Skeleton Key: Any trusted key system can serve time
Symmetric key encryption uses a shared trusted key. The reported title for this issue was 'Missing key check allows impersonation between authenticated peers' and the report claimed 'A key specified only for one server should only work to authenticate that server, other trusted keys should be refused.' Except there has never been any correlation between this trusted key and server v. clients machines and there has never been any way to specify a key only for one server. We have treated this as an enhancement request, and ntp-4.2.8p6 includes other checks and tests to strengthen clients against attacks coming from broadcast servers.