Permissionless Token bridging

Permissionless bridging is easy with anyCall. Anyone can deploy a working bridge for any tokens in minutes.

When users bridge, the tokens are burnt on the source chain and you use anyCall to pass a message cross-chain to mint the same amount of tokens on the destination chain.

The following instructions would be partnered with examples. We would showcase this with a permissionless bridge from fantom testnet to rinkeby.

1. Token Contract: Deploy tokens compatible with anyswaperc20 standards. Refer to the guide below:

How to develop under Anyswap ERC20 standards

Example:

	Fantom Testnet	Rinkeby
Erc20 address	https://testnet.ftmscan.com/address/0x8b38492ebb4f36564dd72e5583fa233a3fbf12cc#code	https://rinkeby.etherscan.io/address/0x8f9ad58819cb11036d5ff69d0e1a6392f9e9172a

2. Bridge Contract: Deploy your own bridge contract that uses anyCall to pass messages cross-chain.

Fork the following contract and constructor arguments should be anycall contract address and admin address.

multichain-smart-contracts/contracts/anycall/client-v6/AnyswapTokenAnycallClient.sol at main · anyswap/multichain-smart-contractsGitHub

Callproxy should be set to anycall contract address. This information can be found here:

How to integrate anyCall V6?

Example:

	Fantom Testnet	Rinkeby
Bridge Contract address	https://testnet.ftmscan.com/address/0xad4791B8813620185699035F7DEC3cbDb8e39e2d	https://rinkeby.etherscan.io/address/0xc29d6110f18b1d03c75e8756617e7d0a5f5f9d70#code

3. Set Minters for your token

Minting and burning rights need to be given on both the destination and source chain:

a. Bridge Contract: Your bridge contract will be burning and minting tokens in the bridge process.

The default anyerc20 implementation contains a timelock, you have to call applyMinter after timelock is finished.

Example:

	Fantom Testnet	Rinkeby
Give Minter to Bridge Contract	https://testnet.ftmscan.com/tx/0x9264cdd77d043711a32fc2ed393f6474151244952905750a24508b2b79034a3e	https://rinkeby.etherscan.io/tx/0x85f03d4875a8f9daf214a3b522c3af83c9b9ce3a09a4a4ac44210dd46b41d69e

4. Set Token peers and Client peers on your Bridge Contract

Client peers: setClientPeers(uint256[] _chainIds, address[] _peers) This stores information of the destination chain bridge contract address to issue anycall on the correct destination contracts.

Token peers: setTokenPeers(address srcToken, uint256[] chainIds, address[] dstTokens) This stores information of destination chain token address. This makes sure the right token is interacted.

Example:

	Fantom Testnet	Rinkeby
Set Client Peers	https://testnet.ftmscan.com/tx/0x817613572e8264f8a522a5461b959f45908e7f93387b6f086e1abadc9b29b2a4	https://rinkeby.etherscan.io/tx/0xc473a68d1e07b314a25a867a66ad70d20651dc19bbef0df2bb305e29a49222da
Set Token Peers	https://testnet.ftmscan.com/tx/0x41e4de809cf6619feb788adb920d384677223fb59cf71b1119c5df0cd3d6e510	https://rinkeby.etherscan.io/tx/0x3e89112a47a5f33db37cdb7ebe0e572fb5988da50ff0e7ab409b4be926da6391

4. Issue cross-chain bridge tx

This is an example of the bridge process in production. We are bridging from fantom testnet to rinkeby.

The fantom testnet tx is done with flags 2 as the argument and the tx was sent with some ftm as msg.value. This means we would cover the gas fee of destination chain execution on the source chain.

	Fantom Testnet	Rinkeby
Step 1: Swapout (Bridge out/Burn the tokens)	https://testnet.ftmscan.com/tx/0x2b392d8b8fe72ec119bbd5a172c091521d5b509ea7208f64bd65922a45f69b90
Step 2: AnyExec (Bridge In/Mint the tokens)		https://rinkeby.etherscan.io/tx/0x2368cf7fe5a9c3f0d4aec9bd129155c22565430d9dbb0d7757cfedec77cadf51

5 . User Interface

After you build out the permissionless bridge, you can host the frontend on your ui or apply to be included on our website. If you wish to be listed on our website, please contact our team through this email: [email protected].