Why would an organization like the DoD prefer to use its own Root Certificate(s)?

Question

While browsing some US military and governmental sites, I noticed their HTTPS connection to rely on DoD Root Certificates. As most of us know, web browsers are pre-loaded with a default set of root certificate authorities which usually does not include the DoD Medium Assurance and Class 3 Root Certificate Authorities among its list of Intermediate and Trusted Root CAs. As a result, web browsers do not recognize the DoD as the Certificate Authority and pop up according warnings.

As most related sites show and explain (eg at http://mrmc.amedd.army.mil/index.cfm?pageid=ssl and/or http://www.dau.mil/faq/pages/dodcerts.aspx and/or http://www.forge.mil/Faqs.html#faqs14) the expected certificate(s) can be installed manually or via an install tool; but that obviously expects the user to put in time and efforts, while fiddling with things I personally wouldn’t expect a “user/client” to have to fiddle with in the first place. Especially, since downloading the root certificate (or using the installers) seems to be open to several (MitM) attack vectors.

At first glimpse, this doesn’t seem to be all too different from creating your own root certificate and forcing your users to download and install your self-signed certificates so that they can browse your (civilian) website securely and without nagging warnings. Normally people thinking along these lines are trying to be – let’s just call it – “cheap”, but I doubt that’s a valid reason when we’re talking about US military sites. I bluntly assume that the DoD doesn’t have money problems that would prevent them from buying certificates from well-established CAs (like the rest of us do).

This makes me wonder… what are the potential advantages for an organization like the DoD that might explain why they’re using their own root certificate(s)? Or – looking at it from another angle – are there any disadvantages if an organization like the US Department of Defence would rely on the typically known and used “public” Root CAs?

Answer 1

They do rely on generally available CA root certs for sites that are expected to be generally avaiable to the public over HTTPS. See https://www.army.mil for one prominent example.

However, the DoD has a significant internal CA infrastructure and they perfer to leverage that instead for sites that either aren't intended to be served over HTTPS at all (like your https://mrmc.amedd.army.mil/ example, where HTTPS requests are simply 30x'ed back to http) or sites that are designed for internal use by folks on DoD equipment like http://www.dau.mil (which requires a CAC [DoD-issued smartcard] for authentication as well) or http://www.forge.mil/.

Answer 2

The DoD - and other government agencies - do typically create their own security realm (certs, smart-cards, dongles, etc .) in order to implement rapid security containment protocols.