Verify third party JWT with Laravel - php

Question

I'm using external identity provider to authenticate users, created a SPA client (got client_id & client_secret), configured API with audience & scope, so once users authenticated they will get access_token (will be authorized) to access multiple custom micro-services (APIs).
When my custom API receives a request with a bearer Access Token (JWT) the first thing to do is to validate the token. In order to validate JWT I need to follow these steps:
Check that the JWT is well formed (Parse the JWT)
Check the signature. My external identity provider only supports RS256 via the JWKS (JSON Web Key Set) URL (https://{domain}/.well-known/jwks.json), so I can get my public key following this URL.
Validate the standard claims
Check the Application permissions (scopes)
There are a lot of packages/libraries (i.e. https://github.com/tymondesigns/jwt-auth) to create JWT tokens but I can't find any to validate it using those steps above. Could anyone please help to find suitable Laravel/PHP package/library or move me to the right direction in order to achieve my goals (especially point #2).

Answer 1

I did something similar in the past, I don't know if this may help but I'll give it a try. To use a public key, you should download it, put it somewhere on the disk (storage/jwt/public.pem for example) and then link it in the jwt config config/jwt.php with the ALGO (you can see supported algorithms here
'keys' => [
// ...
'public' => 'file://'.storage_path('jwt/public.pem'),
// ...
],
'algo' => 'RS256',
Then, you should have a custom Guard, let's call it JWTGuard:
<?php
namespace App\Guard;use App\Models\User;
use Illuminate\Auth\GuardHelpers;
use Illuminate\Contracts\Auth\Guard;
use Illuminate\Http\Request;
use Tymon\JWTAuth\JWT;class JWTGuard implements Guard
{
use GuardHelpers;
/**
* #var JWT $jwt
*/
protected JWT $jwt;
/**
* #var Request $request
*/
protected Request $request;
/**
* JWTGuard constructor.
* #param JWT $jwt
* #param Request $request
*/
public function __construct(JWT $jwt, Request $request) {
$this->jwt = $jwt;
$this->request = $request;
}
public function user() {
if (! is_null($this->user)) {
return $this->user;
}
if ($this->jwt->setRequest($this->request)->getToken() && $this->jwt->check()) {
$id = $this->jwt->payload()->get('sub');
$this->user = new User();
$this->user->id = $id;
// Set data from custom claims
return $this->user;
}
return null;
}
public function validate(array $credentials = []) { }
}
This should do all your logic of validation, I used a custom user implementation, the class signature was like:
use Illuminate\Contracts\Auth\Authenticatable as AuthenticatableContract;
use Illuminate\Database\Eloquent\Model;
class User extends Model implements AuthenticatableContract {
// custom implementation
}
Finally, you should register the guard in the AuthServiceProvider and in the auth config
public function boot()
{
$this->registerPolicies();
$this->app['auth']->extend(
'jwt-auth',
function ($app, $name, array $config) {
$guard = new JWTGuard(
$app['tymon.jwt'],
$app['request']
);
$app->refresh('request', $guard, 'setRequest');
return $guard;
}
);
}
then allow it in the config
<?php
return [
'defaults' => [
'guard' => 'jwt',
'passwords' => 'users',
],
'guards' => [
// ...
'jwt' => [
'driver' => 'jwt-auth',
'provider' => 'users'
],
],
// ...
];
You can then use it as a middleware like this:
Route::middleware('auth:jwt')->get('/user', function() {
return Auth::user();
}
Does this sound good to you?

Answer 2

In the end I've used the Auth0 SDK for Laravel - https://auth0.com/docs/quickstart/backend/laravel/01-authorization. Nice and clean solution.