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Guardians

Introduction​

The guardians feature adds an extra signing layer on top of transactions. This means that a guarded account (having the isGuarded flag set to true) will require a Guardian to sign the transaction before it can be executed.

Specifications of a guarded transaction​

The differences between a guarded transaction and a simple transaction are the following:

  • it contains the guardianAddress field
  • gasLimit has an extra 50000 gas added to it
  • options field needs to have the second least signinficant bit set to "1" (ex: options: 2)
  • version field needs to be set to 2

This is how a transaction can be formatted using @multiversx/sdk-core:

transaction.setGuardian(Address.fromBech32(activeGuardianAddress));
transaction.setVersion(TransactionVersion.withTxOptions());
transaction.setOptions(TransactionOptions.withOptions({
    guarded: true,
    hashSign: true // if available
}));

Signing the transaction​

Once these fields are set, the transaction must be signed by both Guardian (adding the guardianSignuature field) and UserSigner (adding the signature field). All signing providers (except Ledger) take care internally of formatting the transaction, as described above (excluding adding the extra gasLimit).

Signing the transaction with Ledger​

After formatting the transaction and applying the signature provided by the Ledger device, the transaction must be signed by the Guardian. This is done by sending the transaction (or transactions array) to the web wallet 2FA hook. The web wallet will then prompt the user to sign the transaction with the Guardian account, and respond with the signed transaction.

import { WalletProvider } from '@multiversx/sdk-web-wallet-provider';

const walletProvider = new WalletProvider('https://wallet.multiversx.com/dapp/init');
walletProvider.guardTransactions(transactions, {
    callbackUrl: encodeURIComponent('https://my-dapp.com'),
});

Once transactions are back from the web wallet, they can be retrieved as follows:

const signedTransactions = new WalletProvider('https://wallet.multiversx.com/dapp/init').getTransactionsFromWalletUrl();