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Authentication
Login

Login API

📘
Full Code Repo - https://github.com/aave/lens-api-examples
🌿

Lens API - https://docs.lens.xyz/docs/login

Login is basic functionality of every social application. In order to authenticate a user on Lens Protocol, you need to use two APIs. The first one is to generate a challenge from the server and seconds one is to sign that challenge using your wallet and send it back to server.

If the signature matches, the server will return a access token and refresh token and that can be used to authenticate the user.

Generate a challenge

As mentioned above, the first step is to generate a challenge from the server. You must request a challenge form the Lens server by providing the your wallet address and the server responds with a text that can be later signed by the your wallet to prove the ownership.

The challenge text will expire after 5 minutes, if it expires you must request a new challenge. Once you have used the challenge to generate a JWT token, it will not work again.

API Operation

Here is a example of how to generate a challenge:

let address = '0x...';

Lens.getChallenge(address).then((response) => {
  console.log(response);
});

API Response

{
  "data": {
    "challenge": {
      "text": "DemoApp wants you to sign in with your Ethereum account: 0x...",
  }
}

Sign a challenge

Once you recieved a challenge from Lens' server, you can sign the challenge using your wallet and send it back to the server with your address.

In return, you will get a access token and refresh token from the server.

  • The access token will be used to authenticate the user and the refresh token will be used to generate a new access token when the old one expires.

  • The access token will expire after 30 minutes and the refresh token will expire after 1 days.

API Operation

Here is an example of how to send a signed challenge to the server:

Lens.Authenticate(address, sign).then((response) => {
  console.log(response);
});

Hooking login together all in one

Here is the full code that generates a challenge, sign it and recieves a access token and refresh token from server using wagmi in a react app.

import React from 'react';
import { useAccount, useSignMessage } from 'wagmi';
import { Lens } from 'lens-protocol';
export default function Login() {
  const { address } = useAccount();
  const { data, error, isLoading, signMessage } = useSignMessage({
    onSuccess(data, variables) {
      // Verify the signature
      VerifySignature(data);
    },
  });

  const authenticate = async () => {
    // Getting the challenge from the server
    const data = await Lens.getChallenge(address);
    let message = data.data.challenge.text;
    // Signing the challenge with the wallet
    signMessage({ message });
  };

  const VerifySignature = async (sign) => {
    // Sending the signature to the server to verify
    const response = await Lens.Authenticate(address, sign);
    console.log(response);

    // {
    //  data: {
    //   authenticate: {
    //    accessToken: "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjB4YjE5QzI4OTBjZjk0N0FEM2YwYjdkN0U1QTlmZkJjZTM2ZDNmOWJkMiIsInJvbGUiOiJub3JtYWwiLCJpYXQiOjE2NDUxMDQyMzEsImV4cCI6MTY0NTEwNjAzMX0.lwLlo3UBxjNGn5D_W25oh2rg2I_ZS3KVuU9n7dctGIU",
    //    refreshToken: "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjB4YjE5QzI4OTBjZjk0N0FEM2YwYjdkN0U1QTlmZkJjZTM2ZDNmOWJkMiIsInJvbGUiOiJyZWZyZXNoIiwiaWF0IjoxNjQ1MTA0MjMxLCJleHAiOjE2NDUxOTA2MzF9.2Tdts-dLVWgTLXmah8cfzNx7sGLFtMBY7Z9VXcn2ZpE"
    //   }
    // }
  };

  return (
    <div>
      <button onClick={authenticate}>Login</button>
    </div>
  );
}
Installation
Refresh Token