Topic: Need an explanation over 51% attack. - page 2. (Read 615 times)

More Bitcoins being mined doesn't mean that it would be more susceptible to a 51% attack.

If Bitcoin becomes more expensive, it would be a possibility. They would be able to get a larger profit of fiat if they execute a 51% attack for the same amount of Bitcoins. The main factor affecting the cost of Bitcoin is the network's hashrate. If more people are mining, it is harder for anyone to be able to control 51% of the network as it would require more hashrate and money.

So, this means that as more bitcoins are mined, and if bitcoin price keeps growing, a 51% attack is more unlikely because it becomes more expensive right?

51% can be used to rewrite history, but this kind of attack become more and more expensive depending on how many blocks you have to rewrite.
if you want to doublespend a transaction with 3 confirmations you have to find 4 blocks if you want to doublespend a transaction with 6 confirmations you have to find 7 consecutive blocks. If you only have 51% you will find a block approx each 19 minutes. this make doublespending very expensive, and likely non profitable.

from what I know pow will survive to quantum computers, difficulty will adjust to have a block each 10 minutes.



this is false. ripmed offer e very strong protection for your coins. to be safe simply do not reuse addresses.

I think it's important to point out that the big problem with 51% attacks is when they can effectively use this premise in the generation of new blocks to deceive exchanges with Double-spending. Increasing the number of confirmations can make such an attack difficult, even so, if someone controls> 50% it could still succeed regardless of the number of confirmations required.

In the beginning, there was a kind of signal that was sent to the devs when a problem occurred. Nowadays I do not know how the exchanges would be alerted. I think Bitcoin is the only project where the devs have no direct contact with the exchanges. And that's good. It proves that decentralization is sufficient thus far to ensure network security.

When you have more than 50% of the hashrate, you make more than 50% of the blocks. That means, your chain of blocks will always been the longest. Since the network generally trusts the longest chain, the blocks of all other miners can't compete against you. Therefore you can manipulate the chain long enough to fabricate your own transaction history and trick nodes into thinking that an amount you already spend is still unspend and thus you can run a double-spend attack (the very thing the blockchain is supposed to prevent).

The network is still decentralized but in a dysfunctional way, means your miner will control the whole blockchain no matter what everyone else on the network claims.

Quantum computers can run multiple guesses parallel and that enables them to guess a private key to an address with no effort at all. If quantum computers exist, all hashing and encryption methods that are industry standard today become useless. However when that happens, we need quantum resistant algorithms anyhow everywhere on the internet and Bitcoin can implement one of these algorithms too. Quantum computers can steal your coins by just guessing your private key if they know your public address, since every public address is generated from a private key. It's an one-way function that means, calculating a public key from a private is simple but the other way around is extremely difficult, however quantum computers can do it by just trying in literally no-time.

It's centralised as any entity controlling over 50% of the network's hashing power will be able to generate blocks faster than anyone else and hence no one would have a chance to get any blocks against them. This doesn't allow them to violate any protocol rules. Bitcoin functions on trusting the longest valid chain as the main chain and disregarding any other. As a result, they can potentially spend a coin twice by making nodes discarding the chain with the original transaction in and including the chain with their own transaction that spends the same inputs.
No 51% attacks has happened on Bitcoin.
No.
Not exactly. Anyone with a quantum computers can crack public keys within a reasonable timeframe but they are only exposed when UTXOs are being spent. If you just send Bitcoins to an address that has never been used, it is not possible for anyone to steal your coins with a quantum computer.

As we've been discussing things about Bitcoins, I'd like to know more (or I'd say an in-depth as well as detailed) analysis about the 51% attack. Can anyone here explain me that how it could actually affect the whole network and how it makes the whole thing centralized? The times when we witnessed even $100 as transaction fees should be considered as such attacks only that might have taken place to rise the value of fees to such incredible levels? Is there anything to prevent such attacks when quantum computing takes place? I know that quantum computing will just give the power to the institution to grab the privkeys directly, still if they want to go the ^legal^ way, can they ruin it for everyone?