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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 operators.

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 Dilithium, 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 thousands of small (1MiB) pieces to their free disk space grouped into sectors of 1GiB. Each piece is masked with a memory bandwidth bound based on a custom implementation of Chia Proof-of-Space. Unlike Chia, plotting does not fill the SSD with random data, but creates unique partial replicas of history for each farmer. Unlike Filecoin, farmers do not have to stake coins proportional to their disk space. This allows anyone in the world to quicklyandeasily pledge their free space and participate in consensus.

Farming Blocks

Following c-Nakamoto PoS, we construct a secure randomness beacon from the blockchain history itself. At each slot, all farmers partially scan their plots for any 32B chunk close enough to the challenge to satisfy the difficulty setting. They may then compile the chunk, commitments proving it to be a part of chain history and corresponding proof-of-space into a Proof-of-Replication (PoR) and produce the next block in the chain. Anyone may then cheaply verify the proof by performing 64 hashes and 2 KZG verifications. This allows farming to be constant and lightweight in terms of the storage and computing overhead required.

Maintaining Security

To prevent simulation attacks, the entropy from the blockchain history is re-used over many consecutive time slots. 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 submit the whole encoding to produce a block and make decompression equally infeasible in a slot time as plotting. To prevent long-range attacks, bribing attacks, and space-time trade-off attacks, we employ a simple Proof-of-Time (PoT) based on AES-128. For a formal security analysis read our research paper.

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 operators nodes.
allowing for the first truly decentralized PoC network.

PoAS Consensus

To incentivize farmers to retain the history we extend 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 rule on which pieces each farmer can store tied to their identities. A change of identity would require re-plotting, protecting from Sybil attacks.

Distributed Archival Storage

Farmers store the history collectively, forming a distributed storage network (DSN) that ensures the history is always available to download.
To prevent the history from being lost, blocks are erasure-coded into both source and parity pieces.
To provide for proper load balancing and consistent replication, each farmer stores unencoded pieces closest to its ID in a hot cache taking below 1% of pledged storage.
To allow for efficient retrievals, a node first requests pieces from the farmers’ hot caches. Only in a rare case of a cache miss farmers are asked to decode the pieces from their plot cold storage. The properties of the archiving protocol and the DSN we built a unique chain sync mechanism based on pulling pieces and reconstructing the chain locally. This allows Subspace nodes to store only recent blocks and purge archived history, keeping memory requirements for full nodes constant no matter how long the chain grows.

Decoupled Smart Contracts

To relieve farmers of the burden of maintaining the state and performing 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 operator nodes maintain the state and compute the transitions for each new block. To ensure operator 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 operators 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 operators.


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.

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