[christo]

The fact that the agencies have to apply pressure to obtain keys proves that the crypto is working.

Therefore, if you have, use and keep secret your own keys, the best-resourced intruders cannot practicably get your data.

Of course, http://xkcd.com/538/

[ctdonath]

AKA rubber hose cryptanalysis: http://en.wikipedia.org/wiki/Rubber-hose_cryptanalysis