As part of the certificate authority, the is an entire system set up for the military that is called Common Access Card. It was put into place by hussein early on and last had an update in '14. The reason to note this is all computers with .gov are required to have software installed as part of a two way handshake before any computer can connect with the intranet at DOD. Anyone can be given the keys, or use existing ones to make more with the right access. Say, clintonemail.com has the software installed for state dept use, has CAs for DOD, with clearances, those same CAs can be spoofed for direct DOD access. How did china get their design for the j-20?
Do need to add that the whole system is connected with what are called bridges, a key word from Q.
https://fpki.idmanagement.gov