The Nervos CKB
(Common Knowledge Base)

Nervos CKB is a Layer 1, Proof of Work and Store of Value blockchain - a permissionless, decentralized, immutable and secure base layer that provides store of assets and common knowledge for the network. In a blockchain context, "common knowledge" refers to current data or "state" verified by global consensus.

The CKB acts as the foundation for decentralized trust of a layered and decentralized economy, enabling and ensuring the security of the trustless activities of the upper layers and the whole ecosystem.

Nervos CKB is the only PoW multi-asset & store of value general purpose blockchain for the new crypto-economy.

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A Sustainable Multi-asset, Store of Value Blockchain

Designed to best support on-chain verification and off-chain computation - the Common Knowledge Base (CKB) is an open source, permissionless and Proof of Work secured blockchain that serves as a decentralized custodian of 'common knowledge'. Designed to provide sustainable security and be a preservation focused, store of asset and store of value blockchain - this allows the CKB to serve as the trust anchor for the entire Nervos Network.
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Like Bitcoin, it is maximally secure, permissionless and censorship-resistant

Unlike other "decentralized computation platforms" that rely on novel consensus protocols or questionable decentralization assumptions to increase throughput (TPS), CKB adopts and improves upon Bitcoin's battle tested Nakamoto consensus - NC-Max - that ensures the anti-fragile and attack resistant properties that only a Proof of Work system can provide.

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A layer 1, specifically built for layer 2 scaling solutions

The Nervos CKB is purposefully built for layer 2 development, scaling solutions and enables layer 2 protocols (side chains, state channels, payment channels and more).
By leveraging the security of the layer 1 CKB, it provides unlimited scalability and allow tradeoffs for application-specific concerns such as privacy and finality for the Nervos Network ecosystem.

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Native token aligns the interests of all network users

The CKByte’s unique crypto-economic design make it an ideal use case for Store of Value as well as capturing the total value of the network to increase security and aligning the interests of Users, Miners, Developers and Node operators. It includes a crypto-economic design not just to facilitate transactions, but also for long-term value preservation which scales with network growth and value creation.
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Built for developers and native smart contract capabilities

Built for Developers and Layer 2 solutions, The CKB allows developers to program with a range of mainstream programming languages. With a low level virtual machine, libraries and crypto-primitives (such as signature algorithms or key functions) can be built and directly deployed on the virtual machine (VM) with no hard forks needed while taking advantage of the security and low level VM for value storage and transaction verification on the CKB.
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Solves the biggest challenges facing blockchains like Bitcoin and Ethereum today.

Features such as decoupling of computation and verification for flexibility and scalability, alignment of SoV and MoE users to incentivize security, sustainable blockchain data growth and consensus optimization to combat selfish mining are just a few of the issues solved via the Nervos Common Knowledge Base protocol, crypto-economic and Virtual Machine design.

Our Testnet is LIVE! Please see here on how to run a node and participate in the network

Crypto-Economics

The CKB economic model focuses on state (remembered information). The native tokens, CKBytes represent rights to occupy state storage. For example holding 1000 CK Bytes would allow a user to create a cell with 1000 bytes in capacity or multiple cells that add up to 1000 bytes in capacity.

Owners can utilize their CKBytes to store state or lend their capacity to others. An implicit cost proportional to disk space and time is created - if an owner utilizes their cell capacity to store state, they will incur an opportunity cost of their potential earnings from lending out the capacity. They will also forgo secondary issuance rewards from the NervosDAO. This is the CKB's solution to the long-standing state bloat problem.

CKB is a "Store of Assets" platform. Miners earn CKBytes, which are required to store assets. As demand for assets on CKB rises, the demand for storage space on the blockchain rises as well, and the miners' block rewards is expected to become worth more. This translates crypto-asset demand into miner revenue and will increases platform security as assets on the platform increase in price.

The protocol constrains state growth through monetary policy, collecting state rent through a "targeted inflation" scheme from state users. When base issuance stops, miners will still receive income from state rent (secondary issuance).

Learn more from the Nervos CKB Token Economics RFC.

Programming Model

CKB provides a turing-complete programming model - the cell model. Like smart contract platforms, CKB is versatile and stateful, though it is a state verification and storage system (like Bitcoin) rather than a computation platform. This means CKB transactions include both inputs and outputs like Bitcoin and never produces unexpected results.

While the CKB verifies and stores states, computation-intensive state generation happens on Layer 2. Cells are immutable and store arbitrary data, which could express anything from token ownership to executable code.

Each cell has associated scripts to express cell ownership and/or verification logic. Each node will execute these scripts and verify that outputs match the proofs provided in the transaction. With this architecture, users can confirm new states before broadcasting state transitions, nodes can identify transaction dependencies and verification can be parallelized where possible.

Learn more about the cell model.

Consensus

CKB consensus is based on Proof of Work and the Nakamoto consensus. It's designed for openness, censorship resistance and high performance in distributed environments with network delay and Byzantine node faults.

CKB's PoW algorithm (NC-Max) adjusts block difficulty in response to network conditions, increasing throughput when the network of nodes is well-connected and slowing it when the block orphan rate passes a certain threshold.

In open, permissionless blockchain networks, censorship resistance comes from the broadest consensus scope. With a low barrier for full node participation, CKB is intended to be run by a robust network of affordable full nodes with no barrier to joining such as appoval, application or 'staking' requirement thus insuring decentralization. Participants of the decentralized network can verify history and state independently without trust in a third party or service.
This creates a neutral platform free of censorship or confiscation risks, the fundamental reasons why public blockchains like Bitcoin are valuable.

Click here to learn more.

Storage & Transactions

In the Nervos layered architecture, the CKB stores state and defines valid state transitions, while Layer 2 (the generation layer or computation layer) processes most transactions and generates new states.

Layer 2 participants only submit states to the CKB when broader agreement and global consensus is necessary. If all corresponding on-chain verification passes, new states are securely stored as common knowledge on the nodes in the peer-to-peer network.

The Nervos Network is designed so that state and computation are separated, providing each layer greater flexibility and scalability. Owning and moving assets on CKB carries a higher cost and provides the highest degree of security, which is best suited for high value assets and long term asset preservation.

Layer 2 can scale transaction throughput and state storage by leveraging the CKB for asset security and/or safety through additional verification protocols, similar to the Lightning Network or Plasma.

Virtual Machine

Though blockchains can be created with the ease of software, upgrading them involves challenges similar to those found in hardware systems. To deal with these challenges, the CKB Virtual Machine (CKB-VM) utilizes RISC-V, an implementation standard designed for chips, which provides a stable, frozen core instruction set.

The CKB-VM is a RISC-V standard compliant implementation, existing cryptographic libraries written in C or other common languages can be easily ported to CKB-VM and used.

CKB implements cryptographic primitives as ordinary assembly running on the VM - no cryptographic primitives are hardcoded. CKB is crypto-agnostic and can evolve. New cryptography can be deployed and used just like an ordinary library.

Innovations such as Schnorr or BLS signatures, zkSNARKs/zkSTARKs and post-quantum cryptography can be implemented without affecting other users or requiring social consensus/hard forks. Updating key algorithms is as simple as storing the algorithm implementation in a new cell and pointing existing references to the new cell.

One last benefit of RISC-V: by measuring execution time on physical hardware, resource utilization can be approximated and inform accurate VM resource pricing (gas) and overhead assumptions.

Check out the CKB VM paper for more details.

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The Multi-asset, Store of Value Blockchain

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