Bridge Tokens Between Ethereum and XRPL

Attention

Don't use any funds from a mainnet wallet to perform the actions in this tutorial. The steps outlined are for a testnet deployment, so any funds transferred from mainnet may be lost. Additionally:

Gas payments aren't currently supported. You don't need to call AxelarGasService on Ethereum Sepolia to refund our relayer since it's running "pro bono".
The bridge doesn't charge any fees currently.
The IAxelarGateway interface and AxelarExecutable smart contracts used in this tutorial are different from the ones currently deployed by Axelar. Instructions you find elsewhere likely won't be compatible with this testnet deployment.
Only one validator is used to secure this testnet bridge.
Only one relayer is active.

This tutorial describes how to transfer tokens between Ethereum Sepolia and the XRPL Testnet.

Prerequisites

Foundry
XRPL.js Library
An RPC provider, such as Alchemy or Infura, with the SEPOLIA_RPC_URL environment variable set to a working Sepolia RPC URL.
Funded wallets on both chains.
- ETH Sepolia Faucet: alchemy.com/faucets/ethereum-sepolia
- XRPL Testnet Faucet: faucet.tequ.dev

Bridge ETH

ETH from Ethereum to XRPL

Create a trust line on XRPL testnet between the Axelar multisig account and the destination account, using the TrustSet transaction.

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{
    "TransactionType": "TrustSet",
    "Account": user.address, // the XRPL address of the ETH transfer recipient
    "LimitAmount": {
        "currency": "ETH",
        "issuer": "rfEf91bLxrTVC76vw1W3Ur8Jk4Lwujskmb",
        "value": "10000000000",
    },
    ...
},

Wrap ETH on Ethereum Sepolia . You can do this using the Foundry cast command, or directly on Etherscan.
- Using Foundry's cast command:
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```
WETH=0x7b79995e5f793a07bc00c21412e50ecae098e7f9
cast send $WETH "deposit()" --value 0.1ether --private-key $PRIVATE_KEY --rpc-url $SEPOLIA_RPC_URL
```
- Using Etherescan , select Connect to Web3 to connect your wallet. Expand the deposit dropdown and type the amount of ETH you want to bridge. Click Write to perform the transaction.
Approve the AxelarGateway contract to spend your WETH on Ethereum Sepolia :
- Using Foundry's cast command:
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```
WETH=0x7b79995e5f793a07bc00c21412e50ecae098e7f9
AXELAR_GATEWAY=0xAABdd46ba1B3147d0Cf6aCc9605a74fE8668fC74
cast send $WETH "approve(address guy, uint256 amount)" $AXELAR_GATEWAY $(cast to-wei 0.1) --private-key $PRIVATE_KEY --rpc-url $SEPOLIA_RPC_URL
```
- Using Etherescan , select Connect to Web3 to connect your wallet. Expand the approve dropdown, enter AxelarGateway 's address ( 0x832B2dfe8a225550C144626111660f61B8690efD ), and the amount of ETH to bridge under deposit . Click Write to perform the transcation.

On Ethereum Sepolia, call AxelarGateway.sendToken() to bridge your WETH.

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AXELAR_GATEWAY=0xAABdd46ba1B3147d0Cf6aCc9605a74fE8668fC74
XRPL_DESTINATION= # your XRPL recipient address
cast send $AXELAR_GATEWAY "sendToken(string destinationChain, string destinationAddress, string symbol, uint256 amount)" "xrpl" $XRPL_DESTINATION "WETH" $(cast to-wei 0.1) --private-key $PRIVATE_KEY --rpc-url $SEPOLIA_RPC_URL

The destination address should receive the bridged ETH in a few minutes. You can check for a successful transaction on the XRPL Testnet explorer .

Wrapped ETH from XRPL to Ethereum

Deposit ETH into the XRPL multisig account, using a Payment transaction.

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{
    TransactionType: "Payment",
    Account: user.address, // The user initiating the transfer
    Amount: {
        currency: "ETH",
        value: "0.001", // = 10^15 wei - the amount of ETH you want to bridge, in ETH
        issuer: "rfEf91bLxrTVC76vw1W3Ur8Jk4Lwujskmb",
    },
    Destination: "rfEf91bLxrTVC76vw1W3Ur8Jk4Lwujskmb", // Axelar's XRPL multisig account
    Memos: [
        {
            Memo: {
                MemoData: "605459C28E6bE7B31B8b622FD29C82B3059dB1C6", // your ETH recipient address, without the 0x prefix
                MemoType: "64657374696E6174696F6E5F61646472657373", // hex("destination_address")
            },
        },
        {
            Memo: {
                MemoData: "657468657265756D", // hex("ethereum")
                MemoType: "64657374696E6174696F6E5F636861696E", // hex("destination_chain")
            },
        },
        {
            Memo: {
                MemoData: "0000000000000000000000000000000000000000000000000000000000000000", // bytes32(0) indicates pure token transfer, without GMP
                MemoType: "7061796C6F61645F68617368", // hex("payload_hash")
            },
        },
    ],
    ...
}

Within a few minutes, the destination_address should receive the bridged ETH on Ethereum Sepolia , as WETH. You can check for the transaction on the Ethereum Sepolia explorer .

Bridge XRP

Bridge ETH

XRP from XRPL to Ethereum

Deposit XRP into the XRPL multisig account, using a Payment transaction.

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{
    TransactionType: "Payment",
    Account: user.address, // The user initiating the transfer
    Amount: "1000000", // = 1 XRP - the amount of XRP you want to bridge, in drops
    Destination: "rfEf91bLxrTVC76vw1W3Ur8Jk4Lwujskmb", // Axelar's XRPL multisig account
    Memos: [
        {
            Memo: {
                MemoData: "605459C28E6bE7B31B8b622FD29C82B3059dB1C6", // your ETH recipient address, without the 0x prefix
                MemoType: "64657374696E6174696F6E5F61646472657373", // hex("destination_address")
            },
        },
        {
            Memo: {
                MemoData: "657468657265756D", // hex("ethereum")
                MemoType: "64657374696E6174696F6E5F636861696E", // hex("destination_chain")
            },
        },
        {
            Memo: {
                MemoData: "0000000000000000000000000000000000000000000000000000000000000000", // bytes32(0) indicates pure token transfer, without GMP
                MemoType: "7061796C6F61645F68617368", // hex("payload_hash")
            },
        },
    ],
    ...
}

Within a few minutes, the destination_address should receive the bridged XRP on Ethereum Sepolia, as Axelar-wrapped XRP (axlXRP). You can check for the transaction on the Ethereum Sepolia explorer .

Wrapped XRP (axlXRP) from Ethereum to XRPL

Approve the AxelarGateway contract to spend your axlXRP on Ethereum Sepolia :
- Using Foundry's cast command:
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```
AXL_XRP=0x40d5ed73982468499ecfa9c8cc0abb63ff13a409
AXELAR_GATEWAY=0xAABdd46ba1B3147d0Cf6aCc9605a74fE8668fC74
cast send $AXL_XRP "approve(address guy, uint256 amount)" $AXELAR_GATEWAY 1000000 --private-key $PRIVATE_KEY --rpc-url $SEPOLIA_RPC_URL
```
- Using Etherescan , select Connect to Web3 to connect your wallet. Expand the approve dropdown, enter the AxelarGateway 's address ( 0x832B2dfe8a225550C144626111660f61B8690efD ) and the amount of axlXRP to bridge under deposit . Click Write to perform the transcation.

On Ethereum Sepolia , call AxelarGateway.sendToken() to bridge your axlXRP.

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AXELAR_GATEWAY=0xAABdd46ba1B3147d0Cf6aCc9605a74fE8668fC74
XRPL_DESTINATION= # your XRPL recipient address
cast send $AXELAR_GATEWAY "sendToken(string destinationChain, string destinationAddress, string symbol, uint256 amount)" "xrpl" $XRPL_DESTINATION "axlXRP" 1000000 --private-key $PRIVATE_KEY --rpc-url $SEPOLIA_RPC_URL

Within a few minutes, your destination address should receive the XRP. You can check for the transaction on the XRPL Testnet explorer .