Subspace Network Integrates with OnFinality to Make Kusama More Decentralized
A TRUE 4th Generation Blockchain

Secure, Scalable, Decentralized

Subspace is the first protocol to fully resolve the blockchain trilemma
without making compromises.

Secure & Sustainable Consensus

Proof-of-Archival-Storage (PoAS)  consensus maintains the honest majority assumption and permissionless nature of Nakamoto consensus without the massive electricity cost of mining.

Fully
Decentralized

Decoupled execution keeps farming lightweight and resistant to pooling, while the farmer storage network allows the blockchain to "bloat" massively without becoming centralized.

Composite
Scaling

Block decoupling and data-availability sampling allow for vertical scaling, while our unique separation of consensus and computation provide for horizontal scaling at log(n) overhead to executors.

based on Years of original r&d

Subspace tech stack

Efficient
Nakamoto Consensus
Proof-of-Capacity text Proof-of-Capacity text Proof-of-Capacity text Proof-of-Capacity text Proof-of-Capacity text Proof-of-Capacity text
Randomness beacon text Randomness beacon text Randomness beacon text Randomness beacon text Randomness beacon text
Proof-of-Time text Proof-of-Time text Proof-of-Time textProof-of-Time textProof-of-Time textProof-of-Time textProof-of-Time textProof-of-Time textProof-of-Time textProof-of-Time text
Proofs-of-Capacity
Randomness Beacon
Proof-of-Time
Distributed
Archival Storage
Erasure Coding
Consistent Hashing
S/Kademlia DHT
Optimal
Vertical Scaling
Block Decoupling
Data Sampling
Super Light Client
Proofs-of-Archival Storage (PoAS)
Hourglass Schemes
Proofs-of-Replication
SLOTH 256-189
Decoupled Smart Contracts
Staked Execution
Stateless Farming
Fraud Proofs
Flat Horizontal Sharding
Virtual Beacon Chain
Global Farming
Local Execution

Nakamoto
Consensus

Distributed
Storage

Decoupled Computation

Composite
Scaling

Trustless Bridging

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built with the best technology

WebAssembly

Rust-Lang

Parity Substrate

LibP2P

THE BLOCKCHAIN TRILEMMA

The blockchain trilemma is a term coined by Vitalik Buterin to describe the challenges of creating a secure, scalable and decentralized blockchain. He argues that a blockchain can only achieve two out of the three features in practice.

Security means retaining safety and liveness for up to a one-half adversarial fraction of nodes (the honest majority assumption).

Decentralization means keeping the compute, storage, and network resources low enough for anyone to run a node on their laptop.

Scalability
means transaction throughput should increase as more users join the network and as their computer hardware improves.

Nakamoto
Consensus

Distributed
Storage

Decoupled Computation

Composite
Scaling

Trustless Bridging

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The consensus puzzle

The first problem is to find a secure consensus mechanism that is environmentally friendly, permissionless, and fair.

Proof-of-Work?

PoW or "one-CPU-one-vote" is simple, secure, and permissionless, but it comes at a high cost in electricity that is not environmentally sustainable and leads to centralized, or pooled, mining.

Proof-of-Stake?

PoS or "one-coin-one-vote" employs a system of virtual mining based on one's wealth. While eco-friendly, PoS is not fair or permissionless, instead encouraging a system whereby the rich only get richer.

Proof-of-Capacity?

PoC or "one-disk-one-vote" replaces mining with storage-intensive farming. In theory, PoC is secure, eco-friendly, and fair, but in practice, most designs devolve back to PoW or PoS models.

To solve this problem, we constructed Spartan, a simple and secure PoC consensus protocol that realizes the vision of free-and-fair consensus as described by "one-disk-one-vote".

Plotting Space

To begin, farmers write millions of tiny (4kb) pieces to their free disk space under an hourglass scheme. Each piece is encoded with a time-asymmetric permutation based on SLOTH. A tag is computed over each piece and stored within a Binary Search Tree (BST). Unlike Chia plotting does not require (or destroy SSDs) and is up to 10x faster. Unlike Filecoin, farmers do not have to stake coins proportional to their disk space. This allows anyone in the world to quickly and easily pledge their free space and participate in consensus.

Farming Blocks

Following Ouroboros, we construct a secure randomness beacon from the blockchain history itself. At each slot, all farmers search their BST for any tag close enough to the challenge to satisfy the difficulty setting. They may then compile the tag and corresponding encoding into a Proof-of-Replication (PoR) and produce the next block in the chain. Anyone may then cheaply verify the proof by inverting the encoding with the farmer's public key and checking the tag. This allows farming to be lightweight in terms of the storage and compute overhead required.

Maintaining Security

To prevent simulation attacks, the challenge is re-used over many consecutive timeslots. To prevent grinding attacks we segregate PoRs from the block content while basing the randomness solely on the PoRs. To prevent compression attacks we require farmers to periodically re-commit to their BSTs. To prevent long-range attacks, bribing attacks, and space-time trade-off attacks we employ a simple Proof-of-Time (PoT) based on AES-256. For a full analysis read our article on Securing Spartan.


Maintaining decentralization

The second problem is that PoC networks are prone to centralization, due to a mechanism design challenge we call the farmer's dilemma.

Farmer's Dilemma

Farmers may choose between using their storage to either a) retain the chain state and history or b) to maximize their plot size and return on investment.

Pooled Farming

As the chain grows, farmers will always choose the latter, at best becoming light clients, while at worst choosing to join a farming pool run by a trusted operator.

Centralization

If no one stores the history, nodes may only sync from centralized providers. If no one maintains the state, we must rely on trusted third-parties for our balance.

Subspace resolves the farmer's dilemma by incentivizing storage of the history and delegating state management to executor nodes.
allowing for the first truly decentralized PoC network.

PoAS Consensus

To incentivize farmers to retain the history we extend Spartan proof-of-space consensus into a proof-of-storage of the history of the blockchain itself. Under proof-of-archival-storage (PoAS) consensus, each farmer stores as many provably unique segments of the chain history as their disk space allows. The more pieces of the history a farmer stores, the more likely they are to be elected to produce a new block. To ensure farmers store as many unique pieces as possible we enforce a maximum plot size while discouraging sybil farming under multiple identities.

Distributed Archival Storage

Farmers store the history collectively, forming a distributed storage network which ensures the history is always available to download. To provide for proper load balancing and consistent replication, each farmer is incentivized to store pieces closest to its randomly assigned node id. To prevent the history from being lost, blocks are erasure coded into both source and parity pieces. To allow for efficient retrievals, farmers join a simplified Kademlia DHT. Importantly, this allows clients to embed data within a transaction, and later recover that portion of the history from the DHT, creating a scalable immutable object store.

Decoupled Smart Contracts

To relieve farmers of the burden of maintaining the state and preforming redundant computation, we apply the classic technique in distributed systems of decoupling consensus and computation. Farmers are solely responsible for ordering transactions, while a separate class of executor nodes maintain the state and compute the transitions for each new block. To ensure executors remain accountable for their actions, we employ a system of staked deposits, verifiable computation, and non-interactive fraud proofs.

No compromises scalability

The final challenge is to scale transaction throughput without sacrificing the security or decentralization of the network.

Bigger Blocks

One way to scale throughput is to increase the block size, but this leads to longer propagation times and a higher honest fork rate, reducing security.

Many Chains

Another technique is to scale-out with multiple chains or shards, but existing designs are insecure against an adaptive adversary who may target a single shard.

More Bloat

Both methods result in faster growth of the chain state and history, leading to blockchain bloat and centralization under a handful of powerful nodes.

While recent research shows how to scale securely, the bloat problem remains. Since Subspace already handles this challenge, to resolve the farmer's dilemma, it is indeed able to scale without compromise.

Secure Vertical Scaling

Subspace adapts the Prism scalability proposal to achieve high-throughput transaction processing without reducing security. When combined with data availability sampling and super light-clients, farming can remain low-bandwidth and decentralized.

Flat Horizontal Scaling

By employing a virtual beacon chain we eliminate the bottleneck of a single main chain and support up to 2^16 shards. Farmers rotate shards each block while executors may stake on as many different shards as they choose, following the Free2Shard design.

Permissionless Fast Finality

Subspace extends the Taiji fast confirmation protocol for PoC consensus, allowing farmers to achieve nearly deterministic finality within three blocks, reducing the confirmation latency of new transactions from minutes to seconds, without relying on executors.


A scalable platform fordecentralized applications

High Volume Transaction Throughput

The future is multi-chain and it's clear that users prefer AMMs over centralized exchanges. Subspace provides the layer one scalability needed to bridge numerous chains while allowing for trustless, low-latency, and high-throughput asset exchange.

Distributed Archival Storage

Since the history may grow far beyond the storage capacity of any single farmer, yet is still priced efficiently, Subspace is uniquely able to provide cheap, permanent dApp storage, while still making the data available to a global execution layer.

Scalable Smart Contracts

By decoupling execution and storage, then scaling each individually, Subspace allows for a much wider array of layer two constructions, limited only by the protocol designers imagination.