Basics of blockchain

LIKE a lot of complex technologies, blockchain is easier to understand once you break it down.

A blockchain is made up of a block of “transaction data” which is why it’s also called a ledger. Each block also has a hash – a string of numbers which uniquely identifies the block.

And similar to how a person has their parent’s names added to theirs, a block features a portion of the preceding block’s hash.

Put in terms of family lines, it’s like how you could tell that Amir bin Ali is the son of Ali bin Abu, who is in turn the son of Abu bin Bakar, and so on.

Basically, the hash “chains” the blocks together, by affirming their place in relation to the blocks before and after, hence the term blockchain.

Security in numbers

A key feature of blockchain is security. Blockchain runs on the paraphrased adage that you can fool some of the people some of the time, but not all the people all the time.

So rather than making it ­tamper-proof, blockchain is ­tamper-evident – this is done by making a copy of the blockchain available to all members of the network, which is why blockchain is sometimes referred to as a ­public ledger.

As members of the network all have a copy of the same ­blockchain, if anyone’s chain is compromised by a hacker, it would look different from others.

If you have ever tried to organise a movie night with an extended group of friends on a WhatsApp group, you’ll get the idea.

Say, you want to watch Marvel’s Avengers: Infinity War and get the ball rolling by choosing the day and cinema, and then ask whoever that’s interested to add their names to the list.

The original message can’t be altered as it has been sent to the group. Instead everyone adds to the data by including their names and maybe a request for a specific timeslot. This concept is called “persistence”, wherein the older data cannot be retroactively altered.

Though a cheeky friend could change the date to try to troll the group, he wouldn’t be able to hide the fact that earlier messages will show a different date. This is what makes a public ledger like the blockchain tamper-evident.