SKALE Chain to SKALE Chain ERC721 Transfer

As a SKALE chain Owner, there are two main steps to managing SKALE Chain to SKALE Chain (S2S) ERC721 transfer through IMA:

One-time setup to another SKALE Chain
Transferring ERC721 S2S

Once you have completed step 1 to setup ERC721 tokens with another chain, end-users can transfer ERC721 tokens between SKALE Chains.

Setup ERC721 S2S Transfers

The following one-time setup is required for SKALE Chains with a default access control policy (default settings are: whitelisting enabled, automatic deployment disabled). For more information on IMA access control, see here.

1. Enable Automatic Deploy

There are several limits to using automatic deployment. When using this method:

All token types support only basic token functionality. For example, special features such as ERC777 hooks and operators, fee-on-transfer, inflationary, etc., will not be mapped over. Be sure to review the token features supported by automatic deployment of each token type here: https://github.com/skalenetwork/IMA/tree/develop/proxy/contracts/schain/tokens. If you require any specialized features, please use the manual mapping process.
ERC20 token clones are based on OpenZeppelin’s library and use 18 decimals. See: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/d4d8d2ed9798cc3383912a23b5e8d5cb602f7d4b/contracts/token/ERC20/ERC20.sol#L87. If you require a different representation, then use the manual deployment process.

First, enable automatic deploy on the origin chain.

Only the AUTOMATIC_DEPLOYER_ROLE may enable or disable automatic deployment.

IMA-JS
Web3 JS

// import & init ima-js here

export async function enableAutomaticDeployERC20(ima) {
    let address = "YOUR_ADDRESS";
    let privateKey = "YOUR_PRIVATE_KEY";

    let txOpts = {
        address: address,
        privateKey: privateKey // remove privateKey from txOpts to use Metamask signing
    };

    await ima.schain.enableAutomaticDeploy("ERC20", txOpts);
}

// TODO

2. Connect the target SKALE chain

Add the target chain by using connectSchain within the TokenManagerLinker contract on the origin chain.

Only the REGISTRAR_ROLE may execute connectSchain.

IMA-JS
Web3 JS

// TODO

const Web3 = require('web3');
const Tx = require('ethereumjs-tx').Transaction;

let schainABIs = require("[YOUR_SKALE_CHAIN_ABIs]");
let privateKey = Buffer.from('[YOUR_PRIVATE_KEY]', 'hex')
let account = "[YOUR_ACCOUNT_ADDRESS]";
let schainEndpoint = "[YOUR_SKALE_CHAIN_ENDPOINT]";
let chainId = "ORIGIN_CHAIN_ID";
let targetSchainName = "TARGET_SKALE_CHAIN_NAME";

const tokenManagerLinkerAddress = schainABIs.token_manager_linker_address;
const tokenManagerLinkerABI = schainABIs.token_manager_linker_abi;

const web3 = new Web3(new Web3.providers.HttpProvider(schainEndpoint));

let contract = new web3.eth.Contract(
  tokenManagerLinkerABI, 
  tokenManagerLinkerAddress
);

/* 
 * Prepare connectSchain
 */
let connectSchain = contract.methods.connectSchain(targetSchainName)
  .encodeABI();  

//get nonce
web3.eth.getTransactionCount(account).then((nonce) => {
  //create raw transaction
  const rawTx = {
    chainId: chainId,
    nonce: "0x" + nonce.toString(16),
    from: account, 
    nonce: "0x" + nonce.toString(16),
    data : connectSchain,
    to: tokenManagerLinkerAddress,
    gasPrice: 100000000000,
    gas: 8000000
  }

  //sign transaction
  const tx = new Tx(rawTx);
  tx.sign(privateKey);

  //serialize transaction
  const serializedTx = tx.serialize();

  //send signed transaction
  web3.eth.sendSignedTransaction('0x' + serializedTx.toString('hex')).
    on('receipt', receipt => {
      //record receipt to console
      console.log(receipt);
   }).
    catch(console.error);
});

Get Started with S2S ERC721 Transfer

Be sure to follow any one-time setup and mapping steps described here before initiating S2S transfers.

1. S2S Transfer ERC721 From Origin

To send ERC721 tokens from a user’s wallet to another SKALE Chain, you will need to use the transferToSchainERC721 function within the TokenManagerERC721 IMA contract on the origin chain.

This method is called from the origin chain to move ERC721 tokens to a target chain.

The TokenManagerERC721 contract is predeployed on each SKALE Chain. To get the SKALE Chain ABIs, check out the current release page.

IMA-JS
Web3 JS

// todo

const Web3 = require("web3");
const Tx = require("ethereumjs-tx").Transaction;

let originABIs = "IMA_ABI_ON_ORIGIN";
let originERC721ABI = "ERC721_ABI_ON_ORIGIN";

let privateKey = Buffer.from("END_USER_PRIVATE_KEY", 'hex')
let address = "ADDRESS";

let origin = "ORIGIN_ENDPOINT";
let targetChainName = "TARGET_CHAIN_NAME";
let originChainId = "ORIGIN_CHAIN_ID";

const tokenManagerAddress = originABIs.token_manager_erc721_address;
const tokenManagerABI = originABIs.token_manager_erc721_abi;

const erc721ABI = originERC721ABI.erc721_abi;
const erc721Address = originERC721ABI.erc721_address;
const tokenId = "TOKEN_ID";

const web3ForOrigin = new Web3(origin);

let tokenManager = new web3ForOrigin.eth.Contract(
    tokenManagerABI,
    tokenManagerAddress
);

const customCommon = Common.forCustomChain(
    "mainnet", {
        name: "skale-network",
        chainId: originChainId
    },
    "istanbul"
);

let contractERC721 = new web3ForOrigin.eth.Contract(erc721ABI, erc721Address);

let approve = contractERC721.methods
    .approve(
        tokenManagerAddress,
        tokenId
    )
    .encodeABI();

let transfer = tokenManager.methods
    .transferToSchainERC721(
        targetChainName,
        erc721Address,
        tokenId
    )
    .encodeABI();

web3ForOrigin.eth.getTransactionCount(address).then(nonce => {
    //create raw transaction
    const rawTxApprove = {
        chainId: originChainId,
        from: address,
        nonce: "0x" + nonce.toString(16),
        data: approve,
        to: erc721Address,
        gas: 6500000,
        gasPrice: 100000000000
    };

    //sign transaction
    const txApprove = new Tx(rawTxApprove, {
        common: customCommon
    });
    txApprove.sign(privateKey);

    const serializedTxApprove = txApprove.serialize();

    //send signed transaction (approve)
    web3ForOrigin.eth
        .sendSignedTransaction("0x" + serializedTxApprove.toString("hex"))
        .on("receipt", receipt => {
            console.log(receipt);
            web3ForOrigin.eth
                .getTransactionCount(address)
                .then(nonce => {
                    const rawTxDeposit = {
                        chainId: originChainId,
                        from: address,
                        nonce: "0x" + nonce.toString(16),
                        data: transfer,
                        to: tokenManagerAddress,
                        gas: 6500000,
                        gasPrice: 100000000000
                    };

                    //sign transaction
                    const txDeposit = new Tx(rawTxDeposit, {
                        common: customCommon
                    });

                    txDeposit.sign(privateKey);

                    const serializedTxDeposit = txDeposit.serialize();

                    //send signed transaction (deposit)
                    web3ForOrigin.eth
                        .sendSignedTransaction("0x" + serializedTxDeposit
                            .toString("hex"))
                        .on("receipt", receipt => {
                            console.log(receipt);
                        })
                        .catch(console.error);
                });
        })
        .catch(console.error);
});

2. Exit from SKALE Chain

To exit ERC721 tokens back to the origin chain, you will need to use the transferToSchainERC721 function within the TokenManagerERC721 IMA contract on the target chain, and specify the erc721Address on the origin chain.

The TokenManagerERC721 IMA contract is pre-deployed to your SKALE Chain. Please reach out to your account manager to receive the ABIs specific for your SKALE Chain.

IMA-JS
Web3 JS

// todo

const Web3 = require("web3");
const Tx = require("ethereumjs-tx").Transaction;

let targetABIs = "IMA_ABI_ON_TARGET";
let originERC721ABI = "ERC721_ABI_ON_ORIGIN";

let privateKey = Buffer.from("END_USER_PRIVATE_KEY", 'hex')
let address = "ADDRESS";

let target = "TARGET_ENDPOINT";
let originChainName = "ORIGIN_CHAIN_NAME";
let targetChainId = "TARGET_CHAIN_ID";

const tokenManagerAddress = targetABIs.token_manager_erc721_address;
const tokenManagerABI = targetABIs.token_manager_erc721_abi;

const erc721ABI = targetERC721ABI.erc721_abi;
const erc721TargetAddress = targetERC721ABI.erc721_address;
const erc721OriginAddress = originERC721ABI.erc721_address;
const tokenId = "TOKEN_ID";

const web3ForTarget = new Web3(target);

let tokenManager = new web3ForTarget.eth.Contract(
    tokenManagerABI,
    tokenManagerAddress
);

const customCommon = Common.forCustomChain(
    "mainnet", {
        name: "skale-network",
        chainId: targetChainId
    },
    "istanbul"
);

let contractERC721 = new web3ForTarget.eth.Contract(erc721ABI, erc721TargetAddress);

let approve = contractERC721.methods
    .approve(
        tokenManagerAddress,
        tokenId
    )
    .encodeABI();

let transfer = tokenManager.methods
    .transferToSchainERC721(
        originChainName,
        erc721OriginAddress,
        tokenId
    )
    .encodeABI();

    web3ForTarget.eth.getTransactionCount(address).then(nonce => {
    //create raw transaction
    const rawTxApprove = {
        chainId: targetChainId,
        from: address,
        nonce: "0x" + nonce.toString(16),
        data: approve,
        to: erc721Address,
        gas: 6500000,
        gasPrice: 100000000000
    };

    //sign transaction
    const txApprove = new Tx(rawTxApprove, {
        common: customCommon
    });
    txApprove.sign(privateKey);

    const serializedTxApprove = txApprove.serialize();

    //send signed transaction (approve)
    web3ForTarget.eth
        .sendSignedTransaction("0x" + serializedTxApprove.toString("hex"))
        .on("receipt", receipt => {
            console.log(receipt);
            web3ForTarget.eth
                .getTransactionCount(address)
                .then(nonce => {
                    const rawTxDeposit = {
                        chainId: targetChainId,
                        from: address,
                        nonce: "0x" + nonce.toString(16),
                        data: transfer,
                        to: tokenManagerAddress,
                        gas: 6500000,
                        gasPrice: 100000000000
                    };

                    //sign transaction
                    const txDeposit = new Tx(rawTxDeposit, {
                        common: customCommon
                    });

                    txDeposit.sign(privateKey);

                    const serializedTxDeposit = txDeposit.serialize();

                    //send signed transaction (deposit)
                    web3ForTarget.eth
                        .sendSignedTransaction("0x" + serializedTxDeposit
                            .toString("hex"))
                        .on("receipt", receipt => {
                            console.log(receipt);
                        })
                        .catch(console.error);
                });
        })
        .catch(console.error);
});

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