How does the RISC Zero product matrix help Ethereum move towards a ZK-based future?

Author: LINDABELL

At the recent Devcon conference, Justin Drake, a core member of the Ethereum Foundation, proposed the Beam Chain proposal, which plans to upgrade the Ethereum consensus layer through zkSNARK and zkVM technologies to improve the scalability, security and efficiency of the network. This vision has also brought the importance of zkVM back to the forefront. As a general zero-knowledge virtual machine, zkVM can handle complex calculations in a more flexible and efficient way, while getting rid of the reliance on traditional smart contract logic.

Driven by this trend, projects such as RISC Zero, Succinct and Cysic are regarded as important players in promoting innovation in this field. Among them, RISC Zero has developed a series of open source tools such as Zeth, Kailua and Bonsai with zkVM based on the RISC-V architecture, which not only improves the performance of block verification and Rollup, but also provides technical support for Ethereum ZK upgrades.

RISC zkVM Ecosystem Product Matrix: From Core Technology to Scenario Applications

RISC Zero is a zkVM implementation based on the RISC-V instruction set architecture. As a general zero-knowledge computing platform, it supports a variety of mainstream programming languages, such as Rust and C++, and can run almost any computing task. Compared with other zero-knowledge technology platforms, RISC Zero's provers and verifiers are completely open source, and developers can generate and verify proofs locally. In addition, RISC Zero's verifier is compatible with multiple platforms and can adapt to different blockchain ecosystems, simplifying the development process of decentralized applications.

In June this year, RISC Zero released zkVM 1.0. zkVM 1.0 not only supports multiple languages ​​and complex computing tasks, but also uses Continuations technology to divide large-scale computing into multiple small segments to achieve efficient parallel computing 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. The optimization content includes completely migrating the proof process to the GPU (80% completed), introducing a new RISC-V v2 circuit design, and special optimization for recursive circuits. At the same time, RISC Zero is integrating a series of acceleration modules for algorithms such as RSA, Keccak, and ECDSA to improve the performance of Ethereum-related tasks and encryption 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 by using the proof service. Through the Steel tool, complex EVM calculations can be transferred to the off-chain environment for operation while keeping the results verifiable, reducing the cost of on-chain execution. Blobstream Zero provides more possibilities for data sharing and verification in the modular blockchain ecosystem by bridging the Celestia data availability layer. Zeth: Prove 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. It can verify the validity of Ethereum blocks through zero-knowledge proofs without relying on traditional validators or synchronization committees. RISC Zero defines Zeth as a Type-0 zkEVM, which is fully compatible with the Ethereum protocol and improves development efficiency through code reuse.

Ethereum co-founder Vitalik Buterin divides zkEVM into four categories in the article "Different types of zk-EVMs", of which Type-1 strives to be completely and uncompromisingly equivalent to Ethereum; Type-2 is committed to being completely equivalent to EVM, but not completely equivalent to Ethereum; Type-3 is almost equivalent to EVM; 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. Test data shows that Zeth can generate block proofs at a speed of 1.1 MHz, and expand the GPU cluster through the "continuations" feature to increase 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 of a block containing 182 transactions is only $21.72, and the cost of each transaction is about $0.11.

At the same time, in the process of developing Zeth, the RISC Zero team made full use of components of the Rust ecosystem, such as revm, ethers, and alloy, so that developers can 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 level, Zeth provides efficient solutions for zk Rollup, light clients, and cross-chain bridges. The construction of traditional zk Rollup and zkEVM requires a lot of time and money, which is daunting for small teams. Zeth is based on a modular zkVM architecture, which allows developers to easily customize block verification logic. For example:

• zk Rollup: Zeth can quickly implement block proofs, which can shorten the development cycle of ZK Rollup and reduce capital investment.

• Light client: Verify the validity of blocks without rebuilding them, reducing operating costs.

• Cross-chain bridge: Zeth can verify the correctness of cross-chain data through ZKP without leaking sensitive information on the chain, which reduces the trust reliance on third parties and reduces the risk of cross-chain attacks.

In May of this year, Zeth successfully expanded to support the extraction of Optimism block data from the Ethereum mainnet, and generated ZKP to verify the correctness of blocks, and also supported verification on the chain. In other words, with the help of Zeth, Optimism can verify transactions more efficiently and resolve transaction disputes.

Bonsai: Allowing developers to generate proofs without using their own hardware

Bonsai is a remote proof service designed for zkVM applications, allowing developers to generate proofs without using their own hardware, thus solving the contradiction between limited computing resources and high costs on the chain. With Bonsai, developers only need to define the zkVM application and input data to be executed, and Bonsai can run the calculation in the background and generate the corresponding zero-knowledge proof. This process does not require developers to deploy additional hardware devices. At the same time, Bonsai utilizes a large number of GPU clusters to support parallel processing of multiple computing tasks. In addition, Bonsai provides simple and easy-to-use API and SDK interfaces, allowing developers to easily integrate it into existing systems, further reducing the difficulty of development.

Based on this remote proof service, RISC Zero launched the open source tool Bonsai Pay, which combines OAuth2.0 identity authentication and ZKP technology to enable users to send or receive tokens on the Ethereum network through Google accounts. For example, when Alice wants to transfer funds to Bob, Alice can enter Bob's Google email address and the transfer amount through Bonsai Pay. Bob can then log in to Bonsai Pay to enter his email address and complete Google account authentication. Bonsai Pay will use OAuth 2.0 to generate an authorization token to prove that Bob is indeed the holder of the email address. Bonsai Pay then calls the Bonsai Proof Service to generate a zero-knowledge proof that Bob's Google account is associated with the wallet address. After 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 the wallet address" through ZKP technology, while avoiding leaking any specific information of the Google account.

Another important application of Bonsai is the Bonsai ZK coprocessor. It uses zero-knowledge proof technology to transfer complex computing tasks from the chain to the off-chain, and generates tamper-proof proofs to ensure the correctness of the results. At the same time, the deployment of the Bonsai coprocessor is also very simple. Developers only need to write a zkVM application to handle the logic, and call Bonsai through a simple Solidity contract to run the calculation and verify the results. Throughout the process, the Bonsai proof service is responsible for generating zero-knowledge proofs for off-chain calculations, which can be verified on the chain.

The Bonsai ZK coprocessor is suitable for on-chain applications that require high performance and low cost. For example, in DAO governance, it can transfer complex voting calculations to the off-chain, significantly reducing on-chain gas fees. Bonsai DAO Governor reduces the gas cost per vote by more than 50% through the coprocessor, effectively improving governance efficiency and lowering the threshold for participation.

Boundless: Verifiable Computation Layer

In the traditional blockchain architecture, in order to ensure the validity of transactions, all nodes need to repeat all calculations for each transaction. Although this "global re-execution" mode can ensure security and consistency, it also brings extremely high computational costs. To solve this problem, RISC Zero launched Boundless, which allows a single node to generate a verifiable zero-knowledge proof after completing the calculation. Other nodes only need to verify the proof to confirm the result without repeating the calculation.

Boundless simplifies the verification process through recursive combination technology. It combines multiple small zero-knowledge proofs into an overall proof, so that the verifier only needs to check one total proof instead of verifying the proofs of all stages one by one. To further optimize the efficiency of generating zero-knowledge proofs, Boundless has built-in dedicated cryptographic acceleration circuits to optimize the efficiency of common tasks such as hash calculations and digital signature verification.

In addition, developers do not need to have an in-depth understanding of zero-knowledge technology to use Boundless. They only need to write applications in familiar programming languages ​​such as Rust or Solidity. Currently, Boundless has opened free access to developers. Developers can use 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-based cross-chain bridge that simplifies cross-chain data verification

Blobstream Zero is a zkVM-based cross-chain bridge jointly launched by RISC Zero and Celestia, aiming 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 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. In addition, Blobstream Zero can also provide support for ZK coprocessors. ZK coprocessors are essentially off-chain computing tools, so reliable data is required to perform calculations. Blobstream Zero can obtain data from blockchains such as Celestia, and can generate ZK proofs to prove that the transmitted data is reliable.

Steel: A new paradigm for smart contracts with off-chain execution and on-chain verification

Steel is an open source tool launched by RISC Zero that uses zkVM technology to achieve off-chain verifiable smart contract execution. With Steel, developers can transfer EVM operations from on-chain to off-chain execution, while generating zero-knowledge proofs to ensure the authenticity and verifiability of calculation results.

Traditional smart contracts require all logic to be fully executed on-chain, which not only has high gas costs, but also limits the development of complex applications. Steel's off-chain calculation and on-chain verification mechanism solves this problem. For example, in a simple smart contract, determine whether the ERC20 balance of an account is greater than 1 and increment the counter variable. Traditional methods require full execution of logic on the chain, while Steel completes the calculation and generates zero-knowledge proofs off-chain. Only the proof needs to be verified on the chain, without the need to repeat the contract logic.

Currently, RISC Zero has released Steel 1.0, and some partners have successfully developed applications using the tool. For example, in a contract call that processes about 400,000 SLOAD operations, Steel is used to transfer the calculation to the off-chain execution, and then the generated zero-knowledge proof is verified on the chain. The proof generation cost is less than $10, and the on-chain verification cost is less than 300,000 Gas.

Kailua: A hybrid ZK solution that promotes innovation in Rollup architecture

Following the release of Zeth, RISC Zero launched Kailua, which aims to provide an upgrade solution for optimistic Rollup to a hybrid ZK Rollup. Traditional optimistic Rollup usually requires a 7-day challenge period, resulting in slow transaction finality, while ZK Rollup can achieve finality quickly, but the cost of continuously generating zero-knowledge proofs is too high. Kailua combines the advantages of both and achieves a balance between 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, reduces staking requirements and reduces finality delays, thereby improving the efficiency and availability of the system.

In Kailua's architecture, the dispute mechanism adopts a completely new design. First, its dispute resolution mechanism removes the time limit, allowing validators to have sufficient time to generate proofs in special circumstances such as network outages, thereby enhancing the resilience of the system. Even in extreme cases, the extended architecture of RISC Zero zkVM can still complete proofs within an hour. In addition, Kailua's on-demand verification function allows developers to flexibly configure the verification frequency and gradually transition to a fully verified Rollup mode at a lower cost.

Unlike ZK Rollup, Kailua's design does not require continuous proof generation. For Rollups with low frequency of empty blocks or special contract requirements, Kailua provides a more cost-effective option. At the same time, Kailua also significantly reduces the staking cost requirements of Rollup. The staking amount of traditional optimistic Rollup increases linearly with longer finality cycles, while Kailua's optimized design fixes the staking requirements, allowing the system to maintain security and activity at a lower cost even over long periods.

Currently, Kailua is fully open source. Developers can use its command line tool to deploy a local Optimism test network and quickly upgrade it to a network that supports ZK fault proofs. Kailua also supports simulated fault proposals to help developers understand how validators challenge error states through zkVM, thereby gaining a deeper understanding of its dispute resolution mechanism. In the future, Kailua will further optimize cost and performance, and expand support to more Rollup frameworks.

Summary

From the above, we can see that RISC Zero's zkVM product matrix is ​​promoting the development of zero-knowledge proof technology in multiple fields. Zeth and Kailua focus on Rollup architecture optimization, improving block verification efficiency and dispute resolution speed. Bonsai provides remote proof services, reducing hardware dependence and operating costs, enabling developers to build applications more efficiently. Blobstream Zero provides reliable support for the modular blockchain ecosystem by efficiently verifying cross-chain data. In addition, Steel reduces the Gas cost of smart contract execution through the mode of off-chain computing and on-chain verification.

Of course, while continuously improving the zkVM product matrix, RISC Zero is also continuously promoting the innovation of zkVM underlying technology. Recently, RISC Zero zkVM released version 1.2, introducing a new pre-compilation method that allows developers to deploy pre-compiled logic with applications without being built into zkVM itself. This means that developers can add new precompiled logic without modifying the on-chain verification contract or coordinating the configuration of the prover, and without forking or significantly changing the zkVM to achieve performance optimization. In addition, by defining precompilation by application, the computational cost of proof generation can also be reduced. For example, after Automata integrated RSA precompilation, the execution cycle was reduced from 39 million to 217,000, and the cost was reduced by about 180 times.

With the continuous optimization of zkVM technology, its development potential will gradually be reflected in multiple application scenarios. However, if we want to better unleash this potential, we still have to rely on ecological collaboration and the actual performance of technology implementation.