This is the 1248th issue of the original vernacular blockchain
Author | Produced by Yan Wenchun
｜Vernacular Blockchain (ID: hellobtc)
Friends who follow Bitcoin must have heard the term 51% hashrate attack. What does it mean, and what “bad things” can be done after launching this attack?
Today, I will briefly introduce things related to 51% computing power attacks.
01What
is a 51% attack?
In the Bitcoin white paper, it was stated that the sum of the control power of honest nodes is greater than the sum of the power of cooperative attackers, and the system is safe.
In other words, when the computing power controlled by malicious nodes in the system exceeds the computing power controlled by honest nodes, the system is at risk of being attacked.
This type of attack initiated by a malicious node controlling more than 50% of the computing power is called a 51% computing power attack.
Is it possible that all cryptocurrency systems are at risk of 51% computing power attack?
In fact, it is not. Only cryptocurrencies based on the PoW (Proof of Work ) consensus mechanism have 51% computing power attacks, such as Bitcoin, Bitcoin Cash, and Ethereum at the current stage.
02What
bad things can this attack do?
After understanding the 51% attack, you must be curious about what bad things this attack can do.
Double spending means that a "money" is spent twice or even many times. How does the 51% attack power double spend?
Suppose Xiao Hei has 666 BTC. He pays these Tokens and sends these Tokens to his other wallet address at the same time.
In other words, Xiao Hei's share of money was transferred to two people at the same time. In the end, the transaction sent to Dabai was confirmed first and packaged in a block with a block height of N.
At this time, Xiao Hei, who controlled more than 50% of the computing power, launched a 51% computing power attack. He reassembled the Nth block, packaged the transaction sent to him into the block, and continued to extend the block on this chain.
Due to the advantage of computing power, this amount will become the longest legal chain . In this way, the black 666 BTC double spent successfully, and the 666 BTC in the big white wallet "missed".
2. Suppress certain addresses to send/receive Bitcoin
In addition, what else can 51% hashrate attacks do? It can also suppress an address from sending/receiving bitcoins.
Xiao Hei and Da Bai have quarreled. Xiao He relies on his own control of 51% of the computing power. Knowing the Bitcoin address of Da Bai, he can keep Da Bai-related transactions unconfirmed.
For example, Dabai wanted to send 1 bitcoin to the "creation address" in order to pay his respect to Satoshi Nakamoto. Palm control more than half the force considered black, not packaged this transaction, not only black but also so do not let other miners packed this transaction.
How did Xiao Hei do it?
If the new block mined by other miners packs the transaction, Xiao Hei will choose not to continue mining after this block. He will choose to rebuild the new block after the previous block, and reject the transaction of Dabai. , Relying on his own computing power advantage, the chain that Xiao Hei forked will become the longest legal chain.
In this case, other miners have no choice but not to package transactions related to Dabai, otherwise the mined blocks will be isolated by Xiaohei, and the block rewards will be invalidated.
03
summary
With more than 50% of the computing power, you can do whatever you want, can you do any bad things? Actually it is not.
Even if you control more than 50% of the computing power, you cannot transfer other people's Tokens, because this operation requires a private key to sign. If you want to forge a signature to "steal coins", this behavior is not tolerated by honest miners. Will subvert the system consensus.
If you master more than 50% of a cryptocurrency's computing power, will you launch a 51% computing power attack? why? Come to the message area and talk about your views.
END
Previous post : Popular Science | The Evolution of Mining
"Disclaimer: This article is the author's independent point of view, and does not represent the vernacular blockchain position. This content is only for the popular science learning and exchanges of encryption enthusiasts, and does not constitute investment opinions or suggestions. Please take a rational view, establish a correct concept, and increase risk awareness. The copyright of the article and the final interpretation right belong to the vernacular blockchain. 』
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