Race to Scale Ethereum with zkEVM Rollups

As Ethereum aims for mass adoption, ZK-Rollup technology has emerged as a strong contender to scale the blockchain, lower transaction costs and improve throughput. Crypto Briefing breaks down four major ZK-Rollups compatible with the Ethereum Virtual Machine currently in development, each promising different benefits within the Ethereum ecosystem.

Manage Ethereum’s transaction fees

Ethereum faces scaling challenges.

Perhaps the biggest barrier to widespread Ethereum adoption is the high cost of using the network, which has become an existential problem for the blockchain. The rise of DeFi protocols and NFTs has increased the demand for block space on Ethereum. Most transactions cost a few cents in 2019, but during the peak of the bull run in 2021, activities such as minting NFTs on the blockchain would regularly fetch hundreds of dollars. As a result, many retail players found themselves priced out of the network and turned to other networks such as Solana, Avalanche or Binance Smart Chain. Today, despite a slowdown in network activity due to market conditions, simple transactions such as ETH transfers cost between $2 and $3, well above Ethereum creator Vitalik Buterins ideal target of less than $0.05 per transaction.

Rollups offer a way to alleviate congestion on the Ethereum blockchain. That’s because they outsource data off-chain, process it, and send transactions back to Ethereum instead of relying on the base chain to process each transaction’s computational data. With rollups, Ethereum only need to verify the evidence itself and not the entire data, which frees up block space. Summaries also allow transactions to be aggregated, allowing users to share gas charges.

Zero-Knowledge Rollups, also known as ZK-Rollups, uses cryptographic evidence called ZK-SNARKS (“zero knowledge succinct arguments of knowledge”) to show to the Ethereum mainnet that a transaction was processed. These zero-knowledge proofs can be verified quickly even though the underlying data will take a long time to analyze.

Some ZK-Rollup projects currently in development have announced their intention to be compatible with the Ethereum Virtual Machine, offering Ethereum developers a way to import their smart contracts into the rollup without modifying them. But like Buterin explained in a recent blog post, not all zkEVM projects are structured the same way: some optimize for full EVM composition, and others for fast throughput.

zkSync

Developed by Matter Labs, zkSync is one of the most anticipated zkEVM projects. With 2000 transactions per second, a 10-minute processing time between the rollup and the Ethereum network, and no upper limit on the value the rollup can safely handle, zkSync is a leading project in zkEVMs.

Despite its marketing, zkSync is not technically compatible with EVM, but rather with Solidity and Vyper, two coding languages ​​used on Ethereum. The difference, although small for users, is important for developers: i.a. the contract addresses may vary, handwritten EVM code may not be supported, and the debugging infrastructure may not necessarily be ported.

The collection is currently live on Ethereum’s testnet. The launch of the mainnet is expected to happen in three stages: “Baby Alpha” in November, where the system will be put through real money stress tests with no external projects involved; Fair Launch, which will welcome all Ethereum ecosystem projects but keep user access limited; and Full Alpha, expected before the end of the year. A zkSync token is expected, although details have yet to be announced.

StarkNet

StarkWare’s StarkNet is another major contender in the zkEVM arena. While StarkNet uses Cairo as its own coding language, a team is developing a Solidity to coding translator called the Cairo transpiler, which means that, just like zkSync, the digest will eventually be Solidity-compatible rather than EVM-compatible.

However, the similarities end there. StarkNet uses another type of cryptographic proof called STARKs (“scalable transparent knowledge arguments”). ZK-STARKs are theoretically more secure than ZK-SNARKs, but take longer to verify, take up more block space, and require more gas. StarkWare is the main driving force behind STARK-based technology development.

An approved version of StarkNet was published on the Ethereum mainnet in February 2022. The StarkWare team as well announced recently that StarkNet will have its own governance and utility token. While there are no official figures on StarkNet’s expected throughput at full capacity, StarkWare says the assembly could reduce gas fees on Ethereum by a factor of 100 to 200.

Polygon zkEVM

Polygon is an Ethereum scaling solution with a flexible framework that allows developers to build and connect Layer 2 infrastructure such as Optimistic Rollups and ZK-Rollups to the Ethereum network. In August 2021, Polygon acquired ZK-Rollup project Hermez Network for $250 million; the company announced a year later that it was working on its own ZK-Rollup, the Polygon Hermez, to work with the Proof-of-Stake Matic chain. Last month, Polygon announced that Polygon Hermez had changed its name to Polygon zkEVM and would go to the mainnet in early 2023.

Polygon claims that zkEVM will be able to handle up to 2,000 transactions per second and reduce transaction costs by 90%. The project’s code has been made open source; a public testnet is expected soon.

Unlike zkSync or StarkNet, Polygon’s ZK-Rollup does not intend to limit itself by being compatible only with the Ethereum code language, but with the EVM itself. Polygon zkEVM replicates EVM instead of mirroring it. This means that developers may still need to adapt code and tool frameworks to the digest, but to a lesser extent than on zkSync and StarkNet.

Alongside the ZK-EVM project, Polygon is also developing an Optimistic Rollup (Polygon Nightfall), a STARK-based ZK-Rollup (Polygon Miden), and a speed-optimized EVM-compatible ZK-Rollup called Polygon Zero.

Roll

ZK-Rollup aiming for the best integration with EVM is Scroll. A relatively new project, Scroll can be considered the true EVM equivalent; the only meaningful difference between the two is the runtime environment, meaning the subsystem where contracts are executed. However, the high composability comes at the price of a significant computational overhead, indicating that Scroll’s performance may be weaker than that of zkSync, StarkNet, and Polygon.

The Scroll team has yet to release details about the project, but on July 18, they asked developers to sign up to try the Scroll testnet, which is expected in Q3 2022. The Scroll team is developing the project in partnership with the Ethereum Foundation. The website claims that security, transparency and EVM equivalence are its top priorities.

More ZK Rollups

Other groups researching ZK-Rollups include the Ethereum Foundation’s Privacy and Scaling Explorations team and an as yet unnamed initiative affiliated with ConsenSys. Although research may contribute to existing projects and not necessarily lead to new ones, the recent breakthroughs in zero-knowledge secure technology may give rise to more ZK-Rollups in the Ethereum ecosystem. Although the Ethereum network still has a long way to go in terms of scaling, the emergence of new zkEVM projects should benefit both developers and users as they are presented with more solutions to suit different use cases.

Disclosure: At the time of writing, the author of this piece owned ETH and several other cryptocurrencies.