What is a 51% attack?
Bitcoin, like any system, is not perfect. In this post it is about the 51% attack: what is it, what can it and how can you prevent it.
"Be your own bank!" - one of the best known slogans of the Bitcoin community. As a friend of a decentralized organization, somewhere between Belloc and Hughes, the slogan always appealed to me. Too often, however, one has the impression that such slogans like to make flutes, "all for all and for nothing". If we really want to decentralize the banking system, we must also decentralize the responsibility that lies in their hands. And this means that we can be not just users but enlightened, critical users who have an eye on the blockchain. We need to know the dangers, and know what signals are for an attack on the blockchain. Consider the 51% attack.
How does a 51% attack?
The Bitcoin infrastructure consists of the user (or more precisely his wallets), different user interfaces, the miners and the nodes. The nodes are responsible for maintaining the Bitcoin network and managing transaction traffic. Nodes guarantee that all transactions comply with the rules. The task of the Miner is finally to summarize transactions to blocks and attach them to the blockchain.
The infamous 51% attack is now the following scenario: let's say an attacker would manage to put over 50% of miners. If we look at blockchain.info, we can quickly see that three of the large mining pools (Antpool, F2Pool and Btcc Pool) have more than 50% of the hashrate. The concern is therefore not only purely hypothetical, but quite real. In other Altcoins sowas apparently ever happened.
So let's say the three mentioned mining pools are for what reasons together. What could they do?
To clarify this, let's go back to the Roots, to Satoshi Nakamotos Paper. In Section 11, he considers the problem when an attacker wants to feed false blocks into the system. Ultimately, one can calculate how likely it is that an attacker "gets his" blockchain.
Rplot04
In the above figures, this success probability is shown, to the left, depending on the relative hash rate of the attacker (assuming 6 acknowledgments of a transaction) and right, depending on the number of transactions (assuming a relative hash rate of 26% Attacker).
We quickly recognize that if the attacker's hashrate is greater than or equal to the opponent, the probability of changing things is equal to one. This means that someone with more than 50% of the Hashrates would have incredible power on his side; Above formula would always be decided in his favor. You should also have it in the back of the head: Even if the attack is 51% attack and suggests that you need more than fifty percent of the hashrates for the attack, you can see from the formula of Nakamoto that with a lesser control the probability of success Of an attack is simply smaller. Say: You should not just pull at the 51%, already with significantly less can one build a lot of crap.
Possibilities of the 51% apprentices
What could such an attacker do?
As long as he has control, he could perform double-spent transactions. More specifically, he could reverse transactions and transfer them elsewhere. This would, of course, completely destroy the Bitcoin ecosystem.
It could prevent as many transactions as possible or, more precisely, not guarantee them any confirmations. The attacker could specifically bspw certain payments and thus turn off individual companies.
It could block as many miners as possible from mine any valid blocks and mine the rewards themselves.
That is a lot! Accordingly, one should take the risk seriously.
What can you do about it?
The beautiful thing about the blockchain is that everything is transparent. We can observe the blockchain. Directly on Blockchain.info you can see which mining pools which blocks have found. This is, of course, not an "antidote", but it can help to recognize whether there are mining pools that significantly contribute a block of the blockchain.
Unfortunately, in the case of Bitcoin, it is difficult to do as an individual. One can not simply make sure that the "good" miners get a whole lot more hashing power. It was otherwise suggested to lure enemy miners through targeted DDoS attacks, which is also not trivial.
One thing, however, which can also do an Otto-Normal consumer in such a crisis case is that he increases the number of transactions of a transaction number to counter duplicate transactions. Should an attacker really 50%
"Be your own bank!" - one of the best known slogans of the Bitcoin community. As a friend of a decentralized organization, somewhere between Belloc and Hughes, the slogan always appealed to me. Too often, however, one has the impression that such slogans like to make flutes, "all for all and for nothing". If we really want to decentralize the banking system, we must also decentralize the responsibility that lies in their hands. And this means that we can be not just users but enlightened, critical users who have an eye on the blockchain. We need to know the dangers, and know what signals are for an attack on the blockchain. Consider the 51% attack.
How does a 51% attack?
The Bitcoin infrastructure consists of the user (or more precisely his wallets), different user interfaces, the miners and the nodes. The nodes are responsible for maintaining the Bitcoin network and managing transaction traffic. Nodes guarantee that all transactions comply with the rules. The task of the Miner is finally to summarize transactions to blocks and attach them to the blockchain.
The infamous 51% attack is now the following scenario: let's say an attacker would manage to put over 50% of miners. If we look at blockchain.info, we can quickly see that three of the large mining pools (Antpool, F2Pool and Btcc Pool) have more than 50% of the hashrate. The concern is therefore not only purely hypothetical, but quite real. In other Altcoins sowas apparently ever happened.
So let's say the three mentioned mining pools are for what reasons together. What could they do?
To clarify this, let's go back to the Roots, to Satoshi Nakamotos Paper. In Section 11, he considers the problem when an attacker wants to feed false blocks into the system. Ultimately, one can calculate how likely it is that an attacker "gets his" blockchain.
Rplot04
In the above figures, this success probability is shown, to the left, depending on the relative hash rate of the attacker (assuming 6 acknowledgments of a transaction) and right, depending on the number of transactions (assuming a relative hash rate of 26% Attacker).
We quickly recognize that if the attacker's hashrate is greater than or equal to the opponent, the probability of changing things is equal to one. This means that someone with more than 50% of the Hashrates would have incredible power on his side; Above formula would always be decided in his favor. You should also have it in the back of the head: Even if the attack is 51% attack and suggests that you need more than fifty percent of the hashrates for the attack, you can see from the formula of Nakamoto that with a lesser control the probability of success Of an attack is simply smaller. Say: You should not just pull at the 51%, already with significantly less can one build a lot of crap.
Possibilities of the 51% apprentices
What could such an attacker do?
As long as he has control, he could perform double-spent transactions. More specifically, he could reverse transactions and transfer them elsewhere. This would, of course, completely destroy the Bitcoin ecosystem.
It could prevent as many transactions as possible or, more precisely, not guarantee them any confirmations. The attacker could specifically bspw certain payments and thus turn off individual companies.
It could block as many miners as possible from mine any valid blocks and mine the rewards themselves.
That is a lot! Accordingly, one should take the risk seriously.
What can you do about it?
The beautiful thing about the blockchain is that everything is transparent. We can observe the blockchain. Directly on Blockchain.info you can see which mining pools which blocks have found. This is, of course, not an "antidote", but it can help to recognize whether there are mining pools that significantly contribute a block of the blockchain.
Unfortunately, in the case of Bitcoin, it is difficult to do as an individual. One can not simply make sure that the "good" miners get a whole lot more hashing power. It was otherwise suggested to lure enemy miners through targeted DDoS attacks, which is also not trivial.
One thing, however, which can also do an Otto-Normal consumer in such a crisis case is that he increases the number of transactions of a transaction number to counter duplicate transactions. Should an attacker really 50%
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