How strong is your 'locked' box? It's only a bunch of 1s and 0s.
I wouldn't be surprised. Basically 9/10 people that study cryptography in the US end up working for the NSA. Look at the NSA's budget, and then look at how many cryptography professors there are.
However, that said, IF they managed to decrypt AES somehow, they are severely limited in what they can do with that information. Basically anything they do with the decrypted data has to in no way alert anyone that they have that capability.
So that data DEFINITELY can't be used in court, nor for a whole array of other more covert operations.
It seems unlikely in the extreme that the NSA is both so far ahead of the rest of the world, and so sure that their discoveries will not be replicated for decades.
Sources: http://arxiv.org/ftp/arxiv/papers/1003/1003.4085.pdf http://delivery.acm.org/10.1145/360000/358718/p465-merkle.pd...