Polygon launches EVM-equivalent ZK Rollup

The L2 scalability solution by Polygon is stated to be “fundamentally equivalent” to the Ethereum Virtual Machine (EVM), going beyond the simple EVM compatibility.

Image: Polygon blog

The announcement came during the Ethereum Community Conference (EthCC) in Paris, where the company presented its rollup as a “major leap forward,” claiming to have solved the blockchain trilemma.

“The holy grail of Web3 infrastructure should have three major properties: scalability, security, and Ethereum-compatibility,” said Mihailo Bjelic, co-founder of Polygon. “Until now, it has not been practically possible to offer all these properties at once. Polygon zkEVM is a breakthrough technology that finally achieves that, thus opening a new chapter of mass adoption.”

A concept coined by Vitalik Buterin, the blockchain trilemma claims that no network can achieve all three properties, security, scalability, and decentralization, at the same time. The developers always have to make some trade-offs, providing only two of three benefits. That might have been true until recently, but not anymore. ZkEVM by Polygon can have all three – or at least so the company claims.

Understanding zkEVM

To understand whether it’s possible for zkEVM to solve the blockchain trilemma, we should first take a closer look at what makes it different from other EVM rollups.

First of all, EVM equivalence is different from EVM compatibility offered by most Ethereum rivals. On an EVM-compatible chain, developers still need to modify their Web3 applications to use a different architecture, plus many tools designed for Ethereum won’t necessarily work on them. On an EVM-equivalent network, however, devs can continue to use the same code, tooling, apps, and smart contracts that they use on the Ethereum mainnet for much lower fees and higher TPS.

A meme comparing EVM compatible rollup vs EVM equivalent rollup.
Image: Optimism on Medium

Of course, EVM equivalence is hardly new to the blockchain industry – in November 2021, it went live on the Optimistic Ethereum mainnet. The main challenge was to implement a fully-featured zkEVM rollup.

ZK (zero-knowledge) rollups derive their name from being able to verify a batch of transactions by looking at a compressed, encrypted version of the data. However, unlike optimistic rollups, which are generally considered to be less complex technology, ZK solutions are application-specific, with their usage being restricted to certain types of smart contracts. Until now, since zkEVM can support all Ethereum’s smart contracts.

“Many believed that a zkEVM was years away, or not practical or competitive,” Jordi Baylina, co-founder of Polygon Hermez, recalled the feedback after the team's presentation at EthCC Paris in July 2021. “No one believed in us, but Polygon did.”

For now, zkEVM by Polygon relies on the centralized sequencer, which means that only one actor can publish transaction batches to chain. Yet it’s unable to compromise transactions, making it relatively safe compared to other centralized solutions. Polygon, however, said it is working on decentralizing this element of the network.

Besides allowing for seamless execution of Ethereum code, Polygon zkEVM is expected to cut transaction costs by 90% compared to the mainnet gas fees. It’s estimated that the network will be able to process 40-50 transactions per second, as opposed to Ethereum’s 15 TPS.

But Polygon isn’t an undisputed leader of the new technology. Two other teams, Scroll and Matter Labs, announced they will launch their own zkEVMs, setting ground for the heated race.

So far, Polygon has released part of the source code and roadmap for zkEVM. The public testnet is expected later this summer, while the mainnet launch is planned for early 2023.