[Feature Request] <ERA-IP-10: Introducing Cross-Chain Interoperability in zkSync>

[tudorpintea999]

Network

zkSync Era

Provide a brief description of the feature you would like to see implemented.

Abstract
This ERA Improvement Proposal (ERA-IP) suggests the introduction of cross-chain interoperability in zkSync using atomic swaps. The objective is to enable assets to be exchanged between zkSync and other blockchains in a trustless manner, expanding the utility and reach of zkSync.

Motivation
zkSync is a leading layer-2 scaling solution, but its ecosystem remains somewhat isolated from other blockchains. As the decentralized finance (DeFi) space grows and becomes more interconnected, enabling cross-chain interactions will position zkSync as a central hub in the multi-chain universe.

Specification
Atomic Swaps: Implement atomic swaps to allow trustless exchange of assets between zkSync and other blockchains.

New Contract Type: Introduce a new smart contract type, CrossChainContract, which will handle the logic for cross-chain interactions.

Fee Structure: Transactions involving cross-chain interactions will have a separate fee structure, accounting for the increased complexity and potential cross-chain gas costs.

Supported Chains: Initially, support will be added for Ethereum, Binance Smart Chain, and Polkadot, with plans to expand to other chains based on demand.

Rationale
Atomic swaps have been proven to be a reliable method for trustless cross-chain interactions. By integrating this into zkSync, we can ensure that users can seamlessly move assets across chains without relying on centralized bridges or third parties.

Backwards Compatibility
This proposal introduces new functionalities but does not alter existing zkSync operations. As such, it remains backward compatible with current zkSync implementations.

Test Cases
Cross-Chain Transaction Validation: Ensure that transactions involving CrossChainContract are validated and processed correctly across chains.

Fee Assessment: Confirm that fees for cross-chain interactions are consistent with the proposal and are competitive with other cross-chain solutions.

Security Considerations
Cross-chain interactions introduce new attack vectors, especially around atomic swaps and potential chain reorganizations. Comprehensive auditing and testing will be essential to ensure the security of zkSync during cross-chain operations.

Copyright Waiver
This ERA-IP is released into the public domain.

This ERA-IP proposes a new feature to enhance the interoperability of zkSync with other blockchains, positioning it as a central player in the multi-chain DeFi space.

Who does this feature request benefit the most (users, developers, protocol, etc.)?

The feature request for introducing cross-chain interoperability in zkSync using atomic swaps benefits multiple stakeholders:

1. Users: Cross-chain interoperability allows users to seamlessly move their assets across different blockchains. This provides them with more flexibility, access to a broader range of decentralized applications (dApps) and services, and potentially better liquidity and yield opportunities.

2. Developers: Developers can create dApps on zkSync that can interact with other blockchains, expanding the potential user base and use cases for their applications. It also allows them to leverage the unique features and advantages of multiple chains.

3. zkSync Protocol: By becoming a hub for cross-chain interactions, zkSync can increase its transaction volume, attract more projects to its ecosystem, and solidify its position as a central player in the multi-chain universe. This can lead to increased adoption and recognition of zkSync.

4. DeFi Ecosystem: The broader DeFi ecosystem benefits from enhanced liquidity, more interconnected dApps, and a more unified user experience across different chains.

5. Other Supported Blockchains: Blockchains that are supported for cross-chain interactions with zkSync can see increased activity and usage, as assets and operations can flow more freely between them and zkSync.

In summary, while all stakeholders benefit, the primary beneficiaries are likely to be users (due to increased flexibility and opportunities) and the zkSync protocol itself (due to increased adoption and transaction volume).

Additional Details

No response

[kelemeno]

Hi, thank you for this proposal! We are definitely thinking along these lines, unified liquidity across hyperchains will be very important. However, due to security reasons, we would like to do this in another way. Our approach will focus general message passing between hyperchains (rollups, validiums, zkPorters) that are all settling on the same L1. Assets (such as ether) can be locked on L1 and trustlessly passed around the ecosystem. Other message passing will also be possible, not just asset transfers or swaps, the system will have general message passing. The security of the message passing will be guaranteed by storage proofs. For more details check here:
https://era.zksync.io/docs/reference/concepts/hyperscaling.html

For trustless swaps between different L1s and ecosystem we think HTLC are an alternative.