Article reprinted from: ChainFeeds
Author: LINDABELL
At the recent Devcon conference, Ethereum Foundation core member Justin Drake proposed the Beam Chain proposal, planning to upgrade the Ethereum consensus layer through zkSNARK and zkVM technologies to enhance the network's scalability, security, and efficiency. This vision has once again drawn attention to the importance of zkVM. As a general-purpose zero-knowledge virtual machine, zkVM can handle complex computations in a more flexible and efficient manner, while freeing itself from reliance on traditional smart contract logic.
Driven by this trend, projects like RISC Zero, Succinct, and Cysic are seen as important players in driving innovation in this field. Among them, RISC Zero has developed a series of open-source tools such as Zeth, Kailua, and Bonsai based on the RISC-V architecture zkVM, which not only enhances block verification and Rollup performance but also provides technical support for Ethereum's ZK upgrade.
RISC zkVM ecological product matrix: From core technology to scenario applications
RISC Zero is a zkVM implementation based on the RISC-V instruction set architecture, serving as a general-purpose zero-knowledge computing platform that supports multiple mainstream programming languages, such as Rust and C++, and can run nearly any computation task. Compared to other zero-knowledge technology platforms, RISC Zero's provers and verifiers are completely open-source, allowing developers to generate and verify proofs locally. In addition, RISC Zero's verifiers are compatible with multiple platforms, simplifying the development process of decentralized applications.
In June of this year, RISC Zero released zkVM 1.0. zkVM 1.0 not only supports multiple languages and complex computing tasks but also utilizes Continuations technology to break down large-scale computations into smaller segments, achieving efficient parallel computation and verification. According to the roadmap, RISC Zero plans to achieve a 20-fold improvement in zkVM performance and cost by the end of 2024, with optimizations including fully migrating the proof process to GPUs (80% completed), introducing new RISC-V v2 circuit designs, and specialized optimizations for recursive circuits. At the same time, RISC Zero is integrating a series of acceleration modules for algorithms like RSA, Keccak, and ECDSA to enhance the performance of Ethereum-related tasks and cryptographic operations.
Around the core capabilities of zkVM, RISC Zero has also developed a series of open-source tools and products. For example, through the Bonsai network, developers can generate zero-knowledge proofs without dedicated hardware; through the Steel tool, complex EVM computations can be transferred to off-chain environments for execution while maintaining verifiable results, reducing on-chain execution costs; and Blobstream Zero bridges Celestia's data availability layer, providing more possibilities for data sharing and verification in the modular blockchain ecosystem.
Zeth: Proving that the entire Ethereum block is correctly constructed
Zeth is an open-source Ethereum zero-knowledge block prover developed by RISC Zero based on its zkVM technology, which can verify the validity of Ethereum blocks through zero-knowledge proofs without relying on traditional validators or synchronization committees. RISC Zero defines Zeth as Type-0 zkEVM, which is fully compatible with the Ethereum protocol and improves developer efficiency through code reuse.
Ethereum co-founder Vitalik Buterin categorized zkEVM into four types in the article 'Different types of zk-EVMs', where Type-1 seeks complete and uncompromising equivalence to Ethereum; Type-2 aims for complete equivalence to EVM but not entirely to Ethereum; Type-3 is almost equivalent to EVM; and Type-4 is completely incompatible with Ethereum.
Thanks to the high performance of RISC Zero zkVM, Zeth can complete the verification of Ethereum blocks in a few minutes. Testing data shows that Zeth can generate block proofs at a speed of 1.1 MHz and extend GPU clusters through the 'continuations' feature, increasing the speed to 4.7 MHz to 6.3 MHz. This performance optimization also reduces the cost of proof generation. According to tests, the proof generation cost for a block containing 182 transactions is only $21.72, with a cost of about $0.11 per transaction.
At the same time, during the development of Zeth, the RISC Zero team made full use of components from the Rust ecosystem, such as revm, ethers, and alloy, enabling developers to quickly implement block proof functions and apply them to different scenarios. This design provides developers with more flexibility to adjust block construction logic as needed and adapt to future Ethereum improvement proposals.
At the application layer, Zeth provides efficient solutions for zk Rollup, light clients, and cross-chain bridges. The construction of traditional zk Rollup and zkEVM requires a significant amount of time and funds, which deters small teams. Zeth, based on a modular zkVM architecture, allows developers to easily customize block verification logic. For example:
zk Rollup: Zeth can quickly implement block proofs, shortening the development cycle and reducing the financial input for ZK Rollups.
Light clients: Verify block validity without rebuilding the block, reducing operational costs.
Cross-chain bridges: Zeth can verify the correctness of cross-chain data without leaking sensitive on-chain information through ZKP, reducing reliance on third-party trust and lowering the risk of cross-chain attacks.
In May this year, Zeth successfully expanded to support the extraction of Optimism block data from the Ethereum mainnet, generating ZKP to verify block correctness and also supporting on-chain verification. In other words, with the help of Zeth, Optimism can verify transactions more efficiently and resolve transaction disputes.
Bonsai: Allows developers to generate proofs without using their own hardware
Bonsai is a remote proof service designed specifically for zkVM applications, allowing developers to generate proofs without using their own hardware, thus resolving the contradiction between limited on-chain computing resources and high costs. With Bonsai, developers only need to define the zkVM application to be executed and the input data, and Bonsai can run the computation in the background and generate the corresponding zero-knowledge proof. This process does not require developers to deploy additional hardware. At the same time, Bonsai utilizes a large number of GPU clusters to support parallel processing of multiple computing tasks. Additionally, Bonsai provides a simple and easy-to-use API and SDK interface, allowing developers to easily integrate it into existing systems, further reducing development difficulty.
Based on this remote proof service, RISC Zero launched the open-source tool Bonsai Pay, which combines OAuth2.0 identity authentication and ZKP technology, enabling users to send or receive tokens on the Ethereum network via their Google accounts. For example, when Alice wants to transfer funds to Bob, she can use Bonsai Pay to input Bob's Google email and the transfer amount. Bob can then log into Bonsai Pay, enter the email address, and complete Google account authentication. Bonsai Pay will use OAuth 2.0 to generate an authorization token, proving that Bob is indeed the holder of that email address. Subsequently, Bonsai Pay calls the Bonsai proof service to generate a zero-knowledge proof, proving that Bob's Google account is associated with his wallet address. After the smart contract verifies the proof, it unlocks the funds and transfers them to Bob's wallet address.
Throughout the process, Bonsai Pay verified the fact that 'Bob's Google account is associated with his wallet address' using ZKP technology, while avoiding the disclosure of any specific information about the Google account.
Another important application of Bonsai is the Bonsai ZK co-processor (ZK Co-processor). It transfers complex computing tasks from on-chain to off-chain through zero-knowledge proof technology, generating tamper-proof proofs to ensure the correctness of results. Additionally, the deployment of the Bonsai co-processor is very simple; developers only need to write a zkVM application to handle the logic and call Bonsai through a simple Solidity contract to run computations and verify results. Throughout the process, the Bonsai proof service is responsible for generating zero-knowledge proofs for off-chain computations that can be verified on-chain.
The Bonsai ZK co-processor is suitable for on-chain applications that require high performance and low costs. For example, in DAO governance, it can transfer complex voting computations off-chain, significantly reducing on-chain gas fees. The Bonsai DAO Governor reduces gas costs per vote by over 50% through the co-processor, effectively improving governance efficiency and lowering participation thresholds.
Boundless: A verifiable computation layer
In traditional blockchain architecture, to ensure the validity of transactions, all nodes must re-execute all computations for each transaction. This 'global re-execution' model, while ensuring security and consistency, also incurs extremely high computing costs. To address this issue, RISC Zero launched Boundless, allowing a single node to complete computations and generate a verifiable zero-knowledge proof, enabling other nodes to confirm results by simply verifying that proof without re-executing computations.
Boundless simplifies the verification process through recursive composition technology. It merges multiple small zero-knowledge proofs into a single overall proof, allowing verifiers to check only one total proof instead of verifying all stage proofs one by one. To further optimize the efficiency of zero-knowledge proof generation, Boundless includes dedicated cryptographic acceleration circuits to enhance the efficiency of common tasks such as hash computation and digital signature verification.
Moreover, developers using Boundless do not need to have an in-depth understanding of zero-knowledge technology; they can simply write applications in familiar programming languages (like Rust or Solidity). Currently, Boundless is open for free access to developers. They can leverage the proving services provided by Boundless to quickly build and deploy zero-knowledge applications on any blockchain without migrating existing systems or updating verification contracts.
Blobstream Zero: A zkVM cross-chain bridge that simplifies cross-chain data verification
Blobstream Zero is a zkVM-based cross-chain bridge launched in collaboration between RISC Zero and Celestia, designed to seamlessly connect Celestia's data availability layer to the existing modular blockchain ecosystem. By sharing and verifying data on Celestia, Blobstream Zero enables more convenient data transfer and verification between chains.
As a completely open-source public product, Blobstream Zero allows any project or developer to run local instances and generate zero-knowledge proofs. In addition, Blobstream Zero can also provide support for ZK co-processors. ZK co-processors are essentially off-chain computing tools, so they require reliable data to perform computations. Blobstream Zero can obtain data from blockchains like Celestia and can generate ZK proofs to demonstrate that the transmitted data is reliable.
Steel: A new paradigm of smart contracts with off-chain execution and on-chain verification
Steel is an open-source tool launched by RISC Zero that utilizes zkVM technology to achieve off-chain verifiable smart contract execution. Through Steel, developers can transfer EVM operations from on-chain to off-chain execution while generating a zero-knowledge proof to ensure the authenticity and verifiability of the computation results.
Traditional smart contracts require complete execution of all logic on-chain, which not only incurs high gas costs but also limits the development of complex applications. Steel's off-chain computation and on-chain verification mechanism solves this problem. For example, in a simple smart contract, determining whether an account's ERC20 balance is greater than 1 and incrementing a counter variable. Traditional methods require fully executing logic on-chain, while Steel completes the computation off-chain and generates a zero-knowledge proof, requiring only on-chain verification of the proof without re-executing the contract logic.
Currently, RISC Zero has released Steel 1.0, and partners have successfully used this tool to develop applications. For example, in a contract call processing about 400,000 SLOAD operations, Steel shifts the computation to off-chain execution and then verifies the generated zero-knowledge proof on-chain. The cost of proof generation is less than $10, and the on-chain verification cost is below 300,000 gas.
Kailua: A hybrid ZK solution driving Rollup architecture innovation
Following the release of Zeth, RISC Zero launched Kailua, aimed at providing an upgraded solution for optimistic Rollups through a hybrid ZK Rollup approach. Traditional optimistic Rollups usually require a 7-day challenge period, leading to slow transaction finality, while ZK Rollups can achieve fast finality but incur high ongoing costs for generating zero-knowledge proofs. Kailua combines the advantages of both, achieving a balance between cost and efficiency. As an extension of the Optimism Kona framework, Kailua not only supports unmodified Kona running on zkVM but also introduces an innovative dispute resolution mechanism that reduces staking requirements and minimizes finality delays, thereby enhancing system efficiency and usability.
In Kailua's architecture, the dispute mechanism adopts a brand-new design. First, its dispute resolution mechanism removes time limits, allowing validators ample time to generate proofs when encountering network interruptions or other special conditions, thereby enhancing system resilience. Even in extreme cases, RISC Zero's zkVM's scalable architecture can complete proofs in under an hour. Additionally, Kailua's on-demand verification feature allows developers to flexibly configure verification frequency, enabling a gradual transition to a fully verified Rollup mode at lower costs.
Unlike ZK Rollup, Kailua's design does not require continuous proof generation. For low-frequency empty blocks or Rollups with special contract requirements, Kailua offers a more cost-effective option. At the same time, Kailua significantly reduces the staking cost requirements for Rollups. The staking amount for traditional optimistic Rollups increases linearly with longer finality periods, while Kailua's optimized design stabilizes staking requirements, allowing the system to maintain security and activity at lower costs even over long periods.
Currently, Kailua has been fully open-sourced. Developers can use its command-line tool to deploy a local Optimism test network and quickly upgrade to a network that supports ZK fault proofs. Kailua also supports simulating fault proposals to help developers understand how validators challenge erroneous states through zkVM, thereby gaining a deeper understanding of its dispute resolution mechanism. In the future, Kailua will further optimize costs and performance and expand support for more Rollup frameworks.
Conclusion
As seen from the above, RISC Zero's zkVM product matrix is driving the development of zero-knowledge proof technology in multiple fields. Zeth and Kailua focus on optimizing Rollup architecture, improving block verification efficiency and dispute resolution speed. Bonsai provides remote proof services, reducing hardware dependency and operational costs, allowing developers to build applications more efficiently. Blobstream Zero provides reliable support for the modular blockchain ecosystem by efficiently verifying cross-chain data. Additionally, Steel reduces the gas costs of smart contract execution through its off-chain computation and on-chain verification model.
Of course, while continuously improving the zkVM product matrix, RISC Zero is also pushing for innovations in the underlying zkVM technology. Recently, RISC Zero zkVM released version 1.2, introducing a new pre-compilation method that allows developers to deploy pre-compilation logic alongside applications without embedding it within the zkVM itself. This means developers can add new pre-compilation logic without modifying on-chain verification contracts or coordinating prover configurations, and without forking or making major changes to the zkVM for performance optimization. Moreover, by defining pre-compilation through applications, it can also reduce the computational cost of proof generation. For example, Automata integrated RSA pre-compilation, reducing execution cycles from 39 million to 217,000, with costs lowered by about 180 times.
With the continuous optimization of zkVM technology, its development potential will gradually be realized in multiple application scenarios. However, to better unleash this potential, it still relies on ecological collaboration and the practical performance of technology implementation.
