The question now is ‘how does proof-of-work create immutability and tamper-proofing?’
Well, let us assume you gain more than 51% control of the validators (which is impossible as there are millions of nodes in a blockchain and keep increasing every second). After gaining control you can theoretically do two things,
- You can control the publishing of the future blocks as you have majority control over validation (miners). And;
- You can attempt to change the blocks of the past (the ones already published).
Here is why it is impossible to change the blocks of the past.
When you gain the control over the majority of the validation process, you will go back in the chain and change the contents of a particular block. Now, when this block is changed you will approve it’s validity as you have major control and also, you will commit energy resources to the block.
Since you will now have to publish a new block with a new 64 digit hash, for all the blocks that existed, after the one you just changed, you will have to employ un-imaginable amounts of energy just to reach the present block.
Also, you will have to incentivise the miners to validate the blocks which will turn out to be extremely expensive.
And on top of that, while you perform this time consuming activity, new blocks will be published by the other participants of the blockchain for their personal transactions. Therefore you will have to catch-up with the, then present block by employing more energy and monetary resources.
It is too much for too little.
This is what makes blockchain a ‘tamper-proof’ technology.
P.S. To know about proof-of-work click here. Happy reading!