Fuel TS SDK

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Locking and Unlocking

Icon LinkLocking and Unlocking

The kinds of operations we can perform with a Wallet instance depend on whether or not we have access to the wallet's private key.

In order to differentiate between Wallet instances that know their private key and those that do not, we use the WalletUnlocked and WalletLocked types respectively.

Icon LinkWallet States

The WalletUnlocked type represents a wallet whose private key is known and stored internally in memory. A wallet must be of type WalletUnlocked in order to perform operations that involve signing messages or transactions .

The WalletLocked type represents a wallet whose private key is not known or stored in memory. Instead, WalletLocked only knows its public address. A WalletLocked cannot be used to sign transactions, however it may still perform a whole suite of useful operations including listing transactions, assets, querying balances, and so on.

Note that the WalletUnlocked type implements most methods available on the WalletLocked type. In other words, WalletUnlocked can be thought of as a thin wrapper around WalletLocked that provides greater access via its private key.

Icon LinkBasic Example

// #import { Wallet, WalletLocked, WalletUnlocked };
 
// use the `generate` helper to make an Unlocked Wallet
const myWallet: WalletUnlocked = Wallet.generate({
  provider,
});
 
// or use an Address to create a wallet
const someWallet: WalletLocked = Wallet.fromAddress(myWallet.address, provider);

Icon LinkOptional Provider

You can choose not to pass through a provider argument on Wallet construction:

import { Wallet, WalletUnlocked } from 'fuels';
 
// You can create a wallet, without a provider
let unlockedWallet: WalletUnlocked = Wallet.generate();
unlockedWallet = Wallet.fromPrivateKey(unlockedWallet.privateKey);
 
// All non-provider dependent methods are available
unlockedWallet.lock();
 
// All provider dependent methods will throw
await expect(() => unlockedWallet.getCoins()).rejects.toThrow(/Provider not set/);

Icon LinkTransitioning States

A WalletLocked instance can be unlocked by providing the private key:

const lockedWallet: WalletLocked = Wallet.fromAddress(myWallet.address, provider);
// unlock an existing wallet
let unlockedWallet: WalletUnlocked = lockedWallet.unlock(PRIVATE_KEY);
// or directly from a private key
unlockedWallet = Wallet.fromPrivateKey(PRIVATE_KEY, provider);

A WalletUnlocked instance can be locked using the lock method:

const newlyLockedWallet = unlockedWallet.lock();

Most wallet constructors that create or generate a new wallet are provided on the WalletUnlocked type. Consider locking the wallet with the lock method after the new private key has been handled in order to reduce the scope in which the wallet's private key is stored in memory.

Icon LinkDesign Guidelines

When designing APIs that accept a wallet as an input, we should think carefully about the kind of access that we require. API developers should aim to minimise their usage of WalletUnlocked in order to ensure private keys are stored in memory no longer than necessary to reduce the surface area for attacks and vulnerabilities in downstream libraries and applications.