Bridging Casper to EVM

This guide walks you through bridging CEP-18 tokens from Casper Network to an EVM chain (Ethereum, Base, etc.).

Overview

When you bridge from Casper to EVM:

1. Burn: Your CEP-18 tokens are burned on Casper
2. Detection: Relayers detect the burn event
3. Attestation: Relayers verify and collect signatures
4. Unlock: ERC-20 tokens are unlocked to your Ethereum address

Why It's Faster

Casper → EVM transfers are significantly faster (~1-3 minutes) compared to EVM → Casper (~15-20 minutes) because:

• Casper has instant finality - No need to wait for multiple block confirmations
• Events are final as soon as the transaction is included in a block

Prerequisites

• Both wallets connected (see Connecting Wallets)
• CEP-18 tokens to bridge (bridged tokens from previous EVM → Casper transfers)
• CSPR for gas fees (~2.5 CSPR)

Step-by-Step Guide

Step 1: Select Casper as Source

1. Go to astralbeam.io
2. In the "From" section, select "Casper (Testnet)"
3. Click the swap arrows if EVM is currently selected as source
4. The "To" section will show the destination EVM network

Step 2: Select Token

1. Click "Select token" in the token input area
2. A modal will display your bridged CEP-18 tokens
3. Choose the token you want to bridge back (e.g., USDC, WETH)
4. Your CEP-18 token balance will be displayed

Step 3: Enter Amount

1. Enter the amount of tokens to bridge
2. Ensure you have sufficient balance
3. Note: You cannot bridge more than what's locked on the destination chain

Step 4: Review Transaction

1. Click "Review Bridged Transfer"
2. Review the transaction summary:

1. Verify your Ethereum address is correct

Step 5: Sign Burn Transaction

1. Click "Start Bridged Transfer"
2. Casper Wallet will open with the transaction details
3. Review the transaction:
   • Contract: TokenFactory
   • Method: burn
   • Amount: Your specified amount
   • Gas: ~2.5 CSPR
4. Click "Sign" in Casper Wallet
5. Wait for the transaction to be included in a block

Step 6: Wait for Attestations

After the burn transaction is confirmed:

1. The modal shows "Relayer Attestation" as active
2. The bridge's independent relayers detect your transaction
3. Each relayer verifies it and adds its approval
4. This typically takes 1-2 minutes

Step 7: Automatic Unlock

Once enough relayers have approved:

1. The unlock transaction is submitted to the destination chain automatically
2. Your ERC-20 tokens are transferred from the bridge to your address
3. The modal shows "Completed" status
4. View your tokens in MetaMask or on the block explorer

Transaction Progress Steps

Viewing Your Unlocked Tokens

In MetaMask

1. Open MetaMask
2. Ensure you're on the correct network (Sepolia)
3. Your token balance should update automatically
4. If not visible, add the token manually using its contract address

On Etherscan

1. Go to sepolia.etherscan.io
2. Search for your Ethereum address
3. Click "Token Holdings" or "ERC-20 Token Txns"
4. View your unlocked tokens

Tracking the Transaction

On the Transactions Page

1. Navigate to astralbeam.io/transactions
2. Find your transaction (most recent at top)
3. Click to expand and see detailed progress
4. View links to block explorers for each step

Transaction Statuses

Troubleshooting

Burn Transaction Failed

• Insufficient CSPR: Ensure you have ~2.5 CSPR for gas
• Insufficient tokens: Verify you have enough CEP-18 tokens
• Contract paused: Check if the bridge is temporarily paused

Attestation Taking Too Long

• Normal attestation time is 1-2 minutes
• If longer than 5 minutes, relayers may be processing many transactions
• Check the Transactions page for status updates

Unlock Not Received

1. Verify the unlock transaction was submitted (check Transactions page)
2. Check Etherscan for your address
3. Confirm you're on the correct network in MetaMask
4. Token may need to be added to MetaMask manually

"Insufficient Chain Liquidity" Error

This means more tokens are being burned than are locked on the target chain:

• Check per-chain liquidity using the API
• Try a smaller amount
• This can happen if liquidity was drained or not seeded

Gas and Fees

Example: Bridging 10 USDC Back

1. Connect Casper Wallet and MetaMask (Sepolia)
2. Select "Casper (Testnet)" as source
3. Select USDC from token list (your bridged CEP-18)
4. Enter "10" as amount
5. Review: 10 USDC (CEP-18) → 10 USDC (ERC-20)
6. Sign burn transaction in Casper Wallet (~2.5 CSPR gas)
7. Wait ~1-2 minutes for attestations
8. Receive 10 USDC (ERC-20) on Ethereum Sepolia

Native Token Bridging (WCSPR)

For native Casper tokens like WCSPR:

1. The process is similar but uses lock_native instead of burn
2. Wrapped ERC-20 tokens (wCSPR) are minted on the EVM chain
3. These wrapped tokens can be bridged back to unlock native CSPR tokens