Error when decoding a JWT with JWK set

[Nahuel Scarlato]

I am trying to decode a JWT with a JWK set and get the error "kid" invalid, unable to lookup correct key from JWT::getKey() for the following code:

$jwt = 'eyJraWQiOiIyMDE5LTA1LTIyVDIwOjQwOjM4Ljc4MS5lYyIsInR5cCI6IkpXVCIsImFsZyI6IkVTMjU2In0.[...]'
$keys = file_get_contents(self::JWK);
$jsonKeys = json_decode($keys, true);

// This filtering was needed otherwise when parsing the keys it would fail. I feel like it should fail and continue trying with other keys of the array...
$jsonKeys = array_filter(
    $jsonKeys['keys'],
    fn ($key) => isset($key['kty'])
        && isset($key['crv'])
        && $key['crv'] === self::JWT_ALGORITHM_CURVE
);

$jwtSet = JWK::parseKeySet(['keys' => $jsonKeys], 'ES256');
$decodedToken = (array) JWT::decode($jwt, $jwkSet);

I checked the JWT on JWT.io and I can see the 'kid' header.

I tried decoding with only one key changing the code to $decodedToken = (array) JWT::decode($jwt, array_shift($jwkSet)); and it worked fine. Same as when parsing keys, I believe it should be able to handle several keys (if one fails, try the others).

I don't think I am doing something wrong, but in case someone sees something odd please correct me.