When ZK technology becomes more popular in areas such as Hybrid Rollup, ZK cross-chain bridges, and ZK hardware acceleration, the Layer2 market will see new vitality. This article is sourced from Haotian and compiled, translated, and written by Foresight News.
Table of Contents:
Hybrid Rollup
Trust Mechanism Based on ZK Cross-Chain Bridge
Conclusion
Many people think that ZK-Rollup is the endgame of Ethereum Layer2. However, as research goes deeper, I have found that the true endgame is not the ZK-Rollup form, but the ZK technology itself.
In theory, OP-Rollup can also use ZK technology to reduce the 7-day challenge period and even eliminate the MPC multi-signature governance flaw. How should we understand this? This article will discuss this topic using “MetisL2” and its underlying hardcore project “ProjectZKM” as examples.
In a previous article, I also explained that the potential of “ZK technology” for Layer2 scaling has only been partially explored, and there is still great potential for fully trustless and interactive operability across the entire chain. In specific Layer2 application scenarios, it can directly bring two major impacts:
1. Cross-chain transactions between Layer2 and Layer1 can be directly based on the ZK underlying technology for secure asset settlement. By using ZK technology, OP-Rollup can significantly shorten the 7-day waiting period for fund withdrawal challenges.
2. The Prover verification system of Layer2 and the Rollup verification contract of Layer1 can establish a trusted environment for cross-chain construction. In theory, it is possible to no longer rely on centralized or semi-centralized MPC multi-signature models to ensure security.
In fact, “MetisL2” as a Layer2 chain based on the OP-Rollup technology framework has already realized the normalization transition of the underlying architecture in these two dimensions through the underlying ZK technology:
1. On one hand, by optimizing the user experience of Withdrawal by using the hybrid Rollup framework of OP-Rollup+ZK-Rollup, it can speed up the release of liquidity by reducing the 7-day waiting period.
2. On the other hand, by using Metis Layer2 as an experimental target to gradually implement the “trustless” framework of “ProjectZKM” in cross-chain operability among different chains, ZK is used as the underlying infrastructure to build a decentralized co-processor as a trusted entity to generate proofs, verify proofs, and manage communication and trust mechanisms among cross-chain blockchain nodes. How to do it specifically?
Under normal circumstances, a Layer2 is either an OP-Rollup structure based on optimistic 7-day challenge period proofs, or a ZK-Rollup structure based on ZK-SNARKs with single-block finality proofs.
The former has fast batch transaction speed and low fees, but the drawback is that users need to wait for a 7-day challenge period when withdrawing funds from Layer2 to Layer1 because, according to the optimistic batch principle of OP-Rollup, the withdrawal of funds can only be considered secure if it is not challenged within 7 days.
The latter, ZK-SNARKs’ proof transmission structure, can achieve asset security confirmation in a single block. However, in addition to the cost of DA for batch transactions, it also adds additional costs for Prover system calculations. Moreover, the development threshold for the Layer2 ecosystem is higher, resulting in slower ecosystem development.
So, how can we achieve both the usability of the overall OP-Rollup structure and avoid the 7-day challenge period (locking liquidity) limitation? The answer is to process the transactions from Layer2 back to the mainnet in separate “channels.” Common transactions go through the OP-Rollup channel, while special Withdrawal transactions go through the ZK-Rollup channel. This way, the best solution is found by combining the advantages of OP and ZK.
Metis has already implemented the hybrid Rollup solution in its chain operation process, and the “ProjectZKM” underlying project, incubated and developed by the Metis technical team, provides this hybrid Rollup capability. Metis team has encountered some inherent normal problems in operating Layer2, and in addition to tackling the decentralized Sequencer problem, they also aim to solve a series of problems in the development process of layer2, such as “MPC semi-centralization” and “locking liquidity” through ZKM.
In this sense, it may seem abstract to some people. The reason is that these services are currently in the upstream of the Layer2 technology service supply chain and, although they are hardcore, they have not been widely adopted, so they still sound unfamiliar.
ZKM and RISC Zero both aim to provide higher-level security consolidation services for Layer2 projects based on the underlying ZK technology framework. Currently, ZKM provides the ZK-Rollup pipeline service needed for the hybrid Rollup of Layer2, and there is also an Entangled Rollup protocol underlying it to provide unified liquidity management services.
In fact, service providers in the upstream of ZK technology, such as ProjectZKM, RiscZero, and SuccinctLabs, are all promoting similar technical solutions to further reduce the differences between OP-Rollup and ZK-Rollup and reduce the liquidity loss caused by the 7-day challenge waiting period, which is a challenge that has not been battle-tested. Projects like Metis, Fraxchain, Aztec, and Ola have been exploring the implementation of such hybrid Rollup solutions.
Currently, most Layer2 projects are criticized for the problem of the mainnet Rollup contract being controlled by a semi-centralized MPC security governance committee, which means that the security of most Layer2 projects is still in Vitalik’s Stage 0.
Service providers like ZKM and RISC Zero can theoretically enable every chain with smart contract functionality to achieve decentralized trust environments for cross-chain bridges without MPC multi-signatures.
The principle is simple: ZK-SNARKs allows consensus nodes of two chains to establish direct communication. When the nodes of Chain A receive transactions and ZKP proofs submitted by Chain B nodes, they can independently verify the validity of the ZKP proofs and accept the validity of the proofs submitted by Chain B. The entire process is achieved solely through zero-knowledge proof algorithms without the need for third-party control.
As for the co-processor that schedules communication between nodes, it can be implemented using a decentralized open-source architecture, thus completely solving the “centralization” problem of Rollup cross-chains.
Since Ethereum has complete smart contract functionality, theoretically, all Layer2 projects on Ethereum have the basic conditions for cross-chain based on ZK technology. In an ideal situation, all Layer2 deployments would use the same set of ZK technology frameworks for cross-chain solutions, and other Layer1 and even Layer3 chains would also be incorporated into this network communication framework. Then, the future Ethereum public chain would become a universal settlement layer in a fully connected environment.
The reason why most Layer2 projects are not willing to abandon MPC multi-signature governance is mainly due to security considerations, and the fundamental reason, in my opinion, is that the popularity of decentralized sequencers, decentralized Provers, and decentralized zkBridges, and other basic components and services at the Layer2 level are not in place. In this situation, retaining a centralized or semi-centralized security governance committee has become a safer governance method.
However, in the long run, as Layer2 decentralization components become more popular, the security governance methods of Layer2 will inevitably be criticized, and a cross-chain settlement solution based on the ZK underlying framework will become necessary. The future development potential of the ZK technology infrastructure is imaginable.
To put it bluntly, the current development of Ethereum Layer2 has fallen into a development bottleneck: either rely on a phenomenally successful project from the Layer2 or Layer3 application ecosystem to boost market confidence in Layer2, or rely on further decentralization of key components such as Sequencers, Provers, and zkBridges to continue the technical narrative.
To follow this path, the development direction of Layer2 will not be proven false, and it can also extend to the development of ZK hardware acceleration, ZK+DePIN support for PC, mobile devices, IoT, ZK tamper-proof cloud computing data protection, decentralized ZK Prover system construction, and optimization of computing resources, among many other narrative directions.
In fact, at the intersection of the AI, ZK, and DePIN tracks, there are already many similar projects that are increasingly prominent.
Metis has the same development mindset in Layer2 and the original intention of the hardcore ZKM project, which is to make ZK technology more universally applicable to every aspect of the global Layer2 market. In addition to Metis, I have also noticed other projects, such as “cysic_xyz,” which continues to work on ZK hardware and chip acceleration, and “ola_zkzkvm,” which gradually implements the decentralized computing power system for ZK Provers.
In conclusion, I want to reiterate my view that the application of ZK technology in the Layer2 field is just the tip of the iceberg. When ZK technology becomes more widely used in areas such as hybrid Rollup, ZK cross-chain bridges, and ZK hardware acceleration, it will undoubtedly bring new vitality to the Layer2 market.
After all, it will take a long time for the entire Layer2 market to fully adopt this ZK-based upgrade and achieve normalization.