Ethereum Interop Layer Contracts

This repository contains the smart-contract core of Ethereum Interop Layer, a trust-minimized, cross–chain interoperability protocol. EIL enables users to interact with the entire Ethereum ecosystem instead of separate fragmented chains cross-chain UserOperations — moving tokens, making calls, or paying gas — without relying on trusted relayers or bridges

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Table of Contents

• Background
• Vision & Goals
• Core Contracts
• How It Works
• Trust Model & Security
• Getting Started
• Contributing
• License

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Background

EIL is motivated by the fragmentation of the L2 ecosystem. Each rollup feels like a separate chain with its own assets and applications, which hurts the user experience.

EIL’s goal is to unify that experience so that interacting across chains feels like interacting on a single Ethereum chain.

Unlike solutions that depend on third-party relayers or centralized operators, EIL is designed around on-chain contracts, preserving Ethereum’s core principles of self-custody, censorship resistance, privacy and verifiability.

Vision & Goals

Seamless Multichain UX

Users sign once; wallets figure out how to route the transaction across L2s.

CrossfChain Gas Abstraction

Users don’t need to hold gas on every chain. Instead, they can pay for gas with tokens from one chain, for all chains in the cross chain transaction

Trustless

• Communication is done solely on-chain. No reliance on opaque relayers or off-chain services. Users transact directly with the chain and liquidity providers never know users’ intentions in advance.
• Users' funds are never at risk. Transfer assets cross chain without relying on a third party cenralized service to release your funds and transact on your behalf.

On-chain Dispute Mechanism

Stake and dispute logic to penalize misbehavior by liquidity providers or malicious users.

Core Contracts

Here are the major contract components in the Ethereum Interop Layer protocol and their roles:

CrossChainPaymaster

The main singleton EIL contract deployed on every chain.

Acts as the Paymaster for cross-chain gas payments on the destination chain.

Users lock funds into this contract on the origin chain, specifying which liquidity providers will be accepted, and request a Voucher for the destination chain.

L1StakeManager

Manages the stake of XLPs on the Ethereum Mainnet.

Liquidity providers lock stake on L1 to back their cross-chain liquidity.

The stake is used for security in case of a dispute. If an XLP misbehaves, their stake can be slashed.

VoucherRequest and Voucher structs

Represents a user request and the correspondon obligation by an XLP to fulfill the cross-chain transaction on the destination chain.

When a user locks funds in the CrossChainPaymaster and requests a voucher,all allowed XLPs compete to issue the Voucher according to a fee schedule specified in the VoucherRequest in a reverse dutch auction model.

Dispute contracts

These contracts handle dispute resolution.

If a voucher is misused, or funds are not properly delivered, other actors can submit a dispute on-chain to the L1 and trigger slashing of stake.

How It Works: High-Level Flow

Here is a simplified sequence of how a cross-chain transaction works under EIL:

1. Wallet constructs multiple UserOps for every chain

The user’s wallet creates a set of UserOperation objects that together specify a cross-chain operation, i.e. "send 90 USDC from Arbitrum to Optimism", or even something more complex: calls, swaps, mints, etc.

2. Lock funds & request voucher
   When submitting the operation on the origin chain, the UserOp deposits funds into the CrossChainPaymaster, and creates a request for a voucher from eligible XLPs.

3. XLP issues vouchers

Registered XLPs on that chain see the request and compete to submit vouchers issuance.

4. User Operation executes

Once an XLP issues a voucher, the wallet, that listens to this event, attaches the voucher to the destination chain UserOp, and complete its execution. Funds are locked, the voucher is accepted, and the "cross-chain call" is effectively finalized on the destination chain.

5. Settlement or dispute (if needed)

   • If everything goes well, the transaction finalizes on the destination chain.
   • If there's a dispute (e.g., XLP doesn’t fulfill or misbehaves), anyone can raise a dispute on L2 origin and destination chains to L1, and the offending XLP’s stake will be slashed.

6. Redemption / withdrawal
   After successful execution, liquidity is reconciled, and XLPs can reclaim funds on the origin chain.

This gives users a near–instant, one-signature cross-chain experience, without trusting centralized bridges or relayers.

Trust Model & Security

• Self-custody: Users retain control; they sign all UserOps from their own wallet.
• No relayer trust: Liquidity providers (XLPs) never see users' private data — they only see the voucher requests.
• Economic security: XLPs must lock a stake on the L1. Dishonest behavior will lead to slashing via the L1 smart contract.
• On-chain dispute resolution: Built-in dispute mechanism to enforce correct behavior.

Getting Started

To work with this repo:

1. Clone

   git clone https://github.com/eth-infinitism/eil-contracts.git  
   cd eil-contracts

2. Install dependencies

yarn install

3. Compile

npx hardhat compile  
# or using forge:  
forge build

4. Test

npx hardhat test