TL;DR

●The main function provided by OP Succinct is to integrate ZKP into the modular architecture of OP Stack to complete the conversion of OP Stack Rollup into a fully verified ZK Rollup;

●If the end game of Ethereum's future expansion is to convert each Rollup into a ZK Rollup, OP Succinct aims to combine Rust and SP1 to implement the deployment of OP Stack's Type-1 zkEVM (fully Ethereum equivalent);

●OP Succinct Proposer mainly completes the parallel generation of proofs and proof aggregation and verification;

●OP Stack's existing system relies on a "7-day anti-fraud window". If a dispute arises, the transaction verification will be delayed for one week. OP Succinct uses ZK Proof of authenticity can shorten the time required to complete transactions, eliminating the need to extend the fraud prevention window;

●OP Succinct can greatly reduce transaction costs.

1. Recent Review: OP Mainnet Recent Situation and OP Stack and OP Labs

Image Source: Blockscout

1.1 Key Points of OP Mainnet Recent Development

According to news on March 30, 2024, OP Labs released "Proof of Fault" on the OP Sepoila testnet, and officially released the proof of fault on OP Mainnet on June 11, 2024, thereby advancing decentralization to the first stage, which allows the withdrawal of ETH and ERC-20 from OP Mainnet. Tokens that enable users to question and delete invalid withdrawals (including Base, Metal, Mode, and Zora) without the need for a trusted third party.

To ensure the security and trust of user assets, Optimism uses fault proofs to improve the accuracy and effectiveness of on-chain transactions and prevent malicious behavior. The principles include:

●      Data availability: Fault proofs first ensure that all data on Layer-2 is accessible and can be verified by Layer-1;

●      Challenge period: During a certain challenge period, anyone can object to the data on Layer-2.

If someone finds that the data on Layer-2 is inconsistent with the data on Layer-1, they can raise a challenge. Proof submission: If there are objections, the Layer-2 operator needs to submit proof to refute these objections and prove the correctness of its data; Finality: If there are no valid objections during the challenge period, or the Layer-2 operator successfully refutes the objection, the transaction will be finalized and considered valid.

1.2. The relationship and difference between OP Stack and OP Labs

OP Labs is the team or organization that develops the Optimism solution, and OP Stack is a technical framework for building and expanding the Ethereum second-layer network. The relationship between OP Labs and OP Stack can be understood as the relationship between developers and their development tools.

●      OP Labs:

OP Labs is a core contributor to the Optimism project, responsible for developing and maintaining the Optimism second-layer solution. It is a team or organization that focuses on building and improving technical tools related to Ethereum expansion, such as Optimistic Rollups. The main goal of OP Labs is to reduce the load on the Ethereum mainnet through a second-layer expansion solution, reduce transaction costs and increase transaction speed. OP Labs also works with other projects such as Succinct Labs to further advance Ethereum expansion technology, such as OP Succinct, which focuses on the optimization of zero-knowledge proofs.

OP Labs is the main team or organization that develops and maintains the Optimism network. Their goal is to build an efficient solution for expanding Ethereum, focusing on reducing transaction fees and increasing transaction speeds. Not only are they responsible for the development of Optimistic Rollups, they are also actively promoting new technologies related to zero-knowledge proofs, such as OP Succinc in collaboration with Succinct Labs.

●      OP Stack:

OP Stack is a modular architecture or technology stack for building and extending Ethereum's Layer 2 network. It consists of multiple customizable components that allow developers to build their own Layer 2 Chain according to specific needs. It provides a standardized way for developers to quickly build a Layer 2 extended network that meets specific conditions.

OP Stack is a modular framework developed by OP Labs. This framework provides the infrastructure for building a Layer 2 network, and developers can use OP Stack to quickly build different extended networks. Due to the modular design of OP Stack, it allows users to flexibly choose different verification mechanisms (such as Optimistic Rollups or ZK Rollups) to meet the needs of different projects.

OP Labs can be understood as the developer of OP Stack, which is a technical tool provided by OP Labs to help developers build and expand Ethereum's second-layer network.

Before understanding OP Succinct, you need to understand the four main components of each OP stack:1. op-geth: Get transactions from users and use these transactions to generate blocks and execute blocks; 2.
op-batcher: Batch user transactions and submit them to L1; 3. op-node: Read batch data from L1 and drive op-geth for state transition in non-sorter mode; 4.
op-proposer: Regularly publish output roots to L1 to capture L2 status, which is convenient for processing withdrawals.

2. Succinct Labs and OP Labs work together to inject ZK elements into OP Stack

Image source: Succinct blog

2.1 OP Succinct architecture composition

Combined with the content at the end of Section 1.2 above, "The four main components of OP Stack", OP Succinct is a lightweight upgrade of OP Stack, allowing the chain to use only blocks verified by ZK, while keeping the other three components unchanged (op-geth, op-batcher and op-node), OP Succinct It mainly consists of the following four components:

●      Range Program: This is a program that executes batch blocks. The program is written in Rust and is designed to be executed in zkVM;

●      Aggregation Program.: Aggregates the proof of the range program to reduce the on-chain verification cost. The program is also written in Rust and is designed to be executed in zkVM;

●      OP Succinct L2 Output Oracle.: A Solidity smart contract containing an array of L2 state outputs, where each output is a commitment to the L2 chain state. This contract already existed in Optimism's original system, but was modified to use proof of verification as the identity authentication mechanism;

●      OP Succinct Proposer: observes the batches of transactions published on L1 and controls the proofs of range programs and aggregation programs.

2.2 What kind of Ethereum scaling narrative does OP Succinct tell?

zkEVM Rollup is very difficult to build due to the deep cryptographic expertise. The OP Labs team has considered supporting proofs of various validity mechanisms when building the modular OP Stack, and has open-sourced Kona (see extended link 1) to implement the state transition function STF (functional logic of transaction state transition) under OP Stack Rollup through Rust, and finally use Kona and SP1 programs to generate OP Stack's zero-knowledge proof (ZKP), which means that in theory all chains of OP Stack can be upgraded and ZKP can be used.

The goal of SP1 (Succinct Processor 1) is to enable any developer to seamlessly integrate Type-1 zkEVM rollup using standard Rust code, and to seamlessly upgrade any existing OP Stack chain to Type-1 zkEVM rollup in just 1 hour through OP Succinct, and provide the high performance required by applications. The following advantages are obtained:

●      Fast confirmation of ZKP: shorten the proof delay to tens of minutes to "replace" the 7-day fraud proof questioning period;

●      Reduced cost and increased efficiency: the average cost of each transaction is as low as a few cents;

●      Switch OP Stack to ZK: Just deploy a smart contract and start a lightweight OP Succinct proposal service (see below) to generate proofs through API calls (including batch processors/sequencers, op-nodes, indexers, etc.);

●      Type-1 zkEVM: All functions related to OP Stack Rollup OP Succinct Rollup is applicable to compatible tools and smart contracts;

●       Improve scalability: Adopt customizable OP Succinct rollup, add new precompilation and modify Rollup logic.

According to the official GitHub introduction, the process only requires the installation of Rust, Foundry and Docker, that is, any existing OP Stack rollup can be upgraded to Type-1 zkEVM rollup, and the process is simplified to only two steps: 1. Deploy the ZK L2OutputOracle.sol contract; 2. Start the OP Succinct proposal service (see GitHub extension link 2 for the process).

Upgrade OP Stack Rollup to ZK Proof, source: Succinct blog

2.3 Use SP1 Reth to build Type-1 zkEVM

Succinct believes that EVM Rollup will be a maintainable zkEVM written in Rust in the future. Currently, OP Rollup faces three main problems: an excessively long 7-day fraud proof window, complex interoperability, and a mechanism that relies on multiple sets of data rather than fraud proofs in some cases. In addition, creating a zkEVM is a long process, so SP1 was developed to solve these problems.

SP1 is a high-performance 100% open source and fully open source customized zkVM that can verify the execution of any Rust (or LVM compiled language) program. According to public data, OP Succinct Stack has been successfully run on OP Mainnet, OP Sepolia and Base chain, and achieved a proof cost of $0.01-0.02 in Ethereum transactions (see extended link 3). It is hoped that all blockchain infrastructure (including Rollup, bridges, coprocessors, etc.) will be written in Rust (or other LLVM compiled languages) and utilize ZKP in the future.

According to the summary of Succinct's blog and open source GitHub content, the performance difference between SP1 and other zkVMs is mainly caused by several key factors:

1. Precompilation-centric architecture: SP1 supports a flexible precompilation system that can significantly accelerate a variety of operations (such as secp256k1 and ed25519 signature verification, sha256 and keccak256 hash functions), reducing the number of RISC-V cycles for many programs by 5-10 times. Its design goal is to provide performance comparable to ZK circuits while maintaining the flexibility and good developer experience of zkVM; 2. Fully open source: SP1 is 100% open source, allowing teams such as Argument and Scroll to implement custom precompilations, significantly reducing cycle counts and speeding up proof generation time; 3. Industry standard: Since its launch, the concept of precompilation within zkVM has become an industry standard and has been incorporated into projects such as RISC0, Valida, Nexus, and Jolt. SP1 is the only production-ready zkVM that widely supports precompilation of important cryptographic operations; 4. Efficient memory read and write: SP1 adopts an innovative memory proof method to achieve consistent memory for multiple proofs using a single challenge, avoiding the overhead of Merkle-ized memory; 5. Basic efficiency optimization: The use of lower blow-up factors and a new generation of lookup parameters (such as LogUp based on logarithmic derivatives), as well as the FRI variant in Plonky3, improves the utilization efficiency of the tracking area.

Image source: Succinct blog, see extended link 4 Appendix description

3. Can OP Succinct become OP Stack's trump card against ZK Stack?

Image source: @jtguibas

If Ethereum's expansion plan looks at OP in the short term and ZK in the long term, it will be regarded as an important milestone in Ethereum's development path if we assume that OP Succinct can succeed. OP Succinct provides an upgradeable path for ETH Rollups to convert from optimistic verification to zero-knowledge proof, which not only reduces transaction costs and increases transaction speed, but also retains the security and anonymity properties of ZK rollups, bringing new possibilities for the future outbreak of the application layer.

Among the four recognized Layer2 kings, OP Stack is slightly better than ZK Stack in terms of project ecosystem development at this stage. The Matthew effect may be further evident in the future. With the addition of OP Succinct, the traffic and potential of ZK Stack have been siphoned to a certain extent. If OP Succinct can be realized in the future, it may also have a certain impact on the traditional zkEVM Rollup.

However, according to the content publicly stated at this stage, it is not difficult to find from the operating logic of OP Succinct that how to ensure that developers can promptly discover the systemic risks caused by unknown vulnerabilities when modifying STF functions or adding new precompiled functions requires us to maintain long-term attention.