ZKsync, praised by Vitalik, may really be underestimated.

Written by: Eric, Foresight News

On November 1st, Vitalik cited a tweet from the founder of ZKsync regarding the ZKsync Atlas upgrade and praised ZKsync for doing a lot of “underappreciated but valuable work for the Ethereum ecosystem.”

The market quickly reacted to Vitalik's words, with ZK prices soaring more than 2.5 times over the weekend. Tokens in the ZK ecosystem, including ALT (AltLayer), STRK (Starknet), SCR (Scroll), and MINA (Mina), all experienced significant increases.

After learning about the ZKsync Altas upgrade, we found that what ZKsync has done may really be underestimated.

Fast, small but expensive ZKP

The Ethereum Foundation has long been promoting ZKP (Zero-Knowledge Proof), which essentially aims to address the issues of slow verification speed and large amounts of verification data.

ZKP is essentially a mathematical probability problem. To illustrate its principle with a somewhat inaccurate example: suppose there is a person who claims to have solved the “four color problem.” How can we determine that this person indeed solved it without fully disclosing their solution? The solution of zero-knowledge proof is to select some parts of the entire graph and prove that there are no adjacent sections with the same color in these parts. Once the number of selected parts reaches a certain value, it can be demonstrated that the probability of this person having solved the four color problem has reached 99.99…%. At this point, we have achieved proof of “indeed solved the four color problem” without knowing the complete picture.

The above is what is commonly heard, “the zero-knowledge proof that proves that this thing has indeed been done without understanding how to do it.” As for why ZKP is being vigorously promoted in the Ethereum ecosystem, it is because the theoretical speed limit of ZKP is much faster than that of transaction-by-transaction proof, and the generated proof itself has a very small data size.

The speed is fast because ZKP does not need to understand the whole picture, it only needs to perform challenges. For example, to validate an Ethereum block, the current method is for each node to verify whether each transaction's execution address has enough balance and other basic issues. However, if only one node verifies each transaction through ZKP and then generates a “proof”, other nodes only need to verify that the “proof” itself is reliable. More importantly, the data size of this “proof” is very small, so the transmission and verification speed is extremely fast, and the cost of storing data is lower.

The reason why this technology, which has all the advantages, is not widely used is simply because it is too expensive.

Although ZKP does not require reproducing all processes, the challenge itself consumes a significant amount of computational power. If one were to crazily stack GPUs like in an AI arms race, faster speeds could be achieved, but not everyone can bear such costs. However, if it is possible through algorithmic and engineering innovations to reduce the required computational power and the time to generate proofs under low computation to a certain extent, achieving a balance between Ethereum's “price increase driven by technological innovation introducing more applications” and “the cost of purchasing GPUs for building nodes” can be feasible.

Therefore, many ZK concept projects or open-source developers in the Ethereum ecosystem focus on the combination of ZKP and Ethereum primarily on: generating ZK proofs at a lower cost and with faster speeds at a lower cost. Recently, the Brevis team achieved an average proof time of 6.9 seconds for Ethereum blocks (with 99.6% of proof times being less than the current average block time of Ethereum: under 12 seconds) using only half the cost of the SP1 Hypercube solution (64 RTX 5090 GPUs), which is why the Ethereum community is collectively praising it.

Although the cost of GPUs still exceeds $100,000, it has at least been proven that the speed has dropped to a level without ZKP, and everyone's task now is to reduce costs.

The Altas upgrade has achieved 1 second of ZK finality.

Perhaps many people do not know that the open-source zkVM ZKsync Airbender launched by ZKsync is the fastest single GPU verification zkVM. According to Ethproofs data, using a single 4090, the average verification time of ZKsync Airbender is 51 seconds, with a cost of less than one cent, both of which are the best results in zkVM.

According to data provided by ZKsync itself, not counting recursion, the average time for Airbender to validate the Ethereum mainnet using a single H100 and the ZKsync OS storage model is 17 seconds. Even including recursion, the total average time only takes about 35 seconds, which ZKsync believes is much better than requiring dozens of GPUs to achieve validation within 12 seconds. However, since there is currently only average data of 22.2 seconds with two GPUs, the actual quality has not yet been concluded.

However, all of this is not solely due to the efforts of Airbender; algorithm and engineering optimizations are just one aspect, and the deep integration with the ZKsync technology stack is the key to maximizing effectiveness. More importantly, it indicates that it is possible to achieve real-time proof on the Ethereum mainnet using a single GPU.

At the end of June, ZKsync launched Airbender, and the Atlas upgrade went live on the second-to-last day of the National Day holiday. This upgrade, which incorporates Airbender, has significantly improved ZKsync's throughput, confirmation speed, and costs.

In terms of throughput, ZKsync has made engineering optimizations for the sequencer: it has minimized the consumption caused by synchronization through independent asynchronous components; it has separated the states required by the virtual machine, the states required by the API, and the states needed to generate zero-knowledge proofs or validate zero-knowledge proofs on the L1 layer, thereby reducing unnecessary overhead of the components.

After on-site testing with ZKsync, the TPS for high-frequency price updates, stablecoin transfers in payment scenarios, and native ETH transfers reached 23k, 15k, and 43k respectively.

Another huge qualitative change comes from Airbender, which helps ZKsync achieve a 1-second block confirmation and a cost of 0.0001 dollars per transaction. Unlike verifying mainnet blocks, ZKsync only verifies the validity of state transitions, so the computational load is much smaller than verifying mainnet blocks. Although achieving ZK finality for transactions still requires validation on the mainnet to ultimately realize L1 finality, the presence of ZK verification indicates the validity of the transaction, while L1 finality is more like a procedural guarantee.

In other words, transactions executed on ZKsync only need ZKP verification to be fully confirmed as valid, and with significantly reduced costs, ZKsync has achieved, in their own words, application scenarios that only Airbender can bring.

First of all, there are on-chain order books, payment systems, exchanges, and automated market makers, etc. Airbender enables the system to verify and settle at extremely fast speeds, reducing the risk of rollbacks for these applications on-chain.

The second point is something that many current L2s cannot achieve, which is the ability to interoperate between public and private systems (such as ZKsync's Prividiums) without the need for a third party. Prividiums is the infrastructure launched by ZKsync to help enterprises establish private chains. For enterprises, the requirements for blockchain are fast settlement and privacy. Fast settlement goes without saying, and the inherent privacy of ZKP allows the enterprise's private chain to verify transaction validity without exposing the ledger information of the chain itself when interoperating with public chains. The combination of the two even meets the regulatory requirements for settlement time in on-chain securities and foreign exchange trading.

This may also be the reason why ZKsync has become the second largest tokenized RWA asset issuance network after Ethereum.

ZKsync is also proud to state that all of this can only be achieved under the Altas upgrade: the sequencer provides low-latency transaction packaging, Airbender generates proofs within a second, and then Gateway verifies and coordinates cross-chain messages.

Connect L1 and L2

As per the tweet retweeted by Vitalik, ZKsync founder Alex believes that after the Altas upgrade, Zksync has truly achieved interoperability with the Ethereum mainnet.

The current final confirmation time for transactions on ZKsync (about 1 second) is shorter than the Ethereum mainnet block time (average 12 seconds), which means that institutional and RWA transactions conducted on ZKsync are essentially consistent with those on the Ethereum mainnet, just waiting for confirmation from the Ethereum mainnet. This implies that ZKsync does not need to replicate liquidity centers on L2 and can directly utilize the liquidity from the mainnet, as the cross-chain interaction between ZK Rollup and the mainnet does not require a 7-day challenge period like OP Rollup, and the Altas upgrade further accelerates the speed based on the original foundation.

This has improved the recent fragmentation issue of L2 that the Ethereum community has been discussing, where L2 and L1 are no longer two separate chains, but have been integrated through fast confirmations and validations, allowing L2 to truly be called an “expansion network” for the first time.

When ZKsync and Scroll first launched their mainnet, the transaction confirmation speed and gas fees were no different from or even higher than those on the mainnet. This was essentially due to the lack of systematic optimization for the ZKP algorithms and engineering at the time of launch, which resulted in slow verification speeds and high costs. This led to a trust crisis regarding ZK Rollups. To this day, Optimism and Arbitrum are slowly transitioning from OP Rollups to ZK Rollups (or a combination of both). The further improvements in cost and speed of ZK Rollups like ZKsync, along with the decentralized ZKP of Scroll, have shifted from being “nonsense” to results that are worth looking forward to.

From being universally criticized to becoming a hot commodity, ZK has ushered in a new dawn. After the multi-signature implementation of the sorter and cross-chain bridge is fully decentralized, it may truly be able to achieve what Dragonfly managing partner Hasseb Qureshi described as “can't be evil.”