Written by: LINDABELL
At the recent Devcon conference, Ethereum co-founder Justin Drake proposed the Beam Chain proposal, planning to upgrade Ethereum's consensus layer through zkSNARK and zkVM technology to enhance the network's scalability, security, and efficiency. This vision also renewed attention on 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 the constraints of traditional smart contract logic.
Driven by this trend, projects like RISC Zero, Succinct, and Cysic are seen as important participants in driving innovation in this field. Among them, RISC Zero, with its zkVM based on the RISC-V architecture, has developed a series of open-source tools like Zeth, Kailua, and Bonsai, which not only enhance block validation and Rollup performance but also provide technical support for Ethereum's ZK upgrade.
RISC zkVM Eco Product Matrix: From Core Technology to Application Scenarios
RISC Zero is a zkVM implementation based on the RISC-V instruction set architecture. As a general-purpose zero-knowledge computing platform, it supports multiple mainstream programming languages such as Rust and C++, and can run virtually any computational 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. Additionally, RISC Zero's verifiers are compatible with various platforms, adapting to different blockchain ecosystems and simplifying the development process of decentralized applications.
In June this year, RISC Zero released zkVM 1.0. zkVM 1.0 supports multiple languages and complex computational tasks, utilizing Continuations technology to split large-scale computations into smaller segments for 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. Optimizations include completely migrating the proof process to GPUs (80% completed), introducing new RISC-V v2 circuit designs, and special optimizations for recursive circuits. Meanwhile, RISC Zero is integrating a series of acceleration modules for algorithms such as RSA, Keccak, and ECDSA to enhance performance for 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 run in an off-chain environment while maintaining result verifiability and reducing on-chain execution costs; and Blobstream Zero bridges the Celestia data availability layer, offering more possibilities for data sharing and verification in the modular blockchain ecosystem.
Zeth: Proving that the entire Ethereum block is constructed correctly
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 sync committees. RISC Zero defines Zeth as a Type-0 zkEVM, fully compatible with the Ethereum protocol while enhancing development efficiency through code reuse.
Ethereum co-founder Vitalik Buterin categorized zkEVM into four types in his article 'Different types of zk-EVMs', where Type-1 strives to achieve complete and uncompromised equivalence to Ethereum; Type-2 aims for complete equivalence to EVM but not to Ethereum; Type-3 is nearly equivalent to EVM; and Type-4 is completely incompatible with Ethereum.
Thanks to the high performance of RISC Zero zkVM, Zeth can validate Ethereum blocks within minutes. Test data shows that Zeth can generate block proofs at a speed of 1.1 MHz and can extend GPU clusters through the 'continuations' feature, boosting the speed to between 4.7 MHz and 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 per-transaction cost of about $0.11.
At the same time, during the development of Zeth, the RISC Zero team fully utilized components from the Rust ecosystem, such as revm, ethers, and alloy, enabling developers to quickly implement block proof functionalities and apply them to different scenarios. This design provides more flexibility to developers, allowing them to adjust block construction logic as needed and adapt to future Ethereum improvement proposals.
At the application level, 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 capital, deterring small teams. Zeth, based on a modular zkVM architecture, allows developers to easily customize block validation logic. For example:
zk Rollup: Zeth can quickly realize block proofs, reducing the development cycle and capital investment for ZK Rollup.
Light clients: Verify block validity without rebuilding blocks, reducing operational costs.
Cross-chain bridge: Zeth can verify the correctness of cross-chain data through ZKP without leaking sensitive on-chain information, reducing reliance on third-party trust and mitigating the risk of cross-chain attacks.
In May this year, Zeth successfully expanded to support extracting Optimism block data from the Ethereum mainnet and generating ZKP to verify block correctness, also supporting on-chain verification. In other words, with 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 specifically designed for zkVM applications, allowing developers to generate proofs without using their own hardware, thus addressing the conflict between limited on-chain computing resources and high costs. Through Bonsai, developers only need to define the zkVM application they wish to execute and the input data, and Bonsai can run the computation in the background and generate the corresponding zero-knowledge proof. This process requires no additional hardware deployment by developers. Additionally, Bonsai utilizes a large number of GPU clusters to support parallel processing of multiple computation tasks. Furthermore, Bonsai provides a simple and easy-to-use API and SDK interface, allowing developers to seamlessly 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 OAuth 2.0 authentication and ZKP technology, allowing users to send or receive tokens on the Ethereum network using their Google accounts. For example, when Alice wants to transfer funds to Bob, she can enter Bob's Google email and the transfer amount through Bonsai Pay. Bob can then log into Bonsai Pay, enter his 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. Afterwards, 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. Once the smart contract verifies the proof, it will unlock the funds and transfer 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' through 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 computational tasks from on-chain to off-chain through zero-knowledge proof technology, generating immutable proofs to ensure the correctness of the results. Additionally, deploying the Bonsai co-processor is very straightforward; developers only need to write a zkVM application to handle 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, which can be verified on-chain.
The Bonsai ZK co-processor is suitable for on-chain applications requiring high performance and low cost. For example, in DAO governance, it can transfer complex voting calculations off-chain, significantly reducing on-chain gas costs. The Bonsai DAO Governor reduces the gas cost per vote by over 50% through the co-processor, effectively improving governance efficiency and lowering participation barriers.
Boundless: A verifiable computing layer
In traditional blockchain architecture, to ensure the validity of transactions, all nodes need to repeatedly execute all computations for each transaction. This 'global re-execution' model, while ensuring security and consistency, also incurs extremely high computation costs. To address this issue, RISC Zero launched Boundless, allowing a single node to generate a verifiable zero-knowledge proof after completing computations, with other nodes only needing to verify the proof to confirm the results without re-executing the computations.
Boundless simplifies the verification process through recursive composition technology. It combines multiple small zero-knowledge proofs into a single overall proof, allowing verifiers to check one total proof instead of validating all stage proofs individually. To further optimize the efficiency of zero-knowledge proof generation, Boundless incorporates dedicated cryptographic acceleration circuits, optimizing common tasks such as hash calculations and digital signature verifications.
Furthermore, developers using Boundless do not need to have in-depth knowledge of zero-knowledge technology; they can simply write applications in familiar programming languages (such as Rust or Solidity). Currently, Boundless is open for free access to developers. Developers can leverage the proving services provided by Boundless to quickly build and deploy zero-knowledge applications on any blockchain without having to migrate existing systems or update verification contracts.
Blobstream Zero: A cross-chain bridge for zkVM that simplifies cross-chain data validation
Blobstream Zero is a cross-chain bridge based on zkVM launched by RISC Zero in collaboration with Celestia, aimed at seamlessly connecting Celestia's data availability layer to existing modular blockchain ecosystems. By sharing and verifying data on Celestia, Blobstream Zero facilitates more convenient data transmission and verification between chains.
As a fully open-source public product, Blobstream Zero allows any project or developer to run a local instance and generate zero-knowledge proofs. Additionally, Blobstream Zero can provide support for ZK co-processors. ZK co-processors are essentially off-chain computation tools, so they require reliable data to perform calculations. Blobstream Zero can obtain data from blockchains like Celestia and can prove the reliability of the transmitted data by generating ZK proofs.
Steel: A new paradigm of smart contracts for off-chain execution and on-chain verification
Steel is an open-source tool launched by RISC Zero, utilizing zkVM technology to achieve off-chain verifiable smart contract execution. Through Steel, developers can transfer EVM operations from on-chain execution to off-chain while generating zero-knowledge proofs to ensure the authenticity and verifiability of the computation results.
Traditional smart contracts require complete on-chain execution of all logic, leading to high gas costs and limiting the development of complex applications. Steel's off-chain computation and on-chain verification mechanism addresses this issue. For example, in a simple smart contract, determining whether an account's ERC20 balance exceeds 1 and incrementing a counter variable. The traditional method requires full on-chain execution of logic, while Steel performs the computation off-chain and generates a zero-knowledge proof, with only verification on-chain, eliminating the need to re-execute contract logic.
Currently, RISC Zero has released Steel 1.0, and partners have utilized this tool to develop applications. For example, in a contract call processing about 400,000 SLOAD operations, computation was transferred to off-chain execution through Steel, and the generated zero-knowledge proof was verified on-chain. The proof generation cost was less than $10, and the on-chain verification cost was below 300,000 gas.
Kailua: A hybrid ZK solution promoting Rollup architecture innovation
Following the release of Zeth, RISC Zero launched Kailua, aimed at providing an upgrade solution for optimistic Rollups with a hybrid ZK Rollup. Traditional optimistic Rollups usually require 7 days of challenge periods, leading to slow transaction finality, while ZK Rollups, although they can achieve rapid finality, incur high costs for continuously generating zero-knowledge proofs. Kailua combines the advantages of both, achieving a balance of cost and efficiency through a hybrid architecture. 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, reducing staking requirements and minimizing finality delays, thereby enhancing system efficiency and usability.
In Kailua's architecture, the dispute mechanism adopts a brand-new design. Firstly, its dispute resolution mechanism removes time limits, allowing validators ample time to generate proofs when encountering special situations like network interruptions, thereby enhancing the system's resilience. Even in extreme cases, RISC Zero zkVM's extended architecture can complete proofs within an hour. Furthermore, Kailua's on-demand validation feature allows developers to flexibly configure validation frequency, transitioning gradually to a fully validated Rollup model at lower costs.
Unlike ZK Rollups, 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. Additionally, 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 is fully open-source. Developers can use its command-line tools to deploy a local Optimism test network and quickly upgrade to a network that supports ZK fault proofs. Kailua also supports simulating fault proposals, helping developers understand how validators challenge erroneous states through zkVM, thus gaining a deeper understanding of its dispute resolution mechanisms. In the future, Kailua will further optimize cost and performance and expand support for more Rollup frameworks.
Summary
From the above, it can be seen that RISC Zero's zkVM product matrix is driving the development of zero-knowledge proof technology in multiple fields. Zeth and Kailua focus on optimizing the Rollup architecture, enhancing block validation efficiency and dispute resolution speed. Bonsai provides remote proof services, reducing hardware dependence and operational costs, allowing developers to build applications more efficiently. Blobstream Zero provides reliable support for the modular blockchain ecosystem by efficiently validating cross-chain data. Additionally, Steel reduces the gas costs of smart contract execution through a model of off-chain computation and on-chain verification.
Of course, while continuously improving the zkVM product matrix, RISC Zero is also driving innovation in the underlying technology of zkVM. 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 needing to embed it in the zkVM itself. This means developers can add new pre-compilation logic without modifying on-chain verification contracts or coordinating the configuration of provers, and without forking or making major changes to the zkVM to achieve performance optimizations. Additionally, by defining pre-compilation through applications, computing costs for proof generation can be reduced. For example, after integrating RSA pre-compilation, Automata reduced execution cycles from 39 million to 217,000, decreasing costs by approximately 180 times.
As zkVM technology continues to optimize, its development potential will gradually be reflected in multiple application scenarios. However, to better unleash this potential, it still relies on ecosystem collaboration and the practical performance of technology implementation.
