[ds9]

It's not exactly illegal, and the new secret-orders tactics are the government's workaround.

In the 1990s there was a series of political/legal conflicts over encryption, which was about to go mainstream (the whole episode is now referred to as the "clipper chip" controversy). The USG wanted strong encryption without backdoors banned, and everyone to use instead a set of encryption protocols which would have provided keys for the government (the "key escrow" idea), and the USG would promise not to abuse the power to decrypt everyone's communications.

Some heroic technical people worked around that and actually exported what eventually became PGP/GPG on paper to take advantage of a loophole in the ban. The controversy faded and the civilian right to non-backdoored, strong encryption became the nominal law and policy.

Since then the USG has been working to undo and reverse this situation by any means it can find. What it's come up with is (a) the NSA mass-wiretapping regime (actually a continuation Echelon and several other prior, longstanding mass-surveillance schemes) and (b) the set of legal tools applied to Lavabit.

And they've mostly succeeded. Secure communication is theoretically legal, but if the government can coerce encryption keys, secure communication is defacto subject to being stopped anytime the government takes an interest in someone. And while providing secure comms as a service is technically still legal, if the feds can demand a combination of trojaning the service and concealment of the subversion from users, then they have effectively banned secure communications in practice, while maintaining the written law as-is.