This is going to branch into a bunch of separate questions.....here is some background for the question:
The Rijndael algorithm was crowned the new AES by Uncle Sam for sensitive, but unclassified info (128-256 key+block sizes through 10-14 rounds) . The Kerckhoff school of thought is "Let the algorithm be known, just keep the key secret". Uncle Sam doesn't agree.
I work in a military environment and I have 3 computers on my desk. One is NIPR (not secret), one is SIPR (Secret), and one is Centrix (Multinational Allies Secret).
Is the encryption that categorizes these systems hardware? Did it come with hardwired into my Dell laptops? Did they attain an Orange Book evaluation of A1 (verified design) or EAL7 from the Common Criteria?
OR....Is it just software/network connectivity based. So, when I baseline a computer and slap a green NIPR tag on it, or a red SIPR, it just means that they are "connected" to a safer network.
So is the encryption that surpassed the AES standards for computers labeled "Secret" applied at hardware, software, or network levels? If the answer could be put into an OSI layer method type of explanation, it would be cool.