[keycloak-dev] Migration of old offline tokens

We have a bug that offline tokens issued in the old release (eg. 1.9.8) don't work after migration into the new release and can't be successfully refreshed. JIRA is https://issues.jboss.org/browse/KEYCLOAK-4140 . Reason is, that old offline token don't have KID in the header, but currently we require KID to be present, so we can lookup correct key. I wonder about possible solutions: 1) If KID is not present in offline token, then just look for the realm active RSA key and use that one for the verification. This is easier and I've sent PR for it now https://github.com/keycloak/keycloak/pull/3752 . However there is one small limitation though, that if admin changes the active realm key, the old offline tokens won't work (even though the old publicKey is still valid, it is just not active). So seems that if we go with this one, we should add a note to the migration guide about this limitation? 2) Iterate over all realm RSA keys and try to verify token with any of them. This won't have the limitation above, but it's more complex though. IMO the limitation is acceptable, considering that it's just about backwards compatibility. So I would rather go with simpler 1. WDYT? Marek