> For the complete documentation index, see [llms.txt](https://docs.astralbeam.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.astralbeam.io/using-astralbeam/bridging-casper-to-evm.md).

# 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](/using-astralbeam/connecting-wallets.md))
* 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](https://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:

| Field     | Description                              |
| --------- | ---------------------------------------- |
| From      | Casper (Testnet)                         |
| To        | Ethereum (Sepolia) or selected EVM chain |
| Amount    | Token amount being bridged               |
| Recipient | Your Ethereum address (0x...)            |

3. 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. Relayers detect the burn event via Casper event API
3. Each relayer verifies the event and signs an attestation
4. Signatures are exchanged via P2P network
5. This typically takes 1-2 minutes

### Step 7: Automatic Unlock

Once M-of-N signatures are collected:

1. The leader relayer submits the unlock transaction to Ethereum
2. Your ERC-20 tokens are transferred from the locker to your address
3. The modal shows "Completed" status
4. View your tokens in MetaMask or Etherscan

## Transaction Progress Steps

| Step | Status              | Description                          |
| ---- | ------------------- | ------------------------------------ |
| 1    | Burn Tokens         | Burn CEP-18 on Casper                |
| 2    | Relayer Attestation | Relayers verify and sign (\~1-2 min) |
| 3    | Unlock on Ethereum  | ERC-20 tokens unlocked               |

## 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](https://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](https://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

| Status    | Meaning                                  |
| --------- | ---------------------------------------- |
| Pending   | Transaction in progress                  |
| Completed | Successfully bridged                     |
| Failed    | Transaction failed (see Troubleshooting) |

## 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

| Fee Type            | Amount     | Paid By  |
| ------------------- | ---------- | -------- |
| Casper Burn Gas     | \~2.5 CSPR | You      |
| Ethereum Unlock Gas | Variable   | Relayers |

## 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


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