EIP-5988 Poised To Improve ZK-Rollups’ Compatibility With Ethereum

In a development that may reduce the costs of scaling up Ethereum, momentum is gathering behind a new plan for improving the interoperability between the Ethereum Virtual Machine (EVM) and ZK-powered rollups.

The proposal, dubbed EIP-5988, plans to make changes to the EVM, Ethereum’s core smart contract engine. This would improve interoperability between the virtual machine and ZK-powered rollups and reduce the costs incurred by zero-knowledge scaling solutions.

The proposal would implement the same hashing function used by the Poseidon hashing algorithm, which is designed to optimize the efficiency of ZK-proof-based systems. The upgrade would also enable greater interoperability between the EVM and a variety of hashing algorithms.

“Poseidon is one of the most efficient hashing algorithms that can be used in this context,” the proposal said. “Moreover, it is compatible with all major proof systems. This makes it a good candidate for a precompile that can be used by many different ZK-Rollups.”

Poseidon is currently used by several of Ethereum’s top Layer 2 scaling teams, including StarkWare, Polygon, and Loopring.

Over the past two years, Layer 2 rollups have emerged as the leading scaling solution for Ethereum. Rollups work by bundling together transactions on Layer 2 and later submitting them in batches for final verification on the Ethereum mainnet, sharing the associated fees between all of the transactions contained within each batch.

Optimistic Rollups

Arbitrum and Optimism, two optimistic rollup networks, currently enjoy a dominant share of Ethereum’s Layer 2 total value locked, representing 81% of TVL combined, according to L2Beat. They are also the fourth and fifth largest smart contract networks, ranking behind Ethereum, BNB Chain, and Tron.

Compared to ZK-based solutions, optimistic rollups trade improved EVM-compatibility ability for diminishing scalability. This means that developers can easily port their code from the Ethereum mainnet to optimistic rollups, unlike with rollups built using zero-knowledge proofs.

However, once ZK-based networks unlock greater EVM compatibility, they may surpass optimistic rollups due to their improved scalability, faster settlement, and privacy benefits.

EIP-5988

On Jan. 5, EIP-5988 was presented during an All Core Devs call for the first time. The ACD call is a bi-weekly meeting where leading developers in the Ethereum ecosystem discuss future upgrades for the protocol.

The proposal was presented by Abdelhmaid Bakhta, an exploration lead at StarkWare and one of EIP-5988’s authors.

“Poseidon is a ZK-friendly hash function,” Bakhta said. “It makes it very efficient in ZK contexts and it would enable a bunch of interesting use cases.”

Bakhta also emphasized the high expense currently associated with ZK-rollups generating storage proofs, attributing the issue to Ethereum’s failure to offer any ZK-friendly hash functions.

Developers Urge Caution

However, some researchers believe the proposal should be explored with caution, warning against making hasty tweaks to the EVM.

Dankrad Feist, an Ethereum Foundation researcher, warned that research into the proposed hashing function is “premature” and the code could pose unforeseen security risks.

“It’s a bit early to enshrine any arithmetic hash functions into the EVM because… of security concerns,” Feist said. “We just don’t know enough about them yet.”

While speaking on another matter during the call, Vitalik Buterin, the co-founder of Ethereum, urged developers to minimize making changes to Ethereum’s EVM where possible, arguing that Ethereum must provide a stable environment for developers.

“You have applications that are written in EVM code, and if the EVM changes, then those applications can’t change,” Buterin said.

The lack of interoperability between ZK-rollups and the Ethereum Virtual Machine sparked a race between top L2 teams to launch the first zkEVM in 2022. Polygon, Matter Labs, and Scroll are all working on private testnet deployments of zkEVM-based rollups.