&gt; No, it&#x27;s the code for the new YubiKey 4, which has been closed off.<p>yk4 firmware was never released; that particular issue is about NEO&#x27;s openpgp applet.<p>&gt;Ideally, you can build and flash the firmware yourself.<p>You couldn&#x27;t do that with NEO(except from early dev version) as global platfrom management keys are unknown, which makes it impossible to delete&#x2F;upload applets. I actually tried to get dev. version but they redirected me to NXP who never answered.