Demo

github.com/hedera-dev/hedera-code-snippets/blob/main/multisig-account

Code Walkthrough

    // generate keys
    const edKey = PrivateKey.generateED25519();
    const ecKey = PrivateKey.generateECDSA();

    // create a `ThresholdKey` that represents a 1 of 2 multisig threshold
    const multisigPublicKeys = [edKey.publicKey, ecKey.publicKey];
    const multisigKeyList = new KeyList(multisigPublicKeys, 1);

    // Update account to use this `KeyList`, via an `AccountUpdateTransaction`.
    // This replaces the single signature with a the 1 of 2 multisig
    const makeMultisigTx = new AccountUpdateTransaction()
        .setAccountId(multisigAccountId)
        .setKey(multisigKeyList)
        .freezeWith(client);
    const makeMultisigTxSignedByOneKey = await makeMultisigTx.sign(edKey);
    const makeMultisigTxSubmitted = await makeMultisigTxSignedByOneKey.execute(client);

    // Sign a `TransferTransaction` using the ECDSA key only,
    // then attempt to execute it
    const transfer1of2EcTx = new TransferTransaction()
        .addHbarTransfer(multisigAccountId, new Hbar(-34))
        .addHbarTransfer(operatorId, new Hbar(34))
        .freezeWith(client);
    const transfer1of2EcTxSigned = await transfer1of2EcTx.sign(ecKey);
    const transfer1of2EcTxSubmitted = await transfer1of2EcTxSigned.execute(client);

Demo

github.com/hedera-dev/hedera-code-snippets/blob/main/multisig-sc-account

Code Walkthrough

// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;
import "./IHederaTokenService.sol";
contract Account {
    IHederaTokenService hederaTokenService;

    constructor() {
        hederaTokenService = IHederaTokenService(address(0x0167));
    }

    function performPrecompileOperation(
        address token,
        address sender,
        address recipient,
        int64 amount
    ) external {
        int64 responseCode = hederaTokenService.transferToken(
            token, sender, recipient, amount);
        // HederaResponseCodes.SUCCESS = 22
        require(responseCode == 22, "HTS transfer error");
    }
}

    // Obtain the ID of the deployed smart contract
    const scId = scDeployTxRecord.receipt.contractId;
    console.log('scId', scId.toString());

    // Generate a new ECDSA key
    const ecKey = PrivateKey.generateECDSA();

    // Create a `ThresholdKey` that represents a 1 of 2 multisig threshold
    // where one of the keys is the smart contract ID, and the other is the ECDSA key
    const multisigPublicKeys = [scId, ecKey.publicKey];
    const multisigKeyList = new KeyList(multisigPublicKeys, 1);

    // Update account to use this `KeyList`, via an `AccountUpdateTransaction`.
    // This replaces the single signature with a the 1 of 2 multisig
    const makeMultisigTx = new AccountUpdateTransaction()
        .setAccountId(multisigAccountId)
        .setKey(multisigKeyList)
        .freezeWith(client);
    const makeMultisigTxSignedByAllKeys = await makeMultisigTx.sign(ecKey);
    const makeMultisigTxSubmitted = await makeMultisigTxSignedByAllKeys.execute(client);

    // Invoke `Account.performPrecompileOperation` function on the smart contract whose ID is
    // of the `KeyList` of the multisig account
    const scPerformPrecompileTx = new ContractExecuteTransaction()
        .setContractId(scId)
        .setGas(400_000)
        .setFunction(
            'performPrecompileOperation',
            new ContractFunctionParameters()
                .addAddress(toLongZeroEvmAddress(htsFtId))
                .addAddress(multisigAccountEvmAddress.toString())
                .addAddress(toLongZeroEvmAddress(operatorId))
                .addInt64(23),
        )
        .freezeWith(client);
    // NOTE that this transaction is intentionally **unsigned**.
    // This is to verify that the smart contract is also part of `KeyList` of the multisig account
    // does indeed fulfil its role in being able to authenticate the precompile transaction in lieu of a signature.
    const scPerformPrecompileTxSubmitted = await scPerformPrecompileTx.execute(client);

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