My TL;DR: A high throughput blockmesh (different than blockchain tech, but similar in nature) with some smart contracts capabilities, using Proof of Space Time consensus mechanism.
Various projects compete to put out the fastest blockchain out there, by coming up with variations of consensus protocols, parallelism and other mechanisms that help achieve transaction finality in as little time as possible. But it’s obviously not easy to solve the trilemma that Vitalik put forward: Scalability, Decentralization, Security – choose two.
Spacemesh takes a swing at it by using the Proof of Space Time consensus mechanism, with an Elapsed Time twist. Proof of Space is as secure as Proof of Work, but differs from it because it requires to allocate disk storage to solve an incoming challenge from the network, instead of CPU/GPU and a lot of electricity. Proof of Space on its own is however susceptible to some attacks, so mixing it with a Proof of Time – proving that the space has been reserved for a certain amount of time – makes it more secure. Bram Cohen from Chia (a similar project that uses PoST) explains it best in his Stanford lecture.
In brief, it makes it so that someone joining the network with a lot of more storage than everyone else will not be able to hijack the network, as they also need to wait the real amount of time it took the network to get to its current state, while the network itself progresses onwards. By comparison, it takes 51% of available hash power on PoW networks to assume control, as Bitcoin Gold learned the hard way.
Spacemesh improves on PoST by adding a concept of Elapsed Time, which represents the time passed since the initial challenge was learned. Smarter people than me can explain this better. Suffice to say, this is a simplification of the PoST consensus mechanism, as it reduces some of the overhead involved, thus making it more efficient.
Instead of using blockchain technology, where transactions are stored in a block, which is mined via Proof of Work, Spacemesh uses a blockmesh. It’s a layered DAG where each node is an indexed block, and edges only point backwards, thus making it a linear chain-like structure. Using this technology has a few neat advantages. The main one, in my opinion, is that it enables Spacemesh to reward all participants directly, proportional to their staked storage. For example, a user that has 10% of storage in the Spacemesh network will constantly get 10% of the rewards for blocks it helps mine, instead of having a 10% chance to get the next reward. This is great for decentralization, as single PC users running a Smartmesh node will get instant payouts without the need to join a paid pool or otherwise be extremely lucky.
Governance of Spacemesh will be done via the Spacemesh foundation, which will appoint or revoke 3rd party maintainers of various code repositories, in yearly cycles. Anyone can become a maintainer, but the foundation reserves the right to replace them at any time. Protocol decisions will be still taken by the foundation, with some of them being brought up to a community vote.
What I like:
- First PoST project with Smart Contracts
- Encourages decentralization and low energy use
- Very strong technical team
What I dislike:
- Smart contracts are mentioned as a capability, but no other details such as which language will be used
- There will be no ICO, they raised $3mn in seed funding and no news of them looking to raise more (probably all private)
Overall, I like Spacemesh a lot. It brings a novel implementation of PoST, similar to what Chia wants to do, but with smart contracts capabilities. I dislike the fact that there will be no ICO, as this is tech I would invest in if I could. But I love the fact that they only needed $3mn to start work on what can turn out to be very impressive technology, with a coin that can be mined by everyone with a PC. This is an extremely important difference to how Bitcoin & Ethereum ended up today – massive farms that eat up a lot of power, and much closer to the ideal vision of decentralization. I will make sure to start mining it as soon as it comes out.