IPFS and Filecoin mining have always attracted much attention. The editor has compiled some knowledge about Filecoin mining to provide a reference for miners who want to learn more and maximize their mining profits.

01 PoPep Principle

PoPep, or Proof of Replication, is a new type of storage proof scheme that allows storage miners to convince users/other miners that data has been copied to their mining machines. This scheme can effectively prevent storage cheating problems such as witch attacks, outsourcing attacks, and generation attacks.

The simplified steps of proof of replication are as follows: First, the miner creates a specific copy R. When the miner stores a sector (this sector is a logical sector defined by the filecoin network), the data of the sector is added to the miner's secret key pair for a slow sequential encoding to form a specific storage copy of the miner, making each data copy different. The result of sealing is a data copy with a Merkle tree structure.

Second, the miner generates proof Πpos of the stored data copy. After the miner stores the data and completes the seal, how can he prove to a filecoin network without a centralized server that the miner has indeed stored this copy?

The idea of ​​zero-knowledge proof is used in the process of generating the proof. "Zero-knowledge proof is a bit complicated, and interested readers can read relevant materials." That is, the verifier believes that the miner does store a copy of the data without having to own any data. How is this done?

Based on the random challenge C proposed by other verification nodes in the network, for example, if the miner wants to challenge position 8, the miner needs to calculate the path from leaf node D8 to root node Root, output a proof Πpos, and return it to the verification node that initiated the challenge.

Third, the verification node verifies the proof of the storage miner. After the verification node obtains the proof of the storage miner, it can verify it through the given information. When the verification result is equal to 1, it means that the miner has indeed stored a specific copy. The verification process is very fast. The specific verification algorithm needs to be explained in detail after the code is released. The white paper is relatively rough.

02 Sector

A sector (sector in the white paper) refers to a storage space specific to a storage miner, which is used to measure effective storage and the unit space for submitting storage proofs. When a storage miner has stored all the data in a sector (it may not be full but it can be sealed, but some storage space will be wasted), the sector sealing will be run, and after sealing, the replication proof will be submitted to form effective storage.

Currently, Protocol Labs has two possible solutions for sectors. One is a fixed size, such as 1G; the second is a size specified by miners, such as 1G or 10G.

So what is the use of the size of the unit sector? According to the description of the filecoin blockchain data structure in the white paper, the sector ID will be stored in the allocation table of the blockchain, and one sector will consume about 300 bytes of on-chain storage space.

It can be calculated that, assuming the sector size is 1GB, after a period of time, the effective storage of the entire network reaches 10EB, then the storage space required by the sector on the blockchain is approximately 3TB, which does not include the blockchain space occupied by orders and transactions, that is, maintaining a filecoin full node requires more than 3TB of storage space.

If the sector is too small, it will take up a lot of block space. However, if the sector is too large, it will not be easy to seal, which will cause some effective storage to be wasted. I believe that Protocol Labs will make a very good decision on how to balance the sector size and blockchain space.

03 Proof of Space and Time

Time proof can be understood as continuous replication proof, that is, miners must continuously generate proofs and submit storage proofs within a submission cycle. If the proofs are not submitted continuously and in a timely manner within the submission cycle, some tokens will be deducted.

The process of generating a proof is very similar to that of replicating a proof, except that the input of the space-time proof is the previously generated proof as an input parameter. This ensures the continuity of proof generation, which is explained in detail in the white paper.

04 Proof of Spacetime and Consensus Mechanism

The consensus mechanism of blockchain is one of the core elements of blockchain projects. Filecoin's consensus mechanism reaches consensus based on proof of time and space. This consensus mechanism is as simple and clear as POW.

For example: ① Suppose there are two miners A and B in the whole network. Miner A seals 2 sectors full of data at a certain moment and keeps submitting time-space proofs; Miner B seals 4 sectors full of data at this moment and keeps submitting time-space proofs; ② At this time, the effective storage of the whole network is 6 sectors; ③ The probability of miner A being elected as the leader node is 2/6; ④ The probability of miner B being elected as the leader node is 4/6; ⑤ That is, the probability of a miner being elected as the leader node at a certain moment = the capacity of the sealed sectors / the total capacity of the sealed sectors of the whole network

05 Miners, Miner Actors and Mining Machines

According to the demo released by the filecoin team, filecoin mining is divided into miners and miner actors. What is the relationship between them?

① Miner: It can be understood as an address and key pair similar to BTC and ETH. It is needed when issuing orders and completing orders. The mining income also belongs to the miner's address.

② Miner actor: Each miner can have multiple miner actors. When issuing orders, the miner actor is used as the unit. Each miner actor also has an address, and the storage of multiple miner actors of the miner can be accumulated.

③ Mining machine: Each miner actor corresponds to a physical mining machine.