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You can use any authentication provider with the Polybase network. You simply need to provide a signer function to the Polybase client. Signing a request populates the ctx.publicKey variable inside your collection code, allowing you to write code that restricts who can read or write to a record. This can either be done when instantiating the client, using the signer configuration property: 
import { Polybase } from '@polybase/client'
import { ethPersonalSign } from '@polybase/eth'

const db = new Polybase({
  signer: (data) => {
    return {
      h: 'eth-personal-sign',
      sig: ethPersonalSign(wallet.privateKey()), data)
    }
  })
})
Or later by passing a function to the signer method: 
import { Polybase } from '@polybase/client'
import { ethPersonalSign } from '@polybase/eth'

const db = new Polybase()

db.signer((data) => {
  return {
    h: 'eth-personal-sign',
    sig: ethPersonalSign(wallet.privateKey()), data)
  }
})

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Polybase Auth

To make authentication easier, Polybase provides an authentication library that allows users to sign in to your app using web3 wallets or email. The library hides the complexity of the users chosen authentication method, providing a single API for you to sign requests regardless of the method they use to login.

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Install Polybase Auth

From Package Manager: 
npm install @polybase/auth

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Initialize

You should only run the new Auth class once, and then pass it to your app. 
import { Auth } from '@polybase/auth'

const auth = new Auth()

function App () {
  ...
}

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Next.js

Next.js runs your code both server side and client side. When running server side Next.js has no document so Auth will fail to load. Auth doesn’t make sense server side, so your code should handle this scenario by skipping any auth code. Before calling auth functions (e.g. auth.signIn()), you will need to check that auth is defined. 
const auth = typeof window !== "undefined" ? new Auth() : null;

function App () {
  const signIn = () => {
      auth?.signIn()
  }
}

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Sign in

import { Auth } from '@polybase/auth'

const auth = new Auth()

// Show the login modal (if not logged in), and wait for a response
const authState = await auth.signIn()
The authState for email login would be: 
{
  type: "email",
  email: "[email protected]",
  userId: "0xf998db2f1e53a00e9c59330b307cfcc03425b994d417a93c508def6d46ee12d8",
  publicKey: "0xf998db2f1e53a00e9c59330b307cfcc03425b994d417a93c508def6d46ee12d893c508def6d46ee12d8"
}
The authState for Metamask login would be: 
{
  type: "metamask",
  // userId is the ethereum address
  userId: "0xf998db2f1e53a00e9c59330b307cfcc03425b994d417a93c508def6d46ee12d8"
}

​
Get Public Key with Metamask

Metamask does not currently provide the publicKey directly but it can be obtained by signing a request. 
import { ethPersonalSignRecoverPublicKey } from '@polybase/eth'
import {  } from '@polybase/util'

const msg = 'Login to app'
const sig = await auth.ethPersonalSign(msg)
// Returns a hex string of the public key (65 bytes), you will need to convert to 64 bytes to use
// with Polybase
const publicKey65Bytes = ethPersonalSignRecoverPublicKey(sig, msg)
// Now it can be used with Polybase
const publicKey64Bytes = '0x' + publicKey65Bytes.slice(4)

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Force open signIn modal

By default, if the user is already logged in to your app, then the sign in modal won’t open. Instead, the auth state will be returned immediately. If you’d like to allow the user to change the auth/account they are logged in with, you can force open the modal by passing { force: true } to the signIn function. 
import { Auth } from '@polybase/auth'

const auth = new Auth()

const authState = await auth.signIn({ force: true })

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Sign out

import { Auth } from '@polybase/auth'

const auth = new Auth()

await auth.signOut()

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Ethereum Personal Sign

Ethereum Personal Sign is the signing mechanism used by Polybase (and many other dapps) to authenticate ownership of a public key and to sign data. 
import { Auth } from '@polybase/auth'

const auth = new Auth()

const signatureHex = await auth.ethPersonalSign(data)
You can use the auth.ethPersonalSign() in the Polybase client signer function: 
import { Auth } from '@polybase/auth'

const auth = new Auth()

db.signer(async (data) => {
  return {
    h: 'eth-personal-sign',
    sig: await auth.ethPersonalSign(data)
  }
})

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Listening for updates

Your app can listen for updates in the authentication state, by adding an event listener. This can be useful when a user returns to your website. 
import { Auth } from '@polybase/auth'

const auth = new Auth()

auth.onAuthUpdate((authState) => {
  if (authState) {
    // User is logged in, show button to dashboard
  } else {
    // User is NOT logged in, show login button
  }
})

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Example

Open in CodeSandbox

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React

If you’re using React, you can use our React library @polybase/react to help with control authentication.