Polygon has announced the launch of its zkEVM public testnet; Matter Labs’ zkSync mainnet is planned in the coming weeks.
The battle to build a workable Ethereum virtual machine (EVM) on a zero-knowledge proof-based rollup (zk-rollup) is heating up, with Polygon announcing today that their EVM-equivalent project is now running on a public testnet.
Rival zkSync has been running its EVM testnet since February and is to launch its mainnet by the end of October.
The announcement at the Polygon Connect event in Bogota, Colombia — on the margins of DevCon, the largest Ethereum developer conference — proves that zkEVMs are just around the corner, according to Polygon co-founder Mihailo Bjelic.
The introduction of zkEVMs is seen as the most likely outcome for Ethereum scaling. However, Ethereum co-founder Vitalik Buterin warned in December 2021 that “it will take years of refining and audits before consumers are totally comfortable keeping their assets in a ZK-rollup running a full EVM.”
Zero-knowledge rollups take transaction execution off-chain for verification before batching those transactions for settlement on Ethereum.
The system has the potential to meet numerous important blockchain design goals, including near-infinite scalability, excellent security guarantees, and a familiar building experience for Ethereum developers.
Unlike optimistic rollups, zk-rollups do not necessitate extensive withdrawal periods associated with fraud proofs, which might result in higher capital efficiency.
Polygon asserts that it is the first general-purpose, EVM-equivalent, and completely open-source zk-rollup. Major DeFi platforms like Aave and Uniswap, as well as the social network Lens, which is now on Polygon’s PoS chain, will be among the protocols to test the zkEVM testnet.
Compatibility vs. equivalence
Polygon zkEVM is “Ethereum-equivalent,” according to the Polygon team, which implies that all existing Ethereum smart contracts, developer tools, and wallets will operate effortlessly.
However, a peek at the project’s Github source repository suggests otherwise, according to Steve Newcomb, chief product officer of zkSync. As of Monday, 125 opcodes (abbreviated from operation codes) were missing from the repository.
“Every other weekend, I study Polygon’s source code…It’s simply not conceivable that they have [the prover] operating for general purpose usage”, according to Newcomb
ZkSync’s EVM, branded zkSync 2.0, is described to as “Ethereum-compatible” since just three opcodes are intentionally excluded to improve efficiency.
“We think it’s a non-issue,” Newcomb said last month on the Bankless podcast. “It’s extremely simple to port to us,” he noted, emphasizing that dapp developers will find nothing missing in zkSync’s implementation.
Polygon and zkSync offer an advantage over non-EMV-compatible zk-rollup technology from Starkware and Loopring in that existing code written in solidity for Ethereum does not need to be transcompiled for usage on the rollup.
And it’s clear that they won’t be the only games in town. Aside from Scroll, a previously revealed EVM-equivalent zk-rollup project, fresh entrants like Taiko, whose team includes Loopring and GameStop alumni Matt Finestone, can be expected.
Matt Fiebach of Blockworks Research sees a pattern developing and predicts that additional EVM-equivalent ZK rollups will arise.
“Oh man there are gonna be 50 EVM equivalent ZK rollups next year aren’t there,” he said.
Polygon open-source strategy
The so-called “prover” — cryptographic logic that signs off on transactions while protecting users’ anonymity — is critical to the operation of zk-rollups. The contending teams are already at odds over the speed and design of the prover.
“The Polygon zkEVM testnet also contains a totally open-sourced zk-Prover – the first of its type to be publicly disclosed,” Polygon stated in a statement.
Except than the prover, the zkSync team intends to open-source their EVM when it goes on mainnet. That will have to wait until the project starts decentralizing through its own set of validators and, presumably, by the issuing of a coin.
“We don’t have a date yet because we’re really conservative about releasing dates,” Newcomb said, adding that the team will update a public roadmap when more information becomes available.
According to Newcomb, there are several benefits to using a standard prover, such as native bridges that aren’t actually bridges at all, but “pure cryptography,” making it intrinsically more secure than existing bridges that have been so vulnerable to hacking.
From the testnet to the mainnet
Polygon aims to launch the mainnet version of its zkEVM in “early 2023,” according to a Polygon spokeswoman.
According to zkSync’s Newcomb, that is an exceedingly optimistic objective.
“I just hope to God they’re not hurrying through testnet in an effort to catch up with us,” he told
“You can’t do a security audit in that amount of time. You can’t even book a meeting with a security company to schedule them in that amount of time.”
In a second statement today, zkSync noted in a blog post that they are going beyond layer-2, to what they call “Pathfinder,” a layer-3, which is also targeted for early 2023.
As numerous firms battle for what Polygon’s Bjelic has dubbed the “Holy Grail of blockchain scalability,” the quest for zk-rollup adoption, which was previously viewed as a marathon, is now becoming more of a sprint.
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