Hi there.

Subscribing using a token:

So here I create/update the topic:

If it has private: true, will never be received by the subscriber.

the token/key is the same for both publisher and subscriber.

JWT:
eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOlsiYWRkUHJvZHVjdFRpdGxlIl19fQ.GB8yj7zhtYFw9-z94YGfQEGOqDdKMCqCb3E_7eYzTSU

Oh made it work now :D
So, writing here, if anyone else might run into same trouble of understanding same as did I.

When you generate a token to send to the client in the front end, do this:

$token = JWT::encode([
                'mercure' => [
                    'subscribe' => ['myTopic'],
                ],
            ], 'mySecret');
            
             return $token

JWT::encode is from Firebase\JWT;

Then, this token need to be used in the Authorization with Bearer, or in the cookie.

PS. if you do:

JWT::encode([
              'mercure' => [
                  'publish' => ['myTopic'],
              ],
          ], 'mySecret');

then this token can be used to publish a topic.
Cheers :)