What is Proof of Spacetime?
Proof of Spacetime (PoSpaceTime) is a consensus mechanism that ensures a network participant (e.g., data miners) continuously stores a piece of information for an agreed time period.
The consensus mechanism requires the prover to generate cryptographic proofs periodically to ensure the stored information remains intact for an agreed-upon period of time.
Then, they record these proofs on the blockchain, allowing the user who stored the data to verify that their data is securely stored.
Filecoin’s use of Proof of Spacetime
Filecoin is a crypto project offering its users decentralized storage services. It uses Proof of Spacetime to ensure that storage miners (network participants that provide storage space for rewards) continuously store data.
This is how it works:
Miners store the data and prove it with a Proof of Replication, a proof system that validates that the miners have created and stored a unique copy of the data. Then, they periodically generate Proof of Spacetime proofs (timestamped with the time the proof is generated) to confirm the ongoing storage of the data in time.
Recording these proofs on the blockchain allows the user to verify that their data is stored properly.
PoSpaceTime is a variant of proof of storage which allows a verifier to verify that a prover has stored its data for some period.
A. Shahaab, B. Lidgey, C. Hewage, and I. Khan
Proof of Stake vs. Proof of Spacetime vs. Proof of Capacity
People often confuse Proof of Spacetime with Proof of Stake (PoS) or Proof of Capacity (PoC). While all consensus mechanisms are used in blockchain networks, they are different. Let’s see their main characteristics.
Proof of Stake
- Relies on users staking crypto to validate transactions and create new blocks.
- New blocks are created by validators with the most crypto staked.
- The more crypto a user stakes, the more influence they have over the network.
Proof of Spacetime
- Encourages users to dedicate spare storage space for network rewards.
- Utilizes the user’s storage space to reach consensus and validate transactions.
- Validators prove ownership of storage by storing cryptographic data on a portion of their storage disk.
Proof of Capacity
- Miners store pre-computed data on a portion of their hard drives.
- Miners will get higher or lower rewards depending on the amount of storage space dedicated.
Summary
To sum up, Proof of Spacetime is a consensus mechanism demonstrating that a storage provider has stored a piece of data from the beginning to the end of the agreed-upon period.
HAHAAB, A., LIDGEY, B., HEWAGE, C., & KHAN, I. (2019). Applicability and Appropriateness of Distributed Ledgers Consensus Protocols in Public and Private Sectors: A Systematic Review. Cardiff School of Technologies, Cardiff Metropolitan University.
https://core.ac.uk/download/pdf/224739954.pdf
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