Crosschain Treasury Overview
The Crosschain Treasury enables secure asset transfers between EVVM and external blockchains using interoperability protocols.
Architecture
Two coordinated stations communicate through cross-chain protocols:
Host Chain Station
- Operates on EVVM's blockchain
- Handles withdrawals from EVVM to external chains
- Receives Fisher bridge deposits from external chains
- Integrates with EVVM core contract
External Chain Station
- Deployed on external blockchains
- Handles deposits from users to EVVM
- Receives Fisher bridge withdrawals from EVVM
- Manages real asset custody (ERC20 and native coins)
Supported Protocols
| Protocol | ID | Description |
|---|---|---|
| Hyperlane | 0x01 | Modular interoperability framework |
| LayerZero | 0x02 | Omnichain protocol |
| Axelar | 0x03 | Decentralized cross-chain network |
Fisher Bridge System
Gasless cross-chain transactions:
- Gasless Operations: No native tokens needed for gas on destination chains
- EIP-191 Signatures: User authorization via signed messages
- Priority Fees: Economic incentives for Fisher executors
- Nonce-Based Security: Replay attack prevention
When to Use
Ideal for:
- EVVM on different blockchain than user assets
- Multi-chain support
- Gasless transaction requirements
Available Documentation
Host Chain Station
- withdraw: Withdraw to external chains
- fisherBridgeReceive: Receive gasless deposits
- fisherBridgeSend: Process gasless withdrawals
- Admin Functions: System management
External Chain Station
- depositERC20: Deposit tokens to EVVM
- depositCoin: Deposit native coins to EVVM
- fisherBridgeReceive: Receive gasless withdrawals
- fisherBridgeSendERC20: Process gasless ERC20 transfers
- fisherBridgeSendCoin: Process gasless coin transfers
- Admin Functions: System configuration
Security Considerations
- Principal Token Protection: Principal token (MATE) withdrawals blocked via
PrincipalTokenIsNotWithdrawableerror - Cross-Chain Authorization: All messages require sender and chain ID validation
- Fisher Bridge Signatures: EIP-191 compliant signatures with structured message format
- Nonce-Based Protection: Sequential nonce tracking prevents replay attacks
- Time-Delayed Governance: 1-day delays for admin and Fisher executor changes
- Access Control:
onlyAdminandonlyFisherExecutormodifiers restrict critical functions - Protocol Validation: Chain-specific authorization for Hyperlane, LayerZero, and Axelar
- Balance Verification: Insufficient balance checks with
InsufficientBalanceerror protection
Gas Management
Each protocol requires different gas payment mechanisms:
- Hyperlane: Native tokens paid to mailbox contract
- LayerZero: Estimated fees through LayerZero endpoint
- Axelar: Gas service payments for cross-chain execution
Users must provide sufficient native tokens to cover cross-chain transaction costs when initiating transfers.