Prerequisites for Aptos to EVM Tutorials

Before starting the Aptos to EVM tutorials, ensure you have:

Development Environment

Aptos CLI: Install the Aptos CLI by following the official installation guide.

Update Aptos CLI

If you have an existing installation of the Aptos CLI, make sure to update it to the latest version to avoid compatibility issues.
Node.js v20 or higher: You can use the nvm package to install and switch between Node.js versions. Once installed, verify the node version with:
```
node -v
```
Example output:
```
$ node -v
v22.15.0
```
Npm: For installing and managing dependencies.
Git: For cloning the repository.

Starter Kit Repository

Clone the CCIP Aptos Starter Kit:

git clone https://github.com/smartcontractkit/aptos-starter-kit.git

Navigate to the directory:
```
cd aptos-starter-kit
```
Install dependencies:
```
npm install
```

Understanding Named Addresses in the Manifest File (`Move.toml`)

The Move build system uses a manifest file, Move.toml, to define a package, its dependencies, and any named addresses it references. Named addresses are human-readable aliases for on-chain hexadecimal addresses, which makes the Move code cleaner, more readable, and easier to manage.

When you compile a Move package, the compiler replaces these aliases (e.g., @ccip_router) with their actual address values from the Move.toml file.

In the aptos-starter-kit, the example modules (like ccip_message_sender, ccip_message_receiver) need to interact with the core CCIP modules already deployed on the Aptos Testnet. The [addresses] section in their Move.toml files provides the necessary references.

Example Move.toml Address Block:

[addresses]
ccip = "0xc748085bd02022a9696dfa2058774f92a07401208bbd34cfd0c6d0ac0287ee45"
mcms = "0xbdf1b9aacb4e21bf6f255105831df0172e911d4748e488196fde10d2e2a4e32d"
mcms_register_entrypoints = "0x0"
ccip_onramp = "0xc748085bd02022a9696dfa2058774f92a07401208bbd34cfd0c6d0ac0287ee45"
ccip_router = "0xc748085bd02022a9696dfa2058774f92a07401208bbd34cfd0c6d0ac0287ee45"

Here is a breakdown of what each named address represents:

ccip: This is the main Object address under which the core CCIP packages and their modules (like fee_quoter, rmn_remote, token_admin_registry, etc.) are published.
ccip_router & ccip_onramp: These aliases also point to the main CCIP Object address. This is because the router and onramp modules are part of the packages published under that single, unified Object. The aliases are defined for clarity and consistency in the Move code's use statements.
mcms: This is the address of the on-chain ManyChainMultiSig (MCMS) module, which is responsible for handling governance and administrative actions for the CCIP protocol through a secure, time-locked implementation process.
mcms_register_entrypoints: This is a special value used as a compile-time flag. By setting it to 0x0, the module is compiled in a way that bypasses the logic for registering with the MCMS system. This is useful for certain testing or deployment scenarios where the MCMS module is not relevant.

By defining these addresses in the Move.toml file, the example modules can interact with the core CCIP protocol without hardcoding long addresses, making the code portable and easier to update for different networks.

Wallets

Aptos Account: You'll need an Aptos account. If you don't have one, create it with:
```
aptos init --network testnet
```
This command will guide you through creating a new account for Testnet and will save the credentials in a .aptos/config.yaml file. This also configures your Aptos CLI to use Testnet.
Note

If you want to use your existing account from Petra Wallet, you can export your account's private key, copy it, and use it in the following command:
```
aptos init --private-key <YOUR_PRIVATE_KEY> --network testnet
```
This command configures your Aptos CLI to use your existing account on Testnet and saves the credentials in a .aptos/config.yaml file.
Verify your current configuration with:
```
aptos config show-profiles
```
This should show your default profile configured for Testnet, with the network set to Testnet.

Example output:
```
$ aptos config show-profiles

{
  "Result": {
    "default": {
      "network": "Testnet",
      "has_private_key": true,
      "public_key": "ed25519-pub-0x2ecdd2d7bc0cbfe2e44c219ef9a9fddc986b384f4a01fb5d821cf0dab5d2fbae",
      "account": "d0e227835c33932721d54ae401cfaae753c295024fe454aa029b5e2782d2fad4",
      "rest_url": "https://fullnode.testnet.aptoslabs.com"
    }
  }
}
```
EVM Wallet Address: You'll need an EVM-compatible wallet address to receive tokens on the destination chain (Ethereum Sepolia). You only need the address itself, not the private key, as you are only sending to this address.

Environment Configuration (`.env` file)

The starter kit uses a .env file to manage sensitive information like private keys and RPC URLs. Create a new file named .env in the root of the aptos-starter-kit directory by copying the example file:

cp .env.example .env

Next, open the .env file and fill in the following values:

PRIVATE_KEY_HEX: The private key of your source wallet (EOA) on Aptos Testnet from which you're sending CCIP-BnM tokens. You can find this in the .aptos/config.yaml file created by the aptos init --network testnet command, as shown in the Wallets section above.
ETHEREUM_SEPOLIA_RPC_URL: The RPC endpoint for the Ethereum Sepolia testnet. This is required by the verification script (aptos2evm/checkMsgExecutionStateOnAptos.ts) to read the ExecutionStateChanged event from the CCIP OffRamp on Ethereum Sepolia. You can obtain an RPC URL by signing up for a personal endpoint from Alchemy, Infura, or another node provider service.

Example .env file:

PRIVATE_KEY_HEX=<YOUR_APTOS_PRIVATE_KEY_HEX>
ETHEREUM_SEPOLIA_RPC_URL=<RPC_URL_FOR_ETHEREUM_SEPOLIA>

Native Tokens for Transaction Fees

APT tokens are used for Aptos transaction fees. For these tutorials, we will also use APT to pay for CCIP fees.

Obtain APT on Testnet using the faucet:

You can use the official Aptos Testnet Faucet to get APT tokens. Simply enter your Aptos account address and click on Mint to request tokens.

Check your account balance:

aptos account balance

Example output:

$ aptos account balance

{
  "Result": [
    {
      "asset_type": "coin",
      "coin_type": "0x1::aptos_coin::AptosCoin",
      "balance": 100000000
    }
  ]
}

Obtaining Testnet Tokens

BnM Tokens on Aptos

To complete the cross-chain token transfer examples, you'll need BnM tokens. To obtain CCIP-BnM tokens on Aptos Testnet, run the faucets/aptos/dripCCIPBnMToken.ts script included in the starter kit.

Run the following command in your terminal:

npx ts-node scripts/faucets/aptos/dripCCIPBnMToken.ts --to <YOUR_APTOS_WALLET_ADDRESS>

The output looks like this:

1 CCIP-BnM token is minted to 0xd0e227835c33932721d54ae401cfaae753c295024fe454aa029b5e2782d2fad4 successfully.
Please check the transaction at https://explorer.aptoslabs.com/txn/0x7e5d5bae918c97cb086c72023012da2a8a230c91155f8ff697eb29001f606e55?network=testnet

Prerequisites for Aptos to EVM Tutorials

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