As reported recently by a user on Twitter, a hacker yesterday tried to transmit a block with only one 0, trying to fool the PoW (Proof of Work)
#bitcoin under attack:
twice someone tries to broadcast a bad block (proof of work failed: blocks start with only one zero .. 15 min later with not enough zero's).
Glad my node rejects this joker immediately! pic.twitter.com/3yPEsTp91J
— PlanB (@100trillionUSD) October 13, 2019
The message says that the error was found in the user’s node, which was built on a Raspberry Pi and using a 500GB SD card as storage, in order not to have problems with a 24/7 use.
But why is a block with only one 0 a problem for Bitcoin?
The Bitcoin blockchain uses the PoW (Proof of Work) consensus protocol. This protocol is used to find a string of code that starts with several 0s, about 19 zeros: these zeros represent the difficulty of the calculation and therefore the security of the transaction.
If a transaction has only one 0 or even just a couple, like in this case, it can be easily deduced that it took little time to calculate the hash and therefore there’s a 99% chance that it was an attempt to attack Bitcoin in order to push through a forged transaction.
Fortunately, the transaction was rejected by the node in question precisely because thensaction is cancelled.
This is a good example of how Bitcoin, and in this case, the PoW (Proof of Work) protocol, has proved to be resistant to any kind of attack, even different from the typical 51% attacks.
As energy-intensive as it may seem as a protocol, PoW is nothing more than the underlying, that is, the energy which can secure a blockchain.