Hierarchical deterministic (HD) wallets

Privy embedded wallets are hierarchical deterministic (HD) wallets. An HD wallet allows you to generate multiple Ethereum addresses and private keys from a shared source of entropy: the wallet seed (or equivalently, a BIP-39 mnemonic encoding the seed, known as a seed phrase).

In kind, Privy can be used to provision multiple embedded wallets for a single user. Read more below to learn how!

Read more about how HD wallets work.

HD wallets use a shared source of entropy to derive the wallet seed; this entropy is protected by the Privy cryptosystem.

Each wallet is generated from the seed and a unique path parameter, which has the format:

m / purpose' / coin_type' / account' / change / address_index

For Privy's embedded wallets, the path used for the i-th wallet is:

m/44'/60'/0'/0/i

where i is 0-indexed. An HD wallet is said to have an index of i if it is derived from the i-th path above. You can read more about these derivation paths here.

Creating multiple HD wallets

To create multiple Ethereum wallets for a user, use the create method from the useEmbeddedEthereumWallet hook:

import {useEmbeddedEthereumWallet} from '@privy-io/expo';

const {create} = useEmbeddedEthereumWallet();

As a parameter to create, pass an object containing a createAdditional boolean specifying if you would like to create an additional wallet, even if the user has an existing one.

Prop	Type	Description
createAdditional	boolean	If true, will allow the user to create a Ethereum wallet regardless if it is their first Ethereum wallet or an additional Ethereum wallet. If false, create will succeed only if the use is creating their first wallet. Defaults to false.

Once invoked, create will return a Promise that resolves to the newly created wallet, if it was successful. This method will reject with an error if:

• the user is not authenticated.
• the user already has an embedded Ethereum wallet and createAdditional was not set to true.
• if there is another error during wallet creation, such as the user exiting prematurely.

// Creating additional embedded wallets for the user
// You can also create the first wallet for the user using this syntax
await create({createAdditional: true});

Using multiple HD wallets

Once a user has one or more embedded wallets, the wallets are added to the wallets array returned by useEmbeddedEthereumWallet:

import {useEmbeddedEthereumWallet} from '@privy-io/expo';
...
const {wallets} = useEmbeddedEthereumWallet();

Refer to the requests section to learn how to interact with the wallets you create.

Getting a specific embedded wallet

To find a specific embedded wallet for the user, search the wallets array for a wallet with the address that matches your desired address:

const desiredAddress = 'insert-your-desired-wallet-address';
const {wallets} = useEmbeddedEthereumWallet();
const desiredWallet = wallets.find((wallet) => wallet.address === desiredAddress);

You can alternatively search the wallets array by your desired HD index:

// Replace this with your desired HD index
const desiredHdIndex = 0;
const {wallets} = useEmbeddedEthereumWallet();
const desiredWallet = wallets.find((wallet) => wallet.walletIndex === desiredHdIndex);