How to withdrw (childchain->rootchain)

Prerequisites

You'll need to have a successful bridge deployment to make any cross-chain transactions. If you haven't done so already, check out the local deployment guide here.

:::caution Key management and secure values When passing values to run transactions, it is important to keep sensitive values like private keys and API keys secure.

The sample commands provided in this guide use sample private keys for demonstration purposes only, in order to show the format and expected value of the parameter. It is important to note that hardcoding or directly passing private keys should never be done in a development or production environment.

Here are some options for securely storing and retrieving private keys ↓

- **Environment Variables:** You can store the private key as an environment variable and access it in your code. For example, in Linux, you can set an environment variable like this: `export PRIVATE_KEY="my_private_key"`. Then, in your code, you can retrieve the value of the environment variable using `os.Getenv("PRIVATE_KEY")`. - **Configuration Files:** You can store the private key in a configuration file and read it in your session. Be sure to keep the configuration file in a secure location and restrict access to it. - **Vaults and Key Management Systems:** If you are working with sensitive data, you might consider using a vault or key management system like a keystore to store your private keys. These systems provide additional layers of security and can help ensure that your private keys are kept safe.

Regardless of how a private key is stored and retrieved, it's important to keep it secure and not expose it unnecessarily.

:::

Withdrawing from the Rootchain

Withdrawing from the Childchain

For a detailed understanding of how bridging works, please refer to the sequence diagrams available here.

Withdraw

This command withdraws ERC-20 tokens from an Furtheon-powered chain to a rootchain.

Replace hex_encoded_txn_sender_private_key with the private key of the account that will be sending the transaction.
Replace receivers_addresses with a comma-separated list of Ethereum addresses that will receive the tokens.
Replace amounts with a comma-separated list of token amounts to be withdrawn for each receiver.
Replace child_erc20_predicate_address with the address of the ERC-20 predicate contract on the Furtheon-powered chain.
Replace child_erc20_token_address with the address of the ERC-20 token contract on the Furtheon-powered chain (optional, only required if the token is not a default ERC-20 token).
Replace child_chain_json_rpc_endpoint with the JSON-RPC endpoint of the Furtheon-powered chain.

 ./polygon-edge bridge withdraw-erc20 \
    --sender-key <hex_encoded_txn_sender_private_key> \
    --receivers <receivers_addresses> \
    --amounts <amounts> \
    --child-predicate <rchild_erc20_predicate_address> \
    --child-token <child_erc20_token_address> \
    --json-rpc <child_chain_json_rpc_endpoint>

Example ↓

- We're using a private key of `0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef`. - We're withdrawing tokens from two receiver addresses: `0x1111111111111111111111111111111111111111` and `0x2222222222222222222222222222222222222222`. - We're withdrawing `100` tokens from the first receiver and `200` tokens from the second receiver. - The address of the ERC-20 predicate contract on the Furtheon-powered chain is `0x3456789abcdef0123456789abcdef0123456789`. - The address of the ERC-20 token contract on the Furtheon-powered chain is `0x456789abcdef0123456789abcdef0123456789`. - The JSON-RPC endpoint for the Furtheon-powered chain is `http://json-rpc-endpoint.com:8545`.

./polygon-edge bridge withdraw-erc20 \
    --sender-key 0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef \
    --receivers 0x1111111111111111111111111111111111111111,0x2222222222222222222222222222222222222222 \
    --amounts 100,200 \
    --child-predicate 0x3456789abcdef0123456789abcdef0123456789 \
    --child-token 0x456789abcdef0123456789abcdef0123456789 \
    --json-rpc http://json-rpc-endpoint.com:8545

Exit

This command sends an exit transaction to the ExitHelper contract on the rootchain for a token that was deposited on the Furtheon-powered chain. It basically finalizes a withdrawal (initiated on the Furtheon-powered chain) and transfers assets to receiving address on a rootchain.

Replace hex_encoded_txn_sender_private_key with the private key of the account that will send the exit transaction.
Replace exit_helper_address with the address of the ExitHelper contract on the rootchain.
Replace exit_id with the ID of the exit event.
Replace root_chain_json_rpc_endpoint with the JSON-RPC endpoint of the rootchain.
Replace child_chain_json_rpc_endpoint with the JSON-RPC endpoint of the Furtheon-powered chain.

./polygon-edge bridge exit \
    --sender-key <hex_encoded_txn_sender_private_key> \
    --exit-helper <exit_helper_address> \
    --exit-id <exit_event_id> \
    --root-json-rpc <root_chain_json_rpc_endpoint> \
    --child-json-rpc <child_chain_json_rpc_endpoint>

Example ↓

In this example, we're sending an exit transaction on a test Furtheon instance: - We're using a private key of `0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef`. - The address of the `ExitHelper` contract on the rootchain is `0x123456789abcdef0123456789abcdef01234567`. - The ID of the exit event is `42`. - The JSON-RPC endpoint for the rootchain is `http://root-chain-json-rpc-endpoint.com:8545`, and the JSON-RPC endpoint for the Furtheon-powered chain is `http://json-rpc-endpoint.com:8545`.

./polygon-edge bridge exit \
    --sender-key 0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef \
    --exit-helper 0x123456789abcdef0123456789abcdef01234567 \
    --exit-id 42 \
    --root-json-rpc http://root-chain-json-rpc-endpoint.com:8545 \
    --child-json-rpc http://json-rpc-endpoint.com:8545

Withdraw

This command withdraws ERC-721 tokens from an Furtheon-powered chain to a rootchain.

Replace hex_encoded_sender_private_key with the private key of the account that will initiate the withdrawal.
Replace receivers_addresses with a comma-separated list of Ethereum addresses that will receive the withdrawn tokens on the rootchain.
Replace token_ids with a comma-separated list of token IDs to be withdrawn.
Replace child_predicate_address with the address of the predicate contract on the Furtheon-powered chain that holds the tokens being withdrawn.
Replace child_token_address with the address of the ERC-721 token contract on the Furtheon-powered chain that holds the tokens being withdrawn.
Replace child_chain_json_rpc_endpoint with the JSON-RPC endpoint of the Furtheon-powered chain.

./polygon-edge bridge withdraw-erc721 \
    --sender-key <hex_encoded_sender_private_key> \
    --receivers <receivers_addresses> \
    --token-ids <token_ids> \
    --child-predicate <child_predicate_address> \
    --child-token <child_token_address> \
    --jsonrpc <child_chain_json_rpc_endpoint>

Example ↓

In this example, we're withdrawing ERC-721 tokens from a test Furtheon instance: - We're using a private key of `0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef`. - We're withdrawing tokens with IDs `123` and `456`. - The address of the ERC-721 Furtheon-powered chain predicate contract is `0x23456789abcdef0123456789abcdef012345678`. - The address of the ERC-721 Furtheon-powered chain token contract is `0x3456789abcdef0123456789abcdef012345678`. - The JSON-RPC endpoint for the Furtheon-powered chain is `http://json-rpc-endpoint.com:8545`.

Exit

This command sends an exit transaction to the ExitHelper contract on the rootchain for a token that was deposited on the Furtheon-powered chain. It basically finalizes a withdrawal (initiated on the Furtheon-powered chain) and transfers assets to receiving address on a rootchain.

Replace hex_encoded_txn_sender_private_key with the private key of the account that will send the exit transaction.
Replace exit_helper_address with the address of the ExitHelper contract on the rootchain.
Replace exit_id with the ID of the exit event.
Replace root_chain_json_rpc_endpoint with the JSON-RPC endpoint of the rootchain.
Replace child_chain_json_rpc_endpoint with the JSON-RPC endpoint of the Furtheon-powered chain.

./polygon-edge bridge exit \
    --sender-key <hex_encoded_txn_sender_private_key> \
    --exit-helper <exit_helper_address> \
    --exit-id <exit_event_id> \
    --root-json-rpc <root_chain_json_rpc_endpoint> \
    --child-json-rpc <child_chain_json_rpc_endpoint>

Example ↓

In this example, we're sending an exit transaction on a test Furtheon instance: - We're using a private key of `0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef`. - The address of the `ExitHelper` contract on the rootchain is `0x123456789abcdef0123456789abcdef01234567`. - The ID of the exit event is `42`. - The JSON-RPC endpoint for the rootchain is `http://root-chain-json-rpc-endpoint.com:8545`, and the JSON-RPC endpoint for the Furtheon-powered chain is `http://json-rpc-endpoint.com:8545`.

./polygon-edge bridge exit \
    --sender-key 0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef \
    --exit-helper 0x123456789abcdef0123456789abcdef01234567 \
    --exit-id 42 \
    --root-json-rpc http://root-chain-json-rpc-endpoint.com:8545 \
    --child-json-rpc http://json-rpc-endpoint.com:8545

Withdraw

This command withdraws ERC-1155 tokens from the Furtheon-powered chain to the rootchain.

Replace hex_encoded_withdrawer_private_key with the private key of the account that will be withdrawing the tokens.
Replace receivers_addresses with a comma-separated list of Ethereum addresses that will receive the tokens.
Replace amounts with a comma-separated list of token amounts to be withdrawn for each receiver.
Replace token_ids with a comma-separated list of token IDs to be withdrawn.
Replace root_erc1155_token_address with the address of the ERC-1155 token contract on the rootchain.
Replace root_erc1155_predicate_address with the address of the ERC-1155 predicate contract on the rootchain.
Replace child_chain_json_rpc_endpoint with the JSON-RPC endpoint of the Furtheon-powered chain.

./polygon-edge bridge withdraw-erc1155 \
    --sender-key <hex_encoded_withdrawer_private_key> \
    --receivers <receivers_addresses> \
    --amounts <amounts> \
    --token-ids <token_ids> \
    --root-token <root_erc1155_token_address> \
    --root-predicate <root_erc1155_predicate_address> \
    --json-rpc <child_chain_json_rpc_endpoint>

Example ↓

In this example, we're withdrawing ERC-1155 tokens from a test Furtheon instance to the rootchain: - We're using a private key of `0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef`. - We're withdrawing tokens to a single receiver address: `0x1111111111111111111111111111111111111111`. - We're withdrawing `100` tokens with ID `1`. - The address of the ERC-1155 token contract on the rootchain is `0x123456789abcdef0123456789abcdef01234567`. - The address of the ERC-1155 predicate contract on the rootchain is `0x23456789abcdef0123456789abcdef012345678`. - The JSON-RPC endpoint for the Furtheon-powered chain is `http://json-rpc-endpoint.com:8545`.

./polygon-edge bridge withdraw-erc1155 \
    --sender-key 0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef \
    --receivers 0x1111111111111111111111111111111111111111 \
    --amounts 100 \
    --token-ids 1 \
    --root-token 0x123456789abcdef0123456789abcdef01234567 \
    --root-predicate 0x23456789abcdef0123456789abcdef012345678 \
    --json-rpc http://json-rpc-endpoint.com:8545

Exit

This command sends an exit transaction to the ExitHelper contract on the rootchain for a token that was deposited on the Furtheon-powered chain. It basically finalizes a withdrawal (initiated on the Furtheon-powered chain) and transfers assets to receiving address on a rootchain.

Replace hex_encoded_txn_sender_private_key with the private key of the account that will send the exit transaction.
Replace exit_helper_address with the address of the ExitHelper contract on the rootchain.
Replace exit_id with the ID of the exit event.
Replace root_chain_json_rpc_endpoint with the JSON-RPC endpoint of the rootchain.
Replace child_chain_json_rpc_endpoint with the JSON-RPC endpoint of the Furtheon-powered chain.

./polygon-edge bridge exit \
    --sender-key <hex_encoded_txn_sender_private_key> \
    --exit-helper <exit_helper_address> \
    --exit-id <exit_event_id> \
    --root-json-rpc <root_chain_json_rpc_endpoint> \
    --child-json-rpc <child_chain_json_rpc_endpoint>

Example ↓

In this example, we're sending an exit transaction on a test Furtheon instance: - We're using a private key of `0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef`. - The address of the `ExitHelper` contract on the rootchain is `0x123456789abcdef0123456789abcdef01234567`. - The ID of the exit event is `42`. - The JSON-RPC endpoint for the rootchain is `http://root-chain-json-rpc-endpoint.com:8545`, and the JSON-RPC endpoint for the Furtheon-powered chain is `http://json-rpc-endpoint.com:8545`.

./polygon-edge bridge exit \
    --sender-key 0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef \
    --exit-helper 0x123456789abcdef0123456789abcdef01234567 \
    --exit-id 42 \
    --root-json-rpc http://root-chain-json-rpc-endpoint.com:8545 \
    --child-json-rpc http://json-rpc-endpoint.com:8545