The technical architecture of B² Network is shown in Figure B² Network Architecture. Comprising two fundamental layers, Rollup Layer and Data Availability Layer, B² Network seeks to redefine the way we perceive Bitcoin Layer-2 solutions.
B² Network employs ZK-Rollup as Rollup Layer. ZK-Rollup Layer adopts the zkEVM solution, responsible for the execution of user transactions within the Layer-2 network and the output of related proofs.
Users' transactions are submitted and processed in the ZK-Rollup Layer. The users' state is also stored in the ZK-Rollup Layer. The batch proposals and the generated zero-knowledge proofs are forwarded to the Data Availability Layer for storage and verification.
Data Availability Layer includes Decentralized Storage, B² Nodes, and Bitcoin Network. This layer is responsible for permanently storing copies of rollup data, verifying rollup zk proofs, and ultimately performing the final confirmation on Bitcoin.
A pivotal aspect of B² Network, the decentralized storage serves as the repository for the ZK-Rollup's user transactions and their respective proofs. By decentralizing storage, the network inherently enhances security, reduces single points of failure, and ensures data immutability.
B² Nodes consist of multiple modules, performing various roles:
- They incentivize Decentralized Storage, ensuring accurate and efficient storage of B² rollup data copies through zk proof of storage and economic incentives.
- B² Nodes validate the zk proof of rollups, checking the accuracy and efficiency of zk rollup transactions and state generation.
- B² Nodes provide decentralized sequencer services for B² rollups, selecting sequencers in a DPoS-like manner, ensuring decentralization and preventing malfeasance by a single sequencer.
- B² Nodes supply Bitcoin block and transaction data for integrating Bitcoin state in B² rollups and generate zero-knowledge proofs to ensure data security.
- The Bitcoin committer module of B² Nodes writes
$B^{2}$ rollup data into Bitcoin via Tapscript, creates bit value commitments for zk proof verification, and performs final confirmations on Bitcoin through challenge-response mechanisms. - B² Nodes maintain Schnorr multi-signature verifiers.
Bitcoin Network is the final settlement layer for B² Network. Users can recover all B² rollup transactions through Bitcoin and validate their authenticity using zk proofs recorded on Bitcoin. B² Network employs zk proof verification commitment and challenge-response mechanisms for final confirmations on Bitcoin. This process, supported by Bitcoin's robust Proof of Work (POW) algorithm, ensures the security of B² rollup.
At last, the transaction flow is shown in Figure B² Transaction Flow