Backend Authentication

Backend Auth with a NEAR Wallet

Authenticating users is a common use-case for backends and web applications. This enables services to provide a personalized experience to users, and to protect sensitive data.

To authenticate a user, the backend must verify that the user is who they say they are. To do so, the backend must verify that the user has access to a full-access key that is associated with their account.

For this three basic steps are needed:

Create a challenge for the user to sign.

Ask the user to sign the challenge with the wallet.

Verify the signature corresponds to the user.

1. Create a Challenge

Assume we want to login the user into our application named application-name.

We first need to create a challenge that the user will sign with their wallet. For this, it is recommended to use a cryptographically secure random number generator to create the challenge.

import { randomBytes } from 'crypto'
const challenge = randomBytes(32)
const message = 'Login with NEAR'

Here we use crypto.randomBytes to generate a 32 byte random buffer.

2. Ask the User to Sign the Challenge

The signMessage method needed to sign the challenge is supported by these wallets:

Meteor Wallet

Here Wallet

Near Snap

Nightly Wallet

WELLDONE Wallet

NearMobileWallet

MyNearWallet

Sender

Intear Wallet

The message that the user needs to sign contains 4 fields:

Message: The message that the user is signing.

Recipient: The recipient of the message.

Nonce: The challenge that the user is signing.

Callback URL: The URL that the wallet will call with the signature.

// Assuming you setup a wallet selector so far
const signature = wallet.signMessage({ message, recipient, nonce: challenge, callbackUrl: <server-auth-url> })

3. Verify the Signature

Once the user has signed the challenge, the wallet will call the callbackUrl with the signature. The backend can then verify the signature.

Tutorials

DevKit

Backend Authentication

Backend Auth with a NEAR Wallet

1. Create a Challenge

2. Ask the User to Sign the Challenge

3. Verify the Signature

​Backend Auth with a NEAR Wallet

​1. Create a Challenge

​2. Ask the User to Sign the Challenge

​3. Verify the Signature

Backend Auth with a NEAR Wallet

1. Create a Challenge

2. Ask the User to Sign the Challenge

3. Verify the Signature