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Integrate Embedded Wallets with the Polkadot Blockchain

While using the Embedded Wallets Web SDK (formerly Web3Auth) for a non-EVM chain like Polkadot, you can get the user's private key from the provider. Using this private key, you can use the corresponding libraries of the blockchain to make blockchain calls like getting the user's account, fetching balance, and sign & send transaction. We have highlighted a few methods here to get you started quickly.

note

The SDKs are now branded as MetaMask Embedded Wallet SDKs (formerly Web3Auth Plug and Play SDKs). Package names and APIs remain Web3Auth (for example, Web3Auth React SDK), and code snippets may reference web3auth identifiers.

Installation​

For Polkadot, we will use the libraries @polkadot/keyring and @polkadot/util-crypto to create the Polkadot address.

npm install --save @polkadot/keyring @polkadot/util-crypto

Initializing Provider​

Getting the chainConfig​

Get Account and KeyPair​

Once a user logs in, the Embedded Wallets SDK returns a provider. Since there isn't a native provider for Polkadot, we directly use the private key to make RPC calls.

Using the function, web3auth.provider.request({method: "private_key"}) from Web3Auth provider, the application can have access to the user's private key. However, we cannot use this key with Polkadot-specific signing functions, hence, we first derive the Polkadot Keyring using the Keyring class.

import { Keyring } from '@polkadot/api'
import { cryptoWaitReady } from '@polkadot/util-crypto'

/*
  Use code from the above Initializing Provider here
*/

// web3authProvider is web3auth.provider from above
const privateKey = await web3authProvider.request({ method: 'private_key' })

// cryptoWaitReady is required to initialize the Keyring
await cryptoWaitReady()
const keyring = new Keyring({ ss58Format: 42, type: 'sr25519' })
const keyPair = keyring.addFromUri('0x' + privateKey)
// keyPair.address is the account address.
const address = keyPair.address

Get Balance​

import { Keyring } from '@polkadot/api'
import { cryptoWaitReady } from '@polkadot/util-crypto'
import { ApiPromise, WsProvider } from '@polkadot/api'

/*
  Use code from the above Initializing Provider here
*/

// web3authProvider is web3auth.provider from above
const privateKey = await web3authProvider.request({ method: 'private_key' })

// cryptoWaitReady is required to initialize the Keyring
await cryptoWaitReady()
const keyring = new Keyring({ ss58Format: 42, type: 'sr25519' })
const keyPair = keyring.addFromUri('0x' + privateKey)

const provider = new WsProvider('wss://westend-rpc.polkadot.io') // testnet
// const provider = new WsProvider("wss://rpc.polkadot.io"); // Polkadot Relay Chain

// Create the API and wait until ready
const api = await ApiPromise.create({ provider })

// Retrieve the chain & node information information via rpc calls
const data = await api.query.system.account(keyPair.address)

// Balance
const balance = data.toHuman()

Send Transaction​

import { Keyring } from '@polkadot/api'
import { cryptoWaitReady } from '@polkadot/util-crypto'
import { ApiPromise, WsProvider } from '@polkadot/api'

/*
  Use code from the above Initializing Provider here
*/

// web3authProvider is web3auth.provider from above
const privateKey = await web3authProvider.request({ method: 'private_key' })

// cryptoWaitReady is required to initialize the Keyring
await cryptoWaitReady()
const keyring = new Keyring({ ss58Format: 42, type: 'sr25519' })
const keyPair = keyring.addFromUri('0x' + privateKey)

const provider = new WsProvider('wss://westend-rpc.polkadot.io') // testnet
// const provider = new WsProvider("wss://rpc.polkadot.io"); // Polkadot Relay Chain

// Create the API and wait until ready
const api = await ApiPromise.create({ provider })

// Transfer 12345 units to '5Gzhnn1MsDUjMi7S4cN41CfggEVzSyM58LkTYPFJY3wt7o3d'
const txHash = await api.tx.balances
  .transferKeepAlive('5Gzhnn1MsDUjMi7S4cN41CfggEVzSyM58LkTYPFJY3wt7o3d', 12345)
  .signAndSend(keyPair)

console.log('txHash', txHash.toHuman())
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