CKB (Nervos Common Knowledge Base)¶

Nervos CKB (Common Knowledge Base) is an open, Layer 1 public blockchain designed to serve as an "extension engine" for the Bitcoin ecosystem, providing a Turing-complete smart contract platform while inheriting as much of Bitcoin's security as possible. CKB is not merely a Bitcoin Layer 2, but rather an independent blockchain with a unique Cell model and PoW consensus mechanism, whose design philosophy is deeply inspired by Bitcoin's UTXO model.

Problems Addressed¶

Bitcoin excels at providing decentralization and security, but the limitations of its scripting language make it difficult to support complex smart contracts and high-performance decentralized applications. CKB aims to solve:

Bitcoin's programmability limitations: Bringing Turing-complete smart contract capabilities to the Bitcoin ecosystem without modifying Bitcoin's core protocol.
Asset universality and security: Providing a platform where any type of asset (not just BTC) can be issued, managed, and used with high security and decentralization.
Developer flexibility: Supporting multiple programming languages and virtual machines to lower the barrier to smart contract development.
Future-proof architecture: Building a sufficiently flexible underlying architecture that can adapt to future technological developments (such as ZKP, sidechains, etc.).

Implementation Mechanisms and Principles¶

CKB's core innovations lie in its Cell model and the design philosophy of a Common Knowledge Base.

Cell Model¶

CKB's Cell model is a generalization of Bitcoin's UTXO model. * Generalized UTXO: While Bitcoin's UTXOs store unspent bitcoin amounts, CKB's Cells can store arbitrary types of data, including tokens, smart contract code, state data, and more. Each Cell has a "lock script" (ownership script) and an optional "type script." * Ownership and Type: The lock script defines who can unlock and spend the Cell (similar to Bitcoin's P2PKH), while the type script defines the Cell's behavior and state (similar to a smart contract). * State Isolation: Each Cell's state is isolated. Cell inputs and outputs are updated through transactions, making concurrent processing and state management efficient.

Universal Verification Layer and Virtual Machine¶

CKB is designed as a Universal Verification Layer (Common Knowledge Base). This means it does not force users to use a specific programming language or virtual machine. Instead, through a highly abstracted RISC-V architecture CKB-VM, it supports the execution of machine code compiled from multiple high-level languages (such as Rust, Go, JS).

PoW Consensus and Economic Model¶

Proof of Work: CKB employs a PoW consensus mechanism similar to Bitcoin's, ensuring a high degree of decentralization and censorship resistance.
Token Economics: CKB's native token is CKBytes (CKB). CKBytes are used not only for paying transaction fees but, more importantly, they represent state storage space on the CKB chain. Holding 1000 CKB means you can store 1000 bytes of data on CKB. This design tightly couples the "land" ownership on the blockchain with token value, incentivizing users to efficiently utilize on-chain space.

Homomorphic Binding with Bitcoin¶

Through mechanisms such as the RGB++ protocol, CKB can achieve homomorphic binding with Bitcoin UTXOs. This means that Bitcoin UTXOs can establish a strong association with CKB Cells, enabling Bitcoin native assets to undergo complex smart contract operations on CKB while inheriting Bitcoin's security.

Key Features¶

Extreme flexibility: The Cell model and universal CKB-VM enable CKB to support virtually any type of asset and smart contract, including extensions for Bitcoin native assets.
Robust security: Through PoW consensus and the potential for homomorphic binding with Bitcoin, CKB aims to provide security guarantees similar to Bitcoin's.
Layered architecture: CKB focuses on being a Layer 1 security and data availability layer, while higher-level Layer 2 solutions or DApps can be built on top of it.
UTXO philosophy: Inherits and generalizes the advantages of Bitcoin's UTXO model, such as state isolation and determinism.
State rent mechanism: CKB token holders own storage space, incentivizing users to clean up abandoned state and maintain network efficiency.