Setting algorithm at runtime does not update header "alg"

[palfaro91]

I'm trying to create a custom token using Tymon-JWT with a different algorithm than the one defined in the config file (jwt.php).

public function generateCustomToken($data) {
    $claims = [...] // standard claims in a JWT token 
    // set the algorithm
    JWTAuth::getJWTProvider()->setAlgo('RS256');
    // custom signer as well
    JWTAuth::getJWTProvider()->setSecret($data["signer"]);

    // if I log it here the correct algorithm is displayed
    Log::info(JWTAuth::getJWTProvider()->getAlgo()); == 'RS256'

    $claims = new Collection($requiredClaims);
    $payload = new Payload($claims, new PayloadValidator());
    $tkn = JWTAuth::encode($payload);
    return $tkn->get();
}

So I change the algorithm and log it and it shows my value but when I decode the token the header "alg" displays the algorithm set in the config file.

Does this mean that it is not using RS256 to encode the token? How do I go about changing that algo value?

Your environment

Q	A
Bug?	yes
New Feature?	no
Framework	Laravel
Framework version	5.8
Package version	1.0.2
PHP version	7.3.3

Steps to reproduce

Use the code above

Expected behaviour

setting JWTAuth::getJWTProvider()->setAlgo('RS256'); should also change the header "alg" to reflect the algorithm used

Actual behaviour

The algorithm set in the config file is displayed as the value rather than the custom one I set at runtime