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The battle between ZK and OP routes in RaaS: Why ZK-RaaS is the better choice?

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ZK-PoW and NCRC protocols enhance the advantages of ZK-Rollups.

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Source: Opside

TL; DR

ZK-Rollups have the following advantages over Optimistic Rollups:

· Compressed transaction data saves more L1 gas costs

· More secure, no need to trust

· Faster transaction confirmation speed, as well as shorter withdrawal time.

In addition to these benefits, ZK-RaaS also has advantages in the following areas through network effects:

· ZK-RaaS provides scalable computing power for massive ZK-Rollups through ZK-PoW, reducing the cost of ZKP calculations. ZK-PoW is a decentralized prover network that supports multiple chains and rollups.

· Thanks to the faster transaction confirmation speed (in minutes) of ZK-Rollup, native cross-Rollup communication (NCRC) can be achieved between ZK-Rollups, solving the problem of fragmented liquidity. The NCRC protocol is implemented.

What is RaaS?

Rollups-as-a-Service (RaaS) provides an abstraction layer on top of the Rollup framework and SDK, making it easy to deploy, maintain, and build custom, production-grade specific application Rollups (AppRollups). Similar to software-as-a-service products, RaaS allows developers to focus on building the application layer, turning a process that previously required multiple engineers and dozens of hours into a 10-minute no-code deployment process.

There are two main types of Rollup, Optimistic Rollups and ZK-Rollups. They differ in transaction verification and dispute resolution, and have different advantages and disadvantages. Based on the type of Rollup provided, this article divides RaaS into Op-RaaS and ZK-RaaS.

One, Cost

ZK-Rollups have lower L1 gas costs compared to Optimistic Rollups

One of the main goals of Rollup solutions is to increase the throughput of transactions on Ethereum and reduce users' gas fees. Optimistic Rollups and ZK-Rollups achieve this goal by batching transactions and periodically submitting them to the mainnet. Therefore, they both need to pay gas fees for the data submitted to L1.

Due to the use of fraud proof, Optimistic Rollups must publish all transaction data on the chain. Therefore, they require more Gas to submit data batches to the main chain.

Due to the efficient data compression technology of ZK-Rollups (for example, using indexes to represent user accounts instead of addresses, which can save 28 bytes of data), this helps to reduce the cost of publishing transaction data on the underlying chain.

Therefore, ZK-Rollups can save more L1 Gas compared to Optimistic Rollups.

ZK-RaaS reduces ZKP computation costs through large-scale miner participation

However, ZK-Rollups require additional computational costs for generating zero-knowledge proofs. This is exactly what ZK-RaaS aims to solve.

With the large-scale implementation of ZK-Rollup, the generation of ZKP requires a large amount of hardware and mining machines such as CPU, GPU, FPGA, etc. to provide computing power. Opside (https://opsi.de) has also proposed the concept of ZK-PoW, introducing the role of miners to participate in the maintenance of zkEVM nodes and the calculation of ZKP. The Opside ZK-PoW protocol will be deployed on multiple chains, including but not limited to Ethereum, BNB Chain, Polygon PoS, and Opside Chain itself.

In order to encourage more miners to participate in ZKP computation tasks, Opside has proposed ZKP's Two-Step Submission Algorithm. The PoW reward share corresponding to a ZKP will be allocated to the submitter, i.e. the miner, who submits a valid ZKP according to certain rules.

Submit proofhash: Within a time window, multiple miners are allowed to participate in the calculation of zero-knowledge proof for a certain sequence. After each miner calculates the proof, they do not directly submit the original proof, but calculate the proofhash of (proof / address) and submit it to the contract.

Submit ZKP: After the time window, miners submit the original proof and verify it with the previously submitted proofhash. Miners who pass the verification can receive PoW rewards, and the reward amount is distributed according to the proportion of the miner's staked amount.

In Opside, the two-step ZKP commitment algorithm has implemented parallel computation and serial submission of ZKP, allowing miners to execute multiple ZKP generation tasks simultaneously, greatly accelerating the efficiency of ZKP generation.

二、交易最终确定性与资金效率

Translation:

2. Finality of Transactions and Efficiency of Funds

· Optimistic Rollups: There is a challenge period of up to 7 days, and transactions will not be finally confirmed on the main chain until the end of the challenge period. Therefore, Optimistic Rollups has a high delay in transaction finality.

· ZK-Rollups: The advantage of ZK-Rollups is the low delay in transaction finality, typically taking only a few minutes or even seconds. Once the node operator verifies the validity proof, it will result in a state update.

Due to the challenge period in Optimistic Rollups, users are unable to withdraw funds before the expiration date, causing inconvenience. ZK-Rollups, on the other hand, do not have a challenge period, providing users with better fund/liquidity efficiency and the ability to withdraw funds at any time.

Three, Shared Liquidity

It is worth mentioning that, due to the fast confirmation of transactions in ZK-Rollups, it is possible to achieve trustless communication between ZK-Rollups, thereby enabling all Rollups to share asset liquidity. However, due to the existence of fraud proofs and a 7-day challenge period, it is not practical for Optimistic Rollups to achieve trustless native communication between them.

The NCRC (Native Cross Rollup Communication) protocol of the ZK-RaaS platform Opside provides a trustless Rollup interoperability solution. Unlike adding a third-party bridge on each Rollup, the NCRC protocol transforms the native bridge of ZK-Rollup at the system level, enabling direct communication between different ZK-Rollups. This approach is more concise and thorough, inheriting the absolute security of the native bridge and avoiding the system complexity and trust cost brought by third-party bridges.

NCRC has been launched on the testnet, and users can directly experience it at https://pre-alpha-assetshub.opside.network/.

Four, Security

Optimistic Rollups: Fraud proofs ensure the validity of transactions by having honest validators protect the blockchain network. If there are no honest nodes to challenge invalid transactions, malicious actors can steal funds, making these optimistic rollups insecure.

ZK-Rollups: ZK-Rollups verify transactions using zero-knowledge proofs instead of relying on honest validators. The advantage of ZKP is that it provides security through mathematical proofs rather than human participants. Therefore, ZK-Rollups are trustless.

Although fraud proof of Optimistic Rollups is theoretically feasible and a few Rollups are already in operation, the risks of this security model will gradually be exposed as time goes by and the number of Optimistic Rollups increases, becoming a gray rhino or even a black swan. Running an honest validator requires cost and most of the time there is no profit. When Op-RaaS creates numerous Optimistic Rollups, it is difficult to ensure that every Rollup has honest nodes, especially those that are not in the spotlight.

And the security of ZK-Rollups is trustless, as they do not rely on users or validators to challenge fraudulent transactions, but instead provide security guarantees through mathematical proofs.

Summary

Whether it's ZK-RaaS or Op-RaaS, developers don't need to manage complex software and hardware to have their own Rollup application chain.

Represented by Opside (https://opsi.de), the ZK-RaaS platform has launched the ZK-PoW and NCRC protocols, making the advantages of ZK-Rollups even more apparent.