[pluma]

Canaries still work, though, don't they?

I.e. put up a cryptographically signed and timestamped statement that you haven't received a request, then don't update it (or simply take it down) once you receive a request.

Don't some open source projects do this?

[arebop]

Canaries are not well-settled in law [https://www.eff.org/deeplinks/2014/04/warrant-canary-faq].

[Crito]

Correct. However: https://news.ycombinator.com/item?id=6680780 or: https://news.ycombinator.com/item?id=8337001

Another law of successful (or at least apparently effective) "law hacking": http://en.wikipedia.org/wiki/Pretty_Good_Privacy#Criminal_in...

Common law systems really aren't as simple as "only intent matters, absolutely nothing clever is tolerated", as many suggest. The problem is mostly that, whenever computers are involved, people involved in the justice system seem to have their sensibilities bizarrely warped. Removing the technological element is likely the best way to get people to think about things sensibly. It is not so much "legal trickery" as it is "framing the matter in terms that the court already understands".

[golemotron]

I've always thought that law attempts to assert its primacy over law by ignoring it.

[AnonNo15]

You can do it right now by embedding such message in Bitcoin blockchain. It will give you tamper-proof and timestamped message.

[rsync]

A bit easier is to simply include a news headline in the signed message:

http://www.rsync.net/resources/notices/canary.txt

It's not as sophisticated as the blockchain, etc., but about as good - if you pick sensitive pieces of financial news it's clear you could not have known about them in advance. Or sports results.