/**
* @param JWKInterface $key
*/
private function checkKey(JWKInterface $key)
{
Assertion::eq($key->get('kty'), 'OKP', 'Wrong key type.');
Assertion::true($key->has('x'), 'The key parameter "x" is missing.');
Assertion::true($key->has('crv'), 'The key parameter "crv" is missing.');
Assertion::inArray($key->get('crv'), ['Ed25519'], 'Unsupported curve');
}