Introduction

Bitcoin introduced the world to the first-ever consensus mechanism in 2009. This launched the beginning of a new era, however, its excess energy consumption posed a problem, spurring developers to look for more viable solutions to the mechanisms’ shortcomings like the Proof of Stake (PoS), the Delegated Proof of Stake (DPoS) consensus mechanism, and a newer solutions called theProof of Space-Time consensus mechanism, which combines the best of the Proof of Space and Proof of Time consensus mechanisms.

What is Proof of Space (PoSpace)?

Proof-of-Space is an evidence-based consensus mechanism that requires the participant to prove he has reserved the prescribed amount of storage space and that the space is filled with data specified by the network. It can be carried out through a hash function to map the data to a short output known as “Commitment.”

Once mapped, the participant sends the short output to the network as proof of their reserved storage space. Once the network receives the proof, it can ask the participant for a portion of the data linked to their commitment. The participant will provide this commitment within a certain period to prove their honesty or activeness.

What is Proof-of-Time (PoT)?

Proof-of-Time (PoT) is a decentralized consensus algorithm that selects validators according to their ranking scores and fixed stakes. A ranking score is the number given to each validator by the network’s algorithm to show how accurately the validator has validated previous data. It also comprises feedback from other validators about their interactions with the validator.

A fixed stake, however, is a staking method that mandates every validator to stake the same amount of the platform’s native token to join the consensus process. While similar, it varies from the Proof-of-Stake (PoS) mechanism that allows validators to stake large amounts of platform tokens to participate in the consensus process.

With the Proof-of-Time (PoT) consensus, any node can become a validator if it stakes the required number of tokens and has a good ranking score. This is possible through a Verifiable Delay Function (VDF) that randomly selects block proposers, known as time electors, and block confirmers, known as time nodes.

Lastly, while all nodes have equal token stakes, the Verifiable Delay Function (VDF) prioritizes nodes with higher ranking scores to propose or confirm blocks.

What is Proof-of-Space-Time (PoST)?

The Proof-of-Space-Time (PoST) consensus mechanism is a novel concept that combines both the Proof-of-Space (PoSpace) and the Proof-of-time (PoT) to create a consensus algorithm that allows network participants to prove they have reserved a specific amount of storage space for a specified period of time, while barely using computational and electrical power.

It was developed to create eco-friendly and scalable decentralized networks by using storage space as a resource. This greatly opposes the Proof-of-Work (PoW) consensus, which relies on solving cryptographic puzzles that consume tons of electricity and computing power.

Lastly, the Proof-of-Space-Time (PoST) can adjust the proof difficulty by changing the time duration of the storage instead of raising the computational requirements, boosting the security of the network without having to consume more energy. By focusing on storage, Proof-of-Space-Time (PoST) reduces network operations costs, reduces environmental adverse effects, and creates a more decentralized network.

How Does Proof-of-Space-Time (PoST) Work?

To participate in the PoST network, a node must first create a large dataset on the disk, known as a “Plot.” The created Plot comprises cryptographic proofs built on public parameters known as challenges. The network updates the challenges regularly to ensure the plots stay active and are not just created and abandoned.

Once the node is created, the next step is the creation of new blocks in the network. To do this, the node has to submit proof showing that it has stored the plot for a specific period of time, known as an epoch. This proof is a part of the plot created earlier that matches the network’s current challenge.

Once the proof is provided, the network verifies it by ensuring it matches the challenge brought up and previous proofs submitted by the same node. By doing that, the network ensures that nodes do not alter or delete their plots during each epoch.

Lastly, the node that can provide proof the fastest and most accurately is granted the right to produce the next block and earn rewards.

Benefits of Proof-of-Space-Time (PoST)

The combination of storage and time grants the Proof-of-Space-Time consensus several advantages that are highly beneficial to the networks that make use of the consensus and users of the network themselves. Some of these benefits include:

Cost Efficiency

While it is believed that the cost greatly depends on the capacity, in actuality, it is linked to the duration of storage used. By needing proof that the reserved space isn’t tampered with for a certain period, the PoST ensures regular use of the storage, drastically cutting the cost.

Energy Efficiency

Unlike the proof of work consensus, which consumes a ton of energy while mining, the Proof of Space-Time consensus consumes significantly less energy. It relies more on disk space and proof than computational power and mining.

Decentralization

The Proof-of-Space-Time consensus can stay truly decentralized, unlike the Proof-of-Stake consensus. This is possible due to the mechanisms allowing users to participate in providing storage space rather than stake large amounts of the network’s token, such as with the Proof-of-Stake mechanism.

With the PoST system, storage is a resource and is used in place of financial investments. This ensures that each participant can actively take part in the network, as no particular group or participant can dominate the operations of the network.

Security

The Proof-of-Space-Time consensus has a dual system security that ensures only nodes meeting the Space and Time requirements can participate in the network. This limits foul play by potentially bad nodes and cuts down possible attacks against the network.

Blockchains Making Use of Proof of Space-Time Consensus Algorithm

Although still a novel concept, a handful of projects have adopted the Proof of Space-Time Consensus Mechanism. Some of these projects include:

The Chia Network

Source: Chia

The Chia network is a De-Fi payment system created to reduce transaction cost and improve the efficiency of network transactions. The protocol uses its own smart contract programming language called Chialisp, which is auditable, secure, and transparent. It also helps create new cryptographic tools to raise the security of its smart contract.

Rather than use a mechanism that relies on tokens or mining, the Chia network relies on computer storage hardware through the Proof of Space-Time consensus mechanism. Network farmers are rewarded with the Chia token by dedicating a portion of their hard drive to store random data called plots.

Once created, the network generates a challenge obtained from previous blocks and sent to farmers to locate on their reserved storage (plots). When the challenge is found and the network has been alerted, it is provided to a participant called “Timelord” who then performs the calculations obtained from the data provided by the farmer.

With the Proof of Space-Time consensus, it can offer services like Atomic Swaps, Recoverable Wallets, Authorized Pays, Rate-Limited Wallets, Clawback Escrow, and Slow Paper Wallet.

Filecoin

Source: Supra

Filecoin is a blockchain-based network designed for decentralized data storage. The platform allows users to operate Lotus nodes through their computers. These nodes provide decentralized storage functions for the network and allow users to mine Filecoin tokens through the Proof of Space-Time Consensus method.

On Filecoin, the Proof of Space-Time consensus is used to prove that storage providers are continuously providing the storage as they claim. Deals are made between clients and storage providers for the storage providers to provide storage for a specified period between 180 to 540 days.

During the specified periods, storage providers must continuously prove that the data in their possession is available and immutable. The platform has a proving period where every storage sector of 32 or 64 gigs is verified once every 24 hours.

Each proving period is broken down into 48 30-minute deadlines that stay separate from each other. Storage space is then grouped into partitions, which are always verified within the same proving deadline

Proof-of-Space-Time (PoST) vs. Other Consensus Mechanism

By building on the existing Proof of Space (PoSpace) consensus and blending it with the Proof of Time (PoT) consensus, Proof-of-Space-Time (PoST) enhances the safety and effectiveness of networks. This grants the consensus certain advantages over other consensus mechanisms such as the Proof-of-Work (PoW), Proof-of-Stake (PoS), and Proof-of-Capacity.

Proof-of-Work (PoW) Vs Proof-of-Space-Time (PoST)

Proof-of-work is the consensus mechanism used by Bitcoin. It validates and adds new blocks by having miners solve difficult mathematical equations. While known for its security, it is also notorious for its high energy consumption and need for advanced computational hardware.

Proof-of-Space-Time (PoST), however, is a mechanism that boasts of its environmental friendliness and low energy consumption. Rather than focus on advanced computing like Proof-of-work (PoW), the Proof-of-Space-Time (PoST) relies on participant storage allocation for a specified duration.

With these features, the Proof-of-Space-Time (PoST) can conserve more energy and allows parallel block creation and verification, boosting scalability. Lastly, unlike PoW, which is first come, first served and only available to miners with advanced hardware, PoST is fair and allows all nodes to create blocks without their level of resources or influence.

Proof-of-Space-Time (PoST) Vs Proof-of-Stake (PoS)

Proof-of-Space-Time (PoST) and Proof-of-Stake (PoS) consensus mechanisms boast reduced energy consumption rates but vary in block creation and validation. The PoS consensus focuses on the amount of coin the user holds and stakes into the network, while the PoST is designed to reward participants for storing data on the blockchain.

While both mechanisms are environment-friendly, the Proof-of-Stake consensus can become centralized and lose its permissionless system. This is because the platform is totally reliant on its token, allowing users with more tokens to have more say in the network’s decision-making process. However, with Proof-of-Space-Time, participants stake storage space they already own to participate in validating and creating blocks.

Proof-of-Space-Time (PoST) Vs Proof-of-Capacity

The Proof-of-Capacity and the Proof-of-Space-Time share similar attributes, with both mechanisms depending on the use of storage space in validating blocks. However, unlike PoST, the Proof-of-Capacity consensus allows nodes on the network to use empty spaces on their hard drive to mine the network’s token. It allows users to store a list of possible solutions on their device’s hard drive before the mining process begins.

This allows users with more storage space to save more possible solutions, giving them better chances to match the required hash value, leading to more chances to mine and earn rewards.

Conclusion

The Proof-of-Space-Time consensus ushers in a new era of blockchain consensus mechanisms that provide security and efficient use of scarce resources. Its combination of Space and Time provides enhanced decentralization, boosting greater adoption of the mechanism.