"Nick, our programming ecosystem barely satisfies the basic principles of software fault tolerance, much less self-healing systems. High assurance? Multiple independent levels of security (MILS)? Covert channel resistance? Completely out of the question!"
Original high assurance systems were done with Pascal, etc. Not much required in terms of programming past type and memory safety, esp strong interface checks. Plus easily understanding how that language becomes code with ability of compilers to transform it (eg auto-insertion of checks). More about a clear description of how it works, clear security policy, evidence they correspond, and implementation that maintains the same. As in another comment in this thread, small changes in hardware or OS's alone would create great increases in security.
Far as the other requirements, software MILS just takes a microkernel with capabilities, periods processing, virtualizable hardware, and the right scheduler. A covert channel analysis via Kemmerer's Shared Resource Matrix can be done by a junior staffer with guidance and little time. That usable, prototypes of secure systems were done by small academic teams with 1990's and early 2000's tech shows it's well within reach of today's programmers. There's just an issue of willingness. Just look back at all the times I wrote up a secure-by-design system and how many people jumped on bandwagon to try to build their own. I can count them on my hands.
"Yet one must not discount that how 0-days are even procured can involve questionable deeds."
That's the subversion risk. The EAL6-7 development processes going back to Orange Book are designed to partly counter that. I add certified compilation, mutually suspicious parties doing analysis, diverse hardware, and so on in my requirements. Gotta address it all. Teams with little resources should focus on ability to detect, trace, and recover rather than prevent. Prevent what they can but only so much staff and time...
"the property of domestic surveillance is not a unique event or something that can be eradicated, but a constant cyclical factor akin to a business cycle that may only be mitigated."
That's an interesting thought. There have been cycles in my country. What worries me is the cyclical nature seems to be ending. We haven't seen the mass protests of police state activity that we wanted. The abuses revealed by Manning and Snowden led to griping followed largely by inaction. We've only seen American power increase even after the parties changed. The 180 of Obama administration on the key issues further suggests strong, covert influence that exists across parties and time. I wished we got something like Iceland in 2008 but America is a fake democracy: people did nothing, are mostly doing nothing, and TPP situation is set to confirm that trend. It's the new cycle.