Questions tagged [majority-attack]

A majority attack, or 51% attack, is an attempt at solo-mining a longer chain to outpace the main chain.

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Is it practical to prevent a 51%-attack by having a second mining algorithm?

While miners use special hardware designed to perform only one job (e.g. calculating sha256) changing that job would make all that hardware useless. So, can the bitcoin community use this ...
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Can miners single handedly perform 51 attack toward the network?

Is this true that miners alone cannot do 51 attack even one or a group of miners posses >51 percentage of hashrate of the network? As far as I know, every block should be accepted by nodes to be ...
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If the longest chain is considered the valid blockchain by nodes, what happens if a future supercomputer alters the entire blockchain?

Let's say that the computational power from the genesis block to the current block becomes a trivial computation in the future by some supercomputer using a new technology exclusive to it. Perhaps ...
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51% attack on a small network of nodes?

Not all the nodes in the bitcoin network are connected. So that means the computational power required to attack a smaller network would be comparatively easier. So, say we start a 51% attack on a ...
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Why wouldn't a state level actor be able to centralize Bitcoin?

I was reading this question: What can an attacker with 51% of hash power do? According to that, the 3 "powers" obtained through controlling 51% or more would be: Reverse transactions that ...
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Do nodes receive information from which they can discern how long a miner has withheld publishing a block from the time it found it?

In a recently Medium article, Joe Kelly described an attack that he calls "Monopoly Mining" in which a state actor or some other very well resourced party that obtains majority hashpower ...
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Can a 'China' or similar actor with more than half of the hash power really destroy Bitcoin?

More of a general question as I've recently gotten into investing in cryptocurrencies. I really love the vision for the future this technology provides, the freedom, ease of use, lack of middlemen, ...
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Would AsicBoost have made "all the difference between a profitable and an unprofitable mine" "for the bitcoin mines of the future"?

Back when AsicBoost was a thing - the paper by Timo Hanke, "AsicBoost - A Speedup for Bitcoin Mining", made the following claims in the introduction: Through gate count reduction on the ...
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How much hash power exists in redundant mining hardware?

I'm trying to understand the feasibilty of a hostile nation-state performing a double spend attack on bitcoin. Assuming mining profitability is not a concern, I wonder if they could buy or borrow ...
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51% attack inevitable [closed]

I think the assumption of a 51% attack is not worth the effort is wrong. Eventually the price of Bitcoin will stabilize. Let’s say at 1 million USD then a diminishing block reward and the transaction ...
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Noob question: Why is there not a limit of the number of blocks in a chain revision?

I have a noob idea and I want to understand where I'm going wrong :) Say nodes agreed on a block revision limit, say, 6. This would mean that if they see an incoming chain that is longer than the ...
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Can a 51% attacker earn mining rewards on the blocks they tampered with?

This article gives an example of a 51% attack in theory as: In a 51% attack the hacker will typically mine in private to attain a longer chain than the publicly seen chain in hopes of double-spending ...
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51% attack, miners, nodes or both

If 51% of the hashrate was controlled by bad actors mining invalid blocks, this would become the longest chain. Where do nodes come into the 51% attack? The canonical chain is the longest chain. Is ...
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Pissing Attack / adversarial blocks attack

How do the ones of you familiar with the protocol and game theory suggest dealing with potential 'empty block attacks' (a majority of miners collaborate to slow down Bitcoin transactions by producing ...
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How does the bitcoin core protect against initial DNS seed changes?

While the bitcoin network is essentially P2P, one still needs to identify an initial node to connect to. I understand that a method for such initial connections is connecting to known DNS seeds, e.g ...
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Miners forego revenue in order to 51% attack the Bitcoin protocol by rejecting blocks

I was recently listening to Mike Green and Anthony Pompliano debate the future of Bitcoin on RealVision. And Mike raised an interesting point regarding Bitcoin (I'm paraphrasing). "Scenario: Let'...
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Can the 51% attack be made to become 81% attack or 91% attack?

Since the 51% attack happens if there are more than 50% of nodes that fake the data on the blockchain, can it be actually 81% or 91% that is needed to fake the data, because it would be much harder if ...
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Why can't a 51% attack change past blocks on the blockchain?

I have read that it is not possible to reverse transactions already added to the blockchain but I do not understand why that is not possible in a 51% attack. If an attacker was to change the ...
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Did Satoshi Nakamoto (in his blogs or the whitepaper) forecast that mining pools would exist?

Mining pools are common today where users pool their resources together and share profits accordingly. Such pools today can account for significant proportions of a network's hash power and they're ...
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What will happen on creating a transaction with negative amount?

Bitcoin in short is a public ledger guided by consensus of its nodes. In theory, if there is no validation of transaction amount, if we were to create a transaction with negative amount, that would ...
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What are the benefit of mining an empty block

Something peculiar just happened on the newly mined block number 655534, it contain only the coinbase transaction, nothing else. I have searched for a similar question but only found this one Why ...
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How can Forks and Orphan Blocks be used to attack a Blockchain?

So I'm trying to learn about the security aspects of Blockchains and one of the papers I'm reading (https://arxiv.org/pdf/1904.03487.pdf) states that Forks and Orphaned Blocks can be used to attack a ...
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Attacker Changing Address to Receive Block Reward [duplicate]

A miner creates a block B which contains address α, on which he wants to receive his rewards. An attacker changes block B, such that instead of α it defines a new address α’, which is controlled by ...
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Two threats to Bitcoin: Quantum Computing and Mining farm seizures - what new BIPs are needed before it is too late? [closed]

How resistant is bitcoin blockchain against physical attacks? Contrary to other consensus mechanisms, Bitcoin's PoW model is dependent on massive Mining Farms with tons of ASIIC hardware. These farms ...
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How does longest chain propagation take place in bitcoin?

Let's say the valid blockchain that Node A has is: B1->B2->B3 Now, I am gonna cheat since I have lots of computing power. What I do is I download the above blockchain that Node A has and start ...
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Reversing network hashpower

I'm reading this article by Vitalik Buterin on Problems in Cryptocurrency and don't quite understand what this means: Ideally, after some number of blocks (perhaps logarithmic in the total size of ...
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Why is a 51% attack guaranteed to outpace the rest of the network's miners? Doesn't 51% hashing power give only a slightly higher chance?

I thought hashing power is an expression of the probability of being the one to solve the cryptographic puzzle and placing a new block on the network. If that's true, owning 51% of the hashing power ...
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the client's 'invalidateblock' debugging command - possible prevention against majority attack?

there is a 'invalidateblock' debugging command in the btc client. How can this command be used in a situation of majority attack threat and play a part of countering the attack? I understand that ...
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Incentive for miners to keep mining once reward get very low [duplicate]

Currently each winning miner receive 12.5 bitcoin or 12.5*10 000 dollar per successfully mined block and the amount of bitcoin receive is divided by 2 approximately each 4 years. The incentive to ...
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What are some potential scenarios that a state actor can harm bitcoin if they control more than 51% of the hashing power?

As reported recently, China controls more than 51% of the hashing power and just in one province in China controls 54%. Assuming China has bad intentions and forces all these mining operators to ...
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Can attackers change transactions during a 51% attack?

If in a 51% attack transactions can be reversed, isn't it possible that the chain with more hash rate also changes transactions (for example if x sent 5 btc to y, they would change it to x sent 500 ...
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transactions and 51% attack?

I have a very basic understanding of how the bitcoin blockchain works and am trying to understand how manipulating transactions in a 51% attack works. I just watched a video which stated 51% attacks ...
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Can collective mining pools refuse to recognize a mining block mined by a specific miner?

This is a continuation to the question: Can a bitcoin transaction from a specific bitcoin address be banned? (via mining pools). Suppose Satoshi Nakamoto sends bitcoins from one address to another, ...
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Bitcoin 51% majority miner attack - question on the role of user activated soft forks as defense tactic

If one mining entity has alone 52% hash power of the overall network, then this party can block transactions for example and try to "build" up a forked, longer chain while time passes, right?. As I ...
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Can a bitcoin transaction from a specific bitcoin address be banned? (via mining pools)

Can a bitcoin transaction from a specific bitcoin address be banned? (via mining pools) Suppose Satoshi Nakamoto wants to send some bitcoin from one of his bitcoin address, can the mining pools ...
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Why one miner can dig out many blocks continually in one moment?

I am new to bitcoin and blockchain, I browed the website just now. There is a question confusing me, I find that one miner dig out blocks many times even in one hour. For example, this miner dig out ...
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Don't miners control who is allowed to make transactions?

Simple question really, considering theres a very small group of miners controlling the chain ATM. Whats to stop them from being forced by the goverment to disallow certain transactions or just mining ...
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Is the 51% attack the only technical reason no country will adopt Bitcoin as a state currency? [closed]

Is the 51% attack the only technical reason no country will adopt Bitcoin as a state currency? Lets suppose a country with GDP size less than 300 Billion USD adopt the Bitcoin as an official currency. ...
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Robustness of bitcoin

I am wondering about the consequences of a potential 51% CPU attack on the bitcoin blockchain. Imagine that a state invests enough computational power to rewrite from scratch an entire blockchain, ...
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What are the chances bitcoin big mining pools to unite and do 51% attack?

Looking at this bitcoin hash rate distribution chart (https://www.blockchain.com/en/pools), it only takes 3-4 mining pools to unite and do a 51% attack. With this possibility, how can people still ...
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51% attack - apparently very easy? refering to CZ's "rollback btc chain" - How to make sure such corruptible scenario can never happen so easily?

I was shocked to see binance CZ comment to literally "roll back" the bitcoin chain by just "calling" in some favors from "friendly" Asian miners . This ONE person could effectively do it??? I mean ...
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If there are 20 nodes in network and all are receiving transaction and after 10 min

Question 1) If there are 20 nodes in network and all are receiving transaction and after 10 min all will pick transaction from their transaction pool and start creating block, now will all nodes will ...
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Is 10K full nodes enough to bitcoin to avoid 51% attack?

As I know bitcoin has about 10K full nodes. And the question is in my mind is that: This number is not huge! If someone has 6K servers, Can control the bitcoin via 51% attack? I was thinking if ...
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51% attack + ignore blocks not mined by yourself [duplicate]

If you own 51% of the mining power and decide to ignore all blocks not mined by yourself. You would eventually end up having the longest chain, and would eat up the 49% of block-reward you werent ...
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How to do a 51% attack on my own altcoin [closed]

recently I have been curious about 51% attacks so I created a fork of litecoin and want to do a 51% attack on the coin but don't know how to. please can you tell me how to do it. Thanks,
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How do I know that the majority of bitcoin miners are not XYZ government's facilities? [closed]

Even if "Satoshi Nakamoto" is/was actually a real person, how can I be sure that XYZ government (XYZ can be US, or China, or ...) does not have now (or will not have in the future) 51% of the hashing ...
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Do you really need more than 50% mining power in order to attack Bitcoin blockchain?

My question is about concept, so code is not related, however, do you really need 51% of the mining power in order to attack/replace the real bitcoin Blockchain? For example, a blockchain has a ...
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double spend attack: Is this actually true for the more time progress the higher the probability of success for attacker

I'm new here. I have a question here. Some experts keep saying that this assumption isn't formally correct and I don't really understand why or why they might be wrong. In the double spend attack; ...
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Is a 51% attack on bitcoin likely?

Given that the majority of bitcoin processing is done in China (source: https://bitcoinmagazine.com/articles/report-links-74-bitcoin-mining-china-sees-threat-network/), is it possible for a single ...
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Bitcoin is attacked by China miners by screwing with the network, what will Bitcoin do?

There was a report recently (https://arxiv.org/pdf/1810.02466.pdf) that stated that China controls 74% of the hashing power. They can choose to collude and attack the network by either doing a 51% ...
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