Which tools the spies can't crack The Tor network, which was developed for surfing the web anonymously, is considered to be a "major" problem, as is Truecrypt, a program for encrypting files on computers. A combination of Tor, the instant messaging system CSpace, and a system for internet telephony called ZRTP is categorised as "catastrophic" for the NSA and its partners, resulting in a "near-total loss/lack of insight to target communications".

http://www.smh.com.au/it-pro/security-it/revealed-the-encryption-tools-spies-can-and-cant-crack-20141229-12f0sh.touch.touch.html