As the Bitcoin ecosystem continues to attract funding, various technical approaches related to Bitcoin have emerged. L2, staking, and DeFi projects that bring BTC into Ethereum or Solana have all taken the stage, and BTC’s native DA project has also begun to receive market attention.
Nubit is an extensible Bitcoin native DA layer that is secured by Bitcoin. Nubit effectively expands the data capacity of Bitcoin, providing support for applications such as Ordinals, L2, and oracles, thereby expanding the scope and efficiency of the Bitcoin ecosystem. It aims to fully inherit the security of Bitcoin, including economic security, tamper resistance, and censorship resistance.
During the hot cryptocurrency market, Bitcoin transfers or transactions often incur high fees and congestion. The increased demand in the market last year led to the storage of over 14GB of data on Bitcoin, resulting in high costs. According to information from its official website, Nubit can reduce transaction fees by over 95% and increase data throughput by over 100 times.
Nubit primarily consists of four basic components: validators, trustless bridges, full storage nodes, and light clients. Validators use the Practical Byzantine Fault Tolerance (PBFT) consensus algorithm and are responsible for proposing, validating, and ensuring the integrity of transactions. The minimal trust bridge acts as an intermediary, charging users storage fees and distributing rewards to validators through payment channels. Full storage nodes receive block data from validators and are responsible for reliable data storage. Light clients retrieve blocks broadcasted by validators, including data commitments, and may randomly request verification from full storage nodes to validate the DA.
In terms of consensus mechanism, Nubit still adheres to the semi-synchronous network assumption. It introduces a consensus algorithm called NuBFT, which is a variant of the BFT consensus algorithm and combines the slotting process of data partitioning based on Reed-Solomon encoding with KZG’s generation. Even if some data nodes are corrupted, the original data can be recovered using Reed-Solomon encoding.
Furthermore, the KZG submitted to Bitcoin ensures the validity of the original data. By integrating the block partitioning of RS encoding and the generation of KZG into the consensus algorithm, the integrity, availability, and scalability of stored data are directly linked to the consensus process, significantly enhancing the robustness of the entire DA system.
It is worth noting that Nubit uses BTC as the primary token for the consensus protocol, inheriting the economic security of Bitcoin through Bitcoin-native staking mechanisms like Babylon. In contrast, general-purpose DA layers like Celestia use their own network tokens, introducing additional trust assumptions outside of Bitcoin.
In terms of data availability, Nubit adopts a hybrid approach to address potential network disruptions caused by node data encoding errors. Nubit integrates full nodes and light nodes to ensure data integrity. Firstly, Nubit uses KZG as a proof of validity to ensure DA, reducing memory, bandwidth, and storage requirements while maintaining simplicity. Even in the event of a complete collapse of the Nubit network, nodes can still recover data using full nodes and KZG commitments submitted to Bitcoin. To further enhance network scalability, Nubit incorporates lightweight nodes equipped with Data Availability Sampling (DAS). This addition allows for larger block sizes to meet the growing demand for data availability.
However, unlike other Bitcoin L2 solutions, Nubit does not have a smart contract execution layer.
In terms of trustless cross-chain bridges, previous Bitcoin L2 solutions often relied on centralized bridges, which could potentially introduce security vulnerabilities due to the specific architecture of Bitcoin. Nubit, on the other hand, directly chooses the Lightning Network, allowing Nubit to establish a secure and trustless bridge within the Bitcoin ecosystem.
Nubit settles network fees using Bitcoin payment channels, which is a key distinction from other BTC bridge solutions. Nubit users do not need to meet the requirement of pre-deposits. Instead, they directly handle transaction fees within the state channels of each transaction, ensuring the security of user funds directly related to Bitcoin itself. Additionally, Nubit’s design allows for emergency withdrawals, allowing users to recover funds by closing Bitcoin payment channels even if Nubit ceases operation.
In the past, BTC technical practices, to some extent, such as SegWit and Taproot, have enhanced Bitcoin’s DA. However, Nubit’s emergence seems timely as the modularization and L2 trends were not yet prominent, and now a new solution has emerged. After collaborating with projects like Babylon, Merlin, and BounceBit, Nubit is preparing for the official launch of its mainnet later this year. The future development is worth paying attention to.