This new research paper caught my eye recently. It's in many ways a response to some of the latest research on how network-level adversaries attack Tor.
With the threat of powerful intelligence agencies, like the NSA, looming large, researchers have built a new Tor client called Astoria designed specifically to make eavesdropping harder for the world's richest, most aggressive, and most capable spies to track Tor users from start to finish.
Astoria reduces the number of vulnerable circuits from 58 percent to 5.8 percent, the researchers say. The new solution is the first designed to beat even the most recently proposed asymmetric correlation attacks on Tor.
Designed to beat such attacks, Astoria differs most significantly from Tor's default client in how it selects the circuits that connect a user to the network and then to the outside Internet. The tool, at its foundation, is an algorithm designed to more accurately predict attacks and then securely select relays that mitigate timing attack opportunities for top-tier adversaries.
I think it's a really interesting read and I like the idea they are posing but nothing will ever be 'NSA proof' IMHO.
I think everything is crack-able, it just takes the skills and the knowledge to do so.
That's how we improve. The current system is compromised in some way, we make something better, rinse and repeat.