We often say that the Internet is decentralized, which is more or less true, but it is not atomized. There are perhaps a few thousand large units called Autonomous Systems (AS) that make-up the Internet, and they relate to each other with Border Gateway Protocols.
BGP is, essentially, a type of "handshake" protocol: I acknowledge you, do you acknowledge me? Who is connected beyond you? The problem with BGP is that it is not verifiable. This isn’t a big problem – as we know, the Internet works just fine nearly every day – but on rare occasion something does go wrong. From a controller’s standpoint, however, BGP is a huge problem, because it cannot be grasped at a single point.
Enter SecureBGP (BGPSEC) Under this scheme, key exchanges between border gateway routers are involved, to verify that the other router is who it says it is. The problem here is that someone will want to be the official key creator and holder… which means the state. And the US government is working very hard to build this. (They already have a domain name version called DNSSec.)
If the key certificate authority for BGPSEC is anything like SSL certificate authorizers, then each layer of key provider will control the keys below it. That means that specific servers or groups of servers can be disconnected from the Internet within minutes. But even if that type of hierarchy is not part of the code, it is close to certain that AS groups will comply with orders, especially if disobedience means they will be shut down entirely. [Emphasis added]
So, yes, the Internet Kill Switch will work, sorry to say.
It seems to me that the Internet is too large and complex for the U.S. Government to control absolutely. Programmers and hackers, unencumbered by bureaucratic restraints, will easily stay ahead of the spooks both on defensive and offensive terms (e.g., encryption and viruses).
And the problem is not merely technical but cultural. Two generations of Americans are now accustomed to a free flow of electronic information. They are habituated to spotting and avoiding censorship - even private censorship for copyright or ideological reasons - wherever it occurs. Block one avenue of knowledge and they actively, almost instinctively, seek or create another avenue, in an independent and decentralized manner. The ruling class, thinking in the old terms of mass culture and mass obedience, doesn't grasp this critical point. Nor does it comprehend the depth and breadth of popular resentment and suspicion it has provoked by years of lying and plundering. Cyber-censorship imposed for the "public good" will be seen exactly for what it is: a power grab by a pack of sanctimonious crooks. The desire to resist and foil it will be almost obsessive. Think of Prohibition, but this time with nearly everyone below the age of 50 a regular heavy drinker.
None of this means that our rulers won't be stupid enough to try. I presume they will hit the "kill switch" before, during, or after the first massacre of street protesters. They will make high profile busts of people engaged in "cyber-terrorism". They will accomplish or attempt still more evil things. But it will not save the system.