I can't remember where I read a longer explanation of this but a quick google search got me to this blog entry http://www.scottaaronson.com/blog/?p=2059 where the topic comes up. I think that for the most part what we civilians know as cryptography is often either a red-herring, a trick, or woefully out of date from the point of view of what the professional state actors know how to do. Anyway you get that impression from declassified documents. Crypto works well enough for commercial and civilian purposes but has no impact on militarized hacking I think. Please correct me if I am wrong but I think this is all by design, even going so far as the NSA putting backdoors in CPUs and suchlike. If they send a company a national security letter that insists on compliance, the company not only has to comply but also can't legally disclose to the public that they complied, so we can't really know the truth here.