We are excited to share with you the first Spacemesh white paper! Shout outs to everybody who helped us get here. You know who you are out there!
Spacemesh is a work in progress as active research is underway. New versions of this paper will be published at https://spacemesh.io/whitepaper1/. Comments and suggestions may be submitted by contacting us at firstname.lastname@example.org.
This paper is written to specifically address technical readers who have an understanding of the capabilities and issues of existing blockchain protocols.
The audience may also be considered as participants; that is, readers who are interested in exploring approaches to solve these issues. Collaborating in this way will advance the state of blockchain infrastructure to make it more decentralized, useful, robust, scalable, and secure.
Thus far, all of the deployed blockchains exhibit centralization tendencies and scalability bottlenecks as they gain in popularity. Bitcoin and other Proof of Work (PoW) based systems contribute to massive energy consumption, whereas Proof of Stake (PoStake) based systems require trusted checkpoints and high collateral.
Enter SpacemeshOS: a blockmesh operating system powering an energy-efficient, decentralized, secure, and scalable smart contracts global computer and a cryptocurrency in the permissionless settings. The heart of Spacemesh is a new consensus protocol that replaces PoW with Proof of Space Time (PoST), and a chain with mesh topology.
The Spacemesh protocol allows newcomers to contribute to the security of the cryptocurrency network via unused storage space on their hard drives. PoST retains the properties of PoW that are useful for permissionless consensus, but with drastically lower energy emissions. In contrast to PoStake, the PoST mechanism enables users to participate in the system without large security deposits that are locked for long periods of time, and also avoids other nothing-at-stake problems, such as the higher risk of divergence due to hard fork replicas.
SpacemeshOS can support a highly scalable network with thousands of transactions per second, without compromising the decentralized nature of the system. This is achieved using an incentive-compatible protocol that is based on mesh topology - layered directed acyclic graph (DAG). As opposed to the simpler chain topology, the mesh avoids race conditions and guarantees that an honest miner will obtain a fair share of the rewards, regardless of the actions of other miners. Furthermore, the blockmesh enables far more frequent rewards than a blockchain, which means that pressures against decentralization are thwarted, since the individual miners have no need to rely on centralized mining pools.
Spacemesh is the first free open source, permissionless consensus protocol that neither relies on PoW nor PoStake, and is provably secure under the assumption that a majority of the participating storage is honest. The incentive-compatibility of Spacemesh increases the likelihood that this assumption will hold.