jwt decode throws Invalid argument supplied for foreach() on php-jwt and codeignitor 4

Question

I have encoded a token with JWT::encode($payload, $key, 'HS256');

When I am trying to decode it with the same key, it throws an error.

Here is the code:

<?php
 
namespace App\Filters;
 
use CodeIgniter\Filters\FilterInterface;
use CodeIgniter\HTTP\RequestInterface;
use CodeIgniter\HTTP\ResponseInterface;
use \Firebase\JWT\JWT;
use Config\Services;
use Config\MyConfig;

 
class AuthFilter implements FilterInterface
{
  
    public function before(RequestInterface $request, $arguments = null)
    {
        $myconfig = new MyConfig;        

        $key = $myconfig->JWT_SECRET_KEY;
        
        $header = $request->getServer('HTTP_AUTHORIZATION');
        if(!$header) return Services::response()
                            ->setJSON(['msg' => 'Token Required'])
                            ->setStatusCode(ResponseInterface::HTTP_UNAUTHORIZED);
        $token = explode(' ', $header)[1];
 
        try {
            JWT::decode($token, $key, ['HS256']); // it throws error: jwt decode throws 
                                            // Invalid argument supplied for foreach()
        } catch (\Throwable $th) {
            return Services::response()
                            ->setJSON(['msg' => $th->getMessage()])
                            ->setStatusCode(ResponseInterface::HTTP_UNAUTHORIZED);
        }
    }
 
   
    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
    {
        //
    }
}

So this happens every time when I try to decode, but works fine when I encode it.

Answer 1

After spending hours, I went through official documentation (https://github.com/firebase/php-jwt#readme), seems I had to use JWT::decode($token, new Key($key, 'HS256')); instead of JWT::decode($token, $key, ['HS256']);

Answer 2

It works for me like this:

use Firebase\JWT\Key;             // add the library

JWT::decode($token, new Key($key, 'HS256'));