Smart Contract Reference

This section documents the smart contracts that power AstralBeam on both EVM chains and Casper Network.

Contract Overview

flowchart TB
    subgraph EVM[EVM Chains Solidity]
        Locker[MultiSigERC20Locker Lock/Unlock ERC-20]
        Wrapped[WrappedToken wCSPR, etc.]
    end

    subgraph Casper[Casper Network Rust]
        EthClient[EthClient Store EVM Block Headers]
        TokenFactory[TokenFactory Mint/Burn CEP-18]
        CEP18[CEP-18 Tokens Wrapped ERC-20]
    end

    Locker <--> TokenFactory
    Locker --> Wrapped
    TokenFactory --> CEP18
    EthClient --> TokenFactory

EVM Contracts

MultiSigERC20Locker

The primary bridge contract on EVM chains. Handles:

• Locking ERC-20 tokens for bridging to Casper
• Releasing ERC-20 tokens and minting wrapped tokens for transfers from Casper: through the ERC-7786 gateway on exposure-control lockers, with M-of-N signed unlock and mintWrapped on deployed V17 lockers
• Managing wrapped Casper-native tokens (e.g. wCSPR and sCSPR)
• Fee collection for bridge operations

Key Functions:

ERC-7786 gateway (in development)

AstralBeamERC7786Gateway is the EVM end of the ERC-7786 message transport that the mainnet exposure controls use. It is not deployed. It sends messages by emitting MessageSent, and delivers incoming messages only with a threshold of signatures from the locker's relayer set. Cross-chain addresses use ERC-7930, with Casper chain type 0x0004.

Casper Contracts

EthClient

EVM block header storage on Casper. Provides:

• Per-chain block header storage
• MPT proof verification
• M-of-N signature verification for submissions

Key Functions:

TokenFactory

CEP-18 token management on Casper. Handles:

• Minting wrapped tokens from EVM locks
• Burning tokens for unlock on EVM
• Native CSPR bridging support
• Per-chain token mappings

Key Functions:

ERC-7786 gateway (in development)

Erc7786Gateway is the Casper end of the ERC-7786 message transport. It is not deployed. It sends messages to EVM chains by emitting MessageSent, and delivers messages from EVM chains only with a threshold of signatures from EthClient's relayer set and a source block EthClient has anchored.

Deployed Addresses

Public testnet

These addresses belong to testnet.astralbeam.io and https://api.testnet.astralbeam.io. They are not interchangeable with development deployments.

All four chains use a deterministic proxy address; signatures remain bound to their chain ID. Arbitrum Sepolia and BSC Testnet are not active routes. Mainnet is not available in this public-testnet deployment.

Casper package hashes identify upgradeable packages, not a particular contract version. Resolve the current contract version before using version-specific APIs. Token addresses are listed separately in Supported Tokens.

Contract Interaction Patterns

Lock and Mint (EVM → Casper)

// 1. User approves tokens
await (await erc20.approve(lockerAddress, amount)).wait();

// 2. Read the current fee after approval, then lock tokens
const bridgeFee = await locker.bridgeFee();
const tx = await locker.lock(
    tokenAddress,
    amount,
    0, // Account hash recipient (not a public key)
    casperRecipientBytes32,
    { value: bridgeFee }
);

// 3. Relayers detect Locked event
// 4. Relayers submit to TokenFactory on Casper
// 5. User receives CEP-18 tokens

Burn and Unlock (Casper → EVM)

// 1. User burns CEP-18 tokens on Casper
let tx = token_factory.burn(
    cep18_token,
    amount,
    evm_recipient,
    destination_chain_id
);

// 2. Relayers detect BurnEvent
// 3. Relayers submit unlock to EVM
// 4. User receives ERC-20 tokens

Security Features

All contracts implement:

Upgradeability

Development Resources

Source Code

• EVM Contracts: /contracts/eth/
• Casper Contracts: /contracts/casper/

Build & Test

EVM (Foundry):

cd contracts/eth
forge build
forge test

Casper (Odra):

cd contracts/casper
cargo odra build
cargo odra test

ABI Files

EVM contract ABIs are available at:

• /contracts/eth/out/MultiSigERC20Locker.sol/