Blockchain infrastructure developer zkLink has unveiled Nexus, a layer 3 network built to connect multiple popular Ethereum rollup solutions, including zkSync, StarkNet, and Polygon zkEVM.
zkLink’s app-specific update packages inherit security from Ethereum using zk-SNARKs, and can connect to various universal zero-knowledge (zk) update packages.
By allowing tokens to be easily transferred between one zkLink combination to another, DeFi applications – including decentralized exchanges and NFT marketplaces – will be able to minimize liquidity fragmentation when sending transactions between different blockchains.
zkLink co-founder Vince Yang told Blockworks that Nexus will select only one of the layer 2 networks to perform the zk-SNARK verification process, reducing costs compared to performing verifications directly on the Ethereum mainnet.
“Nexus establishes a communication mechanism through Ethereum to coordinate and synchronize the state between different zk-based layer-2 networks, which represents the state of the Nexus network at each layer-2,” Yang explains.
Ethereum is the “host” for several zk layer-2 solutions, and each layer-2 solution can communicate with the Ethereum mainnet through its canonical bridge, Yang said. ZkLink Nexus deployed a smart contract on Ethereum and connected it to smart contracts connected to zk layer-2s.
“Nexus layer-3 posts proofs and off-chain layer-3 states to the contracts on the layer-2s,” which then posts state roots to Ethereum. “This communication is the fundamental guarantee to guarantee the national security of Nexus,” he said.
Yang notes that through this synchronization mechanism, Nexus can achieve Ethereum-equivalent security for different rollup aggregators without compromising security or introducing additional trust assumptions.
This synchronization mechanism is also a key factor in preventing deposit fraud, as it ensures that all deposit information remains accurate across multiple networks, preventing validators from double-signing a transaction.
Cross-zkRollup layer-2 state synchronization process | Source: zkLink
A key feature of this architecture is that it also enables customizable data availability, allowing multiple ways to store data, including options such as using Ethereum to store data via call data. It also provides data availability storage via validiums using on-chain layer-2 networks such as Celestia and EigenLayer or off-chain via a data Availability Committee (DAC).
The Nexus team is also working on a new technology called ‘Multiple Application Recursive Proof Verification’ or MARPV.
MARPV is the ability for recursive ZKPs to consolidate different verifications in the chain into a single verification that is then submitted.
It refers to the further recursive aggregation of evidence from different layer-3 combinations, reducing the number of on-chain verifications and consequently reducing costs, Yang noted. Because zkLink Nexus is an app-specific Layer-3 rollup solution, more than one Nexus Layer-3 rollup will be deployed by different apps.
Kalman Lajko, a senior software engineer at Matter Labs – the team behind zkSync – told Blockworks that zkLink, and applications that connect between multiple rollup ecosystems, solves the critical problem of fragmentation for the broader Ethereum community.
“This gives developers the ability to achieve greater scale, offer lower gas costs, and provide more app-specific customizability for their projects. The focus now must be on not creating additional assumptions of trust,” said Lajko.
Native token transfers between chains
Unlike some cross-chain interoperability protocols that send packaged versions of tokens from one chain to another, Nexus is designed to send native tokens to different zero-knowledge ecosystems.
Yang said tokens minted by the same application on different networks should be recognized as one. The design would allow users to trade on the zkLink layer, rather than just cross-chain transactions.
“Both mainstream and emerging currencies [will] find their trading pairs on zkLink Nexus, meaning users can achieve better trading depth and a wider range of trading pair selections through zkLink Nexus,” said Yang.
Upcoming work
Nexus currently uses Plonk, a category of zk-SNARKS, as its main zero-knowledge proof (ZKP) system. It is working to develop its own system based on recent advances from other proof systems, especially SuperNova and HyperNova, Yang notes.
According to Yang, no other projects use SuperNova or HyperNova, but there are many teams monitoring the progress of implementing these systems. This is largely due to the fact that SuperNova and HyperNova have not yet implemented production-ready technical states.
“On our roadmap, the zkLink team is working on implementing folding schemes and will implement it into the Nexus platform once it is ready for production,” Yang said.