Sybil Attack is an online network security system threat in which an individual attempts to create multiple account identities.

Multiple Node or computer coordinates thereby control the network.

It's the same principle as creating multiple personal social media accounts - simple.

This has relevant implications in the cryptocurrency field. Just think about what would happen if someone intended to put multiple nodes on the blockchain network.

The term "Sybil" comes from the case of a woman named Sybil Dorsett who was diagnosed with "multiple personality disorder".

What problems will Sybil attacks cause?

If an attacker creates enough false identities (or Sybil identities), they can defeat the real nodes on the network with a majority vote.

They can then refuse to receive or transmit blocks in this case, effectively preventing other users from entering the network.

In the relatively large-scale Sybil attack, the premise is that when the attacker has controlled most of the computer network or hash rate, they can carry out a system attack covering 51%. In this case, they can easily change the order of transactions and prevent them from being confirmed. They can even take over and reverse transactions, causing double-spending issues.

For many years, computer scientists have devoted a lot of time to studying how to detect and prevent Sybil attacks. Each study has varying degrees of effectiveness, but there is still no guarantee of a perfect prevention solution.

So how does blockchain mitigate Sybil attacks?

Many blockchains use different "consensus algorithms" to help resist Sybil attacks, such as proof of work, proof of stake and

Proof of entrustment. These consensus algorithms are not actually effective against Sybil attacks, they just make it difficult for attackers to successfully execute them, making them impractical.

For example, the Bitcoin blockchain applies a specific set of rules for the generation of new blocks.

One of the rules is that if you want to have the ability to create blocks, your total mechanism processing power must be proportional to the ability to submit proof of work. This means that you must have the computer power required to create a new block, which is very costly and difficult for an attacker to do.

However, due to the intense intensity of Bitcoin mining and the motivation for high returns, miners are keen on legitimate mining methods

and will not attempt to Sybil attack.

In fact, in addition to Sybil attacks, there are other common types of attacks.

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