Hi @mattclarke, this is a neat idea but I think it's a bit dangerous as implemented.

Canaries are a great idea but by definition, they should not require any action to "fire," but rather inaction.

Unfollowing @the-canary is an action that a Steemian could be ordered not to take. For example, if someone living in the United States were served a National Security Letter, they could potentially be barred from publishing the "unfollow" transaction under penalty of law.

It is extremely difficult, on the other hand, to force an unwilling party to publish a fraudulent canary (at least in jurisdictions with protections against state-compelled speech), and that's why they work. In the same situation noted above, the Steemian could simply refuse to update the canary. Since compelled speech is a big no-no under US constitutional law, the "refusal to update" method seems to be on solid theoretical ground in legal terms, but has not been tested thoroughly in court.

Perhaps a better implementation would be to publish a monthly @the-canary post on which subscribing accounts should publish comments reaffirming their integrity.

Of course, no canary is torture-proof. The closest thing would be keeping a key that is only for signing your canary on some sort of easily destructible medium, which can then be destroyed in some way (chewed, ingested, crushed, etc). This has its own set of problems, but you get the idea.