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What exactly is a Sybil Attack?
Sybil Attacks is one of the three network attacks that Filecoin faces. It means that malicious nodes deceive the network by cloning IDs to obtain additional benefits. This method is called Sybil Attacks. So, where did the term witch attack come from?
Based on Flora Rhea Schreiberie's 1973 novel The Witch, the film of the same name is the story of a woman in psychotherapy who goes by the pseudonym Sybil Dorsett. She was diagnosed with Dissociative Identity Disorder, a combination of 16 personalities. If there is a malicious node in the network, the same malicious node can have multiple identities, just like the 16 identities split by the heroine in the movie. Node, such as the malicious node disguised as multiple identities, this is Sybil attack.
Popular understanding: users submit network requests and store N independent backups. At this time, if a malicious node generates Y identities, the network thinks it is Y independent storage nodes, and the actual storage score of the malicious node is less than N shares or only one, but the malicious node may obtain N shares Independent backup (reward), in other words, it may have obtained N times the block explosion reward. At this time, the malicious node attack is successful.
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So how does Filecoin solve the Sybil attack?
Filecoin's Solution to Preventing Sybil Attacks
First of all, friends, you need to understand why filecoin needs to prevent witch attacks?
It's very simple. For example, a manufacturer only has 1 node for Filecoin mining, and then through a Sybil attack, 10 nodes mine Filecoin at the same time, but the manufacturer only contributes the storage computing power of 1 node, as if they only do I got a job but falsely claimed 10 rewards. This situation deceived the Filecoin official and the Filecoin network. So, in order to prevent fraud and fairness, the Sybil attack problem must be solved.
Proof of replication is Filecoin's solution to prevent Sybil attacks. The core idea of proof of replication is to ensure that the prover keeps independent backups. So, how is proof of replication implemented?
In the first step, the encryption time is long and the decryption time is short. The extension of the encryption time prevents malicious miners from temporarily generating encrypted files to challenge in time, because to generate copy proofs, the prover must be required to use encrypted files as input, that is to say, only when the miners actually store the encrypted files can they To ensure that the challenge is completed on time, the purpose of shortening the decryption time is to extract files faster and reduce the consumption of computing resources.
The entire process above is Filecoin's Proof of Replication (PoRep).
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Filecoin's Proof of Replication Implementation Process
The basic definition of PoRep is this: the verifier V provides a unique piece of data proof π to the prover P to convince P to store a specific backup Di of the data D itself, and this proof is the answer to the challenge C generated for P.
The popular understanding is this: a miner Liu (Verifier V) said to a user Xiao Zhang (Xiao Zhang released multiple storage tasks to the network), "I have a unique data certificate in my hand, which was released by you. There is only one copy of a backup in the storage task”, as long as the two “password proofs” match, and as long as the user Xiao Zhang confirms that there is no problem, then the miner Liu can get the task bonus corresponding to the backup (Filecoin Network challenge to burst out coins).
Can Filecoin be 100% perfect against Sybil attacks?
No, at the beginning of the year, the Filecoin network was still unstable, and there were even system bugs during the testnet period. Some node miners maliciously obtained a lot of virtual FIL coins. So, do you guys understand why the Filecoin network needs to be tested? It is to ensure the stability of the system after the official mainnet goes online. Otherwise, if there are problems or loopholes after the mainnet goes online, it will not only be unfair to other miners, but may have a serious impact on the entire Filecoin network ecology.
