Proof-of-Spacetime

Proof-of-spacetime is a blockchain consensus mechanism that allows network participants to prove that they have provided the network with some storage space for a certain amount of time.

What Does Proof-of-Spacetime Mean?

Proof-of-Spacetime (PoSt) is a consensus algorithm that allows validators (typically storage miners) to prove they’ve allocated a specific amount of storage space for a continuous period. This mechanism ensures network security by verifying that participants are consistently maintaining their storage commitments rather than only providing space intermittently.

The system works by timestamping blocks added to the blockchain. For a block to be accepted in a PoSt-based network, it must contain accurate timestamps that demonstrate the storage miner has been continuously storing unique network data over time.

Proof-of-Spacetime is a combination of two consensus mechanisms – proof-of-space (PoSpace) and proof-of-time (PoT).

• Proof-of-space – PoSpace is an algorithm that enables a network participant to demonstrate their capacity to allocate a significant amount of memory or storage space to confirm transactions and generate new blocks. In short, they prove that they can store network data.
• Proof-of-time – PoT is a consensus mechanism that selects validators based on their ranking scores (the number showing the accuracy of the validator’s previously validated data) and fixed stake. It prioritizes the node’s performance and how long the node has been active in the network to gauge its reliability.

Filecoin is a popular example of a network using the PoSt consensus mechanism.

How Does PoSt Work?

Network participants typically demonstrate their ability to allocate significant storage space by creating a large dataset known as a plot. This plot contains proofs based on public parameters called “challenges,” which are regularly updated to ensure the plot is always active. 

After this, the participants have to prove that they have been storing the plot over a certain timeframe (known as an epoch) for the right to add a new block to the blockchain. The network then confirms if the proof, which is often a segment of the plot, matches the current challenge and previously submitted proofs by the individual. This ensures that the participant doesn’t delete or modify their plots with each epoch.

After vetting miners’ plot storage, the network then grants the right to create the next block and receive the attached block rewards to the first participant to provide the most accurate proof.