Understanding Spacemesh

The Proof of Space and Time (PoST) protocol is a unique consensus mechanism used by Spacemesh. It’s designed to be more energy-efficient and accessible than traditional consensus mechanisms like Proof of Work (PoW) or Proof of Stake (PoS).

For a more basic overview of what Spacemesh is, check out my article on the basics. To help you understand the terminology, check out my article on terms and processes.

Proof of Space refers to a method where a participant in the network, known as a “smesher”, demonstrates that they have allocated a certain amount of storage space to the network. In Spacemesh, this is done by generating and storing data on the smesher’s hard drive. This process is known as “Smeshing”.

Proof of Time, on the other hand, is used to ensure that a certain amount of time has passed between different steps of the protocol. This is achieved by using a sequential computation that takes a certain amount of real-time to compute, but is quick to verify. This prevents participants from pretending that they have stored the data for longer than they actually have.

The combination of Proof of Space and Proof of Time in the PoST protocol allows Spacemesh to achieve a high level of security and fairness, while also being energy-efficient. It enables anyone with a computer to participate in the network by contributing disk space, without the need for ongoing energy-intensive computations. This makes Spacemesh more accessible and inclusive than many other blockchain networks.

Spacemesh operates on a unique time structure that involves POET rounds and epochs. An epoch in Spacemesh is a fixed period of time during which certain events and tasks are scheduled to occur. Each epoch in Spacemesh is 14 days long.

A POET (Proof of Elapsed Time) round is a period that starts in the middle of an epoch and runs until the middle of the next epoch. This means that each POET round spans across two epochs. The POET protocol provides a simple way to assert the passage of time between two events in a trustless and verifiable manner, which is crucial for the operation of the Spacemesh protocol.

Between each POET round, there is a 12-hour window known as the “cycle gap”. During this cycle gap, all nodes in the Spacemesh network are required to submit proofs that are generated from their allocated storage space. These proofs are part of the Proof of Space and Time (PoST) consensus mechanism used by Spacemesh, and they help to secure the network and determine which nodes are eligible to create blocks in the Spacemesh blockchain.

This structure of epochs, POET rounds, and cycle gaps allows Spacemesh to maintain a secure, decentralized, and fair protocol where all participants have an equal opportunity to contribute to the network and earn rewards. In order to make this more comprehensible, I have created a public calendar here that shows the first year of spacemesh epochs, poet rounds, and cycle gaps.

This unique structure is depicted well in this image which I have sourced from the Spacemesh blog post titled Genesis Timeline. That article also explains how the initial ‘golden ATX’ was developed using a specific bitcoin block. You can read more about it here: https://spacemesh.io/blog/genesis-timeline/.