1. What is CKB?
CKB is the underlying L1 blockchain of the Nervos Network, operating similarly to Bitcoin and using a proof-of-work (PoW) consensus mechanism. It employs an upgraded version of Bitcoin's algorithm, NC-MAX, to enhance network efficiency and response speed by accelerating transaction confirmation times and reducing orphan block rates. Bitcoin targets a ten-minute block interval, adjusting mining difficulty approximately every two weeks. In contrast, CKB dynamically adjusts the block interval based on network activity changes (approximately every four hours), optimizing its performance.
2. What are the advantages of CKB?
Security
CKB uses the Eaglesong function to ensure the security of the network, which is an ASIC neutral custom hash function that can replace the widely used SHA256 hash function. Eaglesong is a sponge function optimized for several cryptographic elements, providing the same level of security as other proof-of-work (PoW) hash functions, specifically tailored for the Nervos Network.
The convenience of payment channels
As an underlying public chain, CKB can be scaled through payment channels, such as the payment channel framework Perun developed by Polycrypt. By processing transactions off-chain and settling on-chain, these payment channels can support a variety of applications from micropayments to payment gateways, enhancing the performance of CKB. Perun leverages CKB's Cell model, where Cells carry capacity, Lock Script, Type Script, and data to manage the state of the channel. One implementation of the channel (PerunLockScript) can manage access to the channel's real-time Cells, while another implementation (PerunTypeScript) can handle the validation logic for state transitions. The transitions from funding the channel to closing it are all managed automatically. As of the time of publication, Perun is still in testing and has not yet been launched on the CKB mainnet. The core developers of Nervos are also working to connect CKB to Bitcoin's Lightning Network, enabling users to exchange BTC and CKB without relying on third parties.
3. What is the Cell model?
The Cell model is the core data structure of CKB that can store and verify any data on-chain. The original scripting language of Bitcoin and the UTXO model limit its ability to perform the complex calculations required for executing smart contracts. In contrast, CKB generalizes the UTXO model, allowing for more flexible data storage and verification. Unlike Bitcoin, which uses a single script to validate transactions, CKB introduces a dual-script in its Cell model:
Lock Script ensures that only authorized users can access and use the contents within a Cell, similar to Bitcoin.
Type Script is an optional script used to set rules on how to use or modify the Cell in future transactions.
Compared to the limited options in Bitcoin, this system enables CKB to support more functionality, making it more suitable for various applications. Each Cell in CKB is a programmable Cell that can store different data types, such as tokens, smart contracts, and specific application states. It can also run complex scripts similar to those in Turing-complete languages. Cells operate independently, meaning they can be updated or referenced without affecting other parts of the blockchain, enhancing scalability through parallelism.
4. What is CKB-VM?
CKB-VM is the execution engine of CKB, used for running smart contracts and decentralized applications. This virtual machine uses the RISC-V instruction set, which is a flexible, simple open-source hardware architecture set (ISA) that supports various programming languages, including popular languages like C and Rust. This broad compatibility differentiates CKB-VM from other blockchain virtual machines that are usually limited to specific languages, opening it up to a wider developer community. The CKB network also supports SDKs for mainstream languages such as JavaScript, Rust, Go, and Java, facilitating developers to use familiar tools for development. This makes it easier for developers to create complex decentralized applications using familiar programming languages.
Moreover, the architecture of CKB-VM provides predictable gas fees, secure execution, and efficient integration with the Cell model, which helps effectively manage state and validate transactions. The predictable gas fee model avoids unexpected costs, enhances user experience, and simplifies contract development.
5. CKB's Token Economics
The native token of the Nervos Network, CKByte (CKB), plays a crucial role in maintaining network security and incentivizing effective storage. The main roles of CKB in the network include:
Granting data storage rights to token holders.
As transaction fees for on-chain transactions.
As block rewards distributed to miners to ensure network security.
In addition, the sources of CKB tokens are threefold: (1) Genesis block; (2) Base issuance; (3) Secondary issuance.
Genesis Block
At the mainnet launch in November 2019, a total of 33.6 billion CKB tokens were minted in the genesis block, of which 8.4 billion CKB tokens (25% of the initial issuance) were immediately burned. Of these burned 8.4 billion CKB, 5.04 billion tokens were used for on-chain storage ('occupying on-chain space'), while the remaining 3.36 billion tokens were in liquid state ('liquidity'). The corresponding state allocation of these burned tokens was aimed at ensuring that miners could initially obtain at least 15% of the secondary issuance, while the treasury fund could obtain at least 10%. Notably, all CKB tokens allocated to the treasury fund have been burned, and this setting can only be changed through a hard fork of the network.
The distribution of CKB in the genesis block is as follows:
Public offering (~21.50%): The largest portion of the genesis block was allocated to public investors in 2018 and was fully released at the mainnet launch in November 2019.
Ecosystem fund (17.00%): The ecosystem fund will support third-party developers within the Nervos ecosystem. In the genesis block plan, 3% of this allocation was already in place at the mainnet launch, with the remaining portion to be distributed over two years, concluding by December 2022.
Team (15%): Reserved for the project team, with a four-year lock-up period ending in May 2022.
Private placement (14%): Offered to private investors in July 2018. Of this, 66.60% was released at the mainnet launch, with the remaining portion released at the end of a two-year lock-up period in 2020.
Partners (5%): This allocation is reserved to help establish strategic partners for the Nervos Network, with a four-year lock-up period.
Testnet rewards (0.5%): These rewards were fully distributed to participants in the testnet and bug bounty programs at the mainnet launch.
Burning (25%): This portion was directly burned in the genesis block to ensure that miners and the treasury fund continue to receive secondary issuance.