Secure Transfer Bridge

Cross-network fund mobility is essential for active workspaces. SynArc integrates secure, direct bridge protocols to support bidirectional, 1:1 transfers of stable digital dollars (USDC) between Arc Testnet and other major networks, without the risks of intermediary wrapping contracts.

Bidirectional Transfer Flows

SynArc supports bridging in both directions:

Deposit (IN): Bridge USDC from Ethereum Sepolia, Base Sepolia, Avalanche Fuji, or Solana Devnet onto Arc Testnet to fund a project workspace, deposit into the Treasury, or back active campaigns.
Withdraw (OUT): Bridge USDC from Arc Testnet back to Ethereum Sepolia, Base Sepolia, Avalanche Fuji, or Solana Devnet to distribute assets to external participant vaults.

How Direct Transfers Work Under the Hood

Cross-Chain Transfer Protocol (CCTP) is a native utility by Circle that enables secure burn-and-mint transfers of USDC across blockchains. No liquidity pools or third-party wrappers are used.

#### The 4-Step Bridge Pipeline

01 - Burn USDC on Source: Initiate burn on source chain (e.g., Arc Testnet or Ethereum Sepolia).
02 - Circle Consensus Attestation: Poll Circle Sandbox Iris API for consensus validation.
03 - Attestation Signed & Received: Cryptographic proof generated and returned by Circle.
04 - Mint USDC on Destination: Submit message and attestation to complete mint on destination chain.

> 💡 Try It Yourself: Trigger a CCTP Transfer on the Bridge tab or run a rebalance on the Agent dashboard to see this pipeline execute live in real-time.

sequenceDiagram
    participant User as User Wallet
    participant Messenger as TokenMessenger (Source)
    participant Iris as Circle Iris Attestation API
    participant Transmitter as MessageTransmitter (Dest)

    User->>Messenger: 1. approve() & depositForBurn()
    Messenger-->>User: Emit MessageSent event (message bytes)
    Note over User,Iris: Wait for Circle consensus validation (~15-30s)
    User->>Iris: 2. Request attestation signature (messageHash)
    Iris-->>User: Returns completed attestation signature
    User->>Transmitter: 3. receiveMessage(message, attestation)
    Transmitter-->>User: Mints 1:1 native USDC directly to recipient

Step-by-Step Guides

1. Depositing USDC (IN) to Arc Testnet

To bridge USDC from an external chain into Arc Testnet:

Navigate to the Bridge tab on the dashboard sidebar.
Ensure the toggle is set to Deposit (IN).
Select your origin chain (e.g., *Ethereum Sepolia*, *Base Sepolia*, *Avalanche Fuji*).
Enter the amount of USDC you wish to deposit.
Click Initiate Cross-Chain Bridge:

Approve: Your wallet will prompt you to approve the origin TokenMessenger (0x8fe6b...) to spend your USDC.
Burn: A second transaction will submit the burn instruction.
Attestation: The SynArc interface polls Circle's Iris sandbox API for consensus proofs.
Mint: The app switches your wallet to Arc Testnet (chainId: 5042002) and submits the mint transaction to the Arc MessageTransmitter.

Your native USDC is now available on Arc Testnet.

2. Withdrawing USDC (OUT) from Arc Testnet

To withdraw your USDC reserves back to an external chain:

Navigate to the Bridge tab.
Switch the toggle to Withdraw (OUT).
Select your target destination chain.
Enter the amount of USDC you wish to withdraw.
Click Initiate Cross-Chain Bridge:

Approve: Approve the Arc TokenMessenger (0x8FE6B...) to spend your Arc USDC.
Burn: Submit the burn instruction on Arc Testnet.
Attestation: The app polls the Circle Iris API.
Mint: The app switches your wallet to the destination chain (e.g., Base Sepolia) and claims the minted native USDC.

Official CCTP Deployed Contracts

SynArc coordinates with the following verified Circle contract endpoints:

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