CAN QUANTUM COMPUTING HACK BITCOIN?

When can a quantum computer hack or break bitcoin or can it even do that at all and if it can when should we really start worrying. Quantum computing's potential impact on bitcoin and other cryptocurrencies.

There's two things that people are mostly concerned about one is the mining and the other is the spending.

First what the blockchain is and how bitcoins are actually mined. The blockchain is an online decentralized public ledger that records transactions throughout a network. A group of approved transactions is called a block and these blocks are tied together hence the term blockchain. Since this ledger is public and anyone can see it. It serves to confirm that transactions actually happened and this prevents double spending of the coins.

Mining is something that is used to introduce bitcoins into the system. There's a hard cap of 21 million bitcoin throughout the entire system and as of today there's only about 10 percent of that bitcoin remaining to be mined and this mining is designed to be really resource-intensive and difficult to do so the number of bitcoins that are mine every day remains steady

 

How does mining work

Sha 256 is a cryptographic hash function and what it does is it takes an input and produces an output of fixed size. Hash functions are really powerful, but it's very hard to reconstruct that message just given the output simply. what we need to do to actually mine. the header block is an 80-byte long string it has a bitcoin version number the previous block hash a Merkle root the long timestamp of the block a difficulty target for the block and a nonce to mine we increment the nonce and then hash the block header and compare that hash to the target if the hash is less than the target then we win and we mine the block so the point here is to mine bitcoin faster.

 

Can quantum computers actually help with that since quantum computers do not brute force or parallelize finding the nons we need to see if there's a quantum algorithm that can actually undo this hash and as of right now there's no known quantum algorithm that can actually undo the Sha-256 hash function so unfortunately a quantum computer can't help. Bitcoin is something that is designed to adjust the difficulty if we mine blocks to fasts. Also if we found the quantum algorithm, the difficulty would just get harder. The goal rate is to mine one block every 10 minutes and this rate is recalculated every 2016 blocks to make sure it remains at the same rate. It means that if we did have a quantum algorithm mining with a quantum computer would be a lot more effective so you wouldn't actually get more bitcoin faster but people with a classical computer would not have the same advantages that a quantum algorithm would have. It would really depend on the quantum algorithm and the speed up and this is really why mining with a computer or CPU right now is not really that practical that's because people are mining with Asics that are already sued for this bitcoin problem which means they're more likely to win.