LumiBit's ZK-EVM
Overview
LumiBit introduces an innovative Bitcoin Layer 2 solution, leveraging ZK-EVM to offer enhanced scalability, privacy, and decentralization. It features a universal circuit design for seamless Ethereum smart contract migration, efficient transaction verification using Halo2 and rollup optimizations to reduce costs using ZKG commitment scheme. The solution addresses current Layer 2 challenges with a Type 2 ZK-EVM, providing an ecosystem akin to Ethereum. Future developments focus on implementing a Type 1 ZK-EVM for complete ecosystem migration and strategies to lower transaction fees, including succinct ZK proofs and specialized client solutions.
Scroll Based ZK-EVM
The Ethereum Virtual Machine (EVM) stands as the cornerstone of the Ethereum ecosystem. It’s not just an industry standard but also symbolizes extensive compatibility, a mature ecosystem, a vast developer community, and abundant development resources. The EVM-based ecosystem’s security and robustness have been proven over the years, enabling developers to write complex smart contracts flexibly and programmably, catering to a variety of application needs.
To fully implement the Ethereum ecosystem on Bitcoin Layer 2, EVM equivalence is essential. Hence, LumiBit has opted for Type 2 EVM, which ensures 100% EVM equivalence, choosing ZK-rollup for this equivalence solution.
Circuit Design
As mentioned earlier, LumiBit has implemented a Type 2 ZK-EVM based on Scroll’s circuit design. In zero-knowledge proofs, circuits are crucial for generating and validating proofs, representing programs in a specific format. For instance, proving hash(x) = y requires rewriting the hash function in circuit form, which only supports basic expressions like addition and multiplication. This makes programming in circuit language challenging, requiring the reconstruction of complex logic, including conditional and looping structures, from these basic operations.
The universal circuit in ZK-EVM is thus tailored for executing smart contracts to ensure EVM equivalence. It involves constructing a universal EVM circuit to verify all EVM opcode steps. The universal circuit supports Turing-complete computations and fast contract deployment. Based on Scroll, Lumibit use recursive proofs to simplify verification processes and reduce computational load. To further decrease computational overhead, we have introduced several optimizations including using gas-saving Poseidon Hash, and integrating Halo2 and polynomial commitments for optimized computations.
Developers work with LumiBit’s ZK-EVM without directly engaging with the underlying general circuit. This circuit acts in the background to facilitate ZK proof for contract deployment and interaction.
Final Thoughts
In our journey to enhance Bitcoin’s Layer 2 capabilities, LumiBit’s innovative approach with ZK-EVM and polynomial commitments marks a significant stride towards scalability and efficiency. Our commitment to a future-proof ecosystem, focused on seamless integration and reduced transaction costs, sets the stage for broader adoption and technological advancements in the blockchain sphere. As we continue to explore and innovate, the potential for a more interconnected and efficient blockchain network becomes increasingly tangible.
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