Now, that we know about how the Blockchain works on an individual node, let's discuss how a network of nodes functions. On a very basic level, the whole blockchain just operates as a network of nodes that have some information or part of the blockchain.
Back To Real Estate
In my previous post here, I used an example of a govt. ledger that keeps track of houses. We had suggested that we should move the system to a blockchain. Let's say that someone decides to go through all of the trouble of computing the hash of each block. Then what is preventing them from changing the records? Well, as it turns out nothing much if the blockchain is only present on one node. Now, we will solve the problem using a system of peer-to-peer nodes.
How is the blockchain actually connected?
We will now distribute the blockchain over to a network. The network will be connected through cryptographic keys and stuff, so no one will know the actual data. Let's say that a block was added or mined on computer 1. Then, let's say that again some time passes.
Now, let's say that a bad actor has been able to successfully change a block on one of the nodes and has also gone through the trouble of recomputing the hashes. In our previous example, that would've been it. The blockchain would've been compromised.
How do we protect?
Thankfully, in a peer-to-peer network, the computers are all synced up in real-time. Therefore, they will try to match the block to validate the chain and when they find a mismatch. They will, in a symbolic manner, tell the node with the faulty chain that "Hey, your chain doesn't seem to be right."
This will cause the infected node to realise that it has been infected. Which in turn, causes the infected blockchain to copy over the values and correct itself. Also, you need to realise that all of this happens in a matter of milliseconds to minutes. So, the problem will be fixed even before bad actor gets to the end of the chain.
All of this is made even more difficult because there are thousands or millions of nodes on a popular network like the Bitcoin network. And the only way to do it is to gain access to more than 50% of the network and that too in a matter of seconds. This makes it nearly impossible to hijack a blockchain network.
This post, therefore, gives us an insight into how the network is secured and what it takes to be able to hijack a network. Which in itself is also pretty impossible.
Thanks for reading and see you in the next one!