stored in blocks). Blockchain is for achieving distributed consensus, in a permission-less system. Restricting who can participate is not a permission-less system, and would be a centralized system because someone has to determine who is allowed to participate.

Answer 3

The answer to the query lies in Blockchain Oracles .

Oracles to-date are centralized services, meaning any smart contract using such services has a single point of failure, which nullifies any benefits gained from the decentralized nature of smart contracts.

To fill this gap, Chainlink was developed as the first decentralized oracle that can provide external data to smart contracts. As a result, the security and determinism of smart contracts can be combined with the knowledge and breadth of real-world external events. Chainlink will provide a smart contract with access to any external API needed.

As according to chainlink here and here

Blockchains and smart contracts cannot access data from outside of their network. In order to know what to do, a smart contract often needs access to information from the outside world that is relevant to the contractual agreement, in the form of electronic data, also referred to as oracles. These oracles are services that send and verify real world occurrences and submit this information to smart contracts, triggering state changes on the blockchain.