How does having radio schematics help with penetration and/or traffic sniffing?

[OpenSource Ghost]

Not long ago I ended discussing privacy and security with a (badge-verified) law enforcement "specialist" who stated that understanding physics mattered more than understanding network when penetrating radio connections of any kind and that even "well-encrypted secure WiFi/mobile data traffic could be decrypted with relative ease if radio schematics were already available in LEA databases, but growing use of VPN's did prove to be problematic". The "specialist" wasn't willing to elaborate on that statement, almost as if too much was already said...

Why and/or how would physics-based radio signatures and radio schematics help with traffic decryption? I assume that physics-based information can be used for side channel attacks, but I don't know how or why having radio schematics help with penetrating radio traffic.

 

[Nobu]

Not long ago I ended discussing privacy and security with a (badge-verified) law enforcement "specialist" who stated that understanding physics mattered more than understanding network when penetrating radio connections of any kind and that even "well-encrypted secure WiFi/mobile data traffic could be decrypted with relative ease if radio schematics were already available in LEA databases, but growing use of VPN's did prove to be problematic". The "specialist" wasn't willing to elaborate on that statement, almost as if too much was already said...

Why and/or how would physics-based radio signatures and radio schematics help with traffic decryption? I assume that physics-based information can be used for side channel attacks, but I don't know how or why having radio schematics help with penetrating radio traffic.

Without too much knowledge on the subject, I imagine it could give you an idea of what components might be bleading rf into the transmit path, and some of that information might be useful in determining the key used (or type of encryption, etc).

Edit: You may even be able to get unencrypted datastreams in some instances. At least, I wouldn't be surprised to see that.