Canada Revenue Agency has a website about how to protect yourself against identity theft, which you might find of interest. It talks about things like never providing your personal information by Internet or e-mail. CRA never asks you to provide that type of information by e-mail. Anyway, there's a list: keep your access codes, your user IDs, and your PIN secret, keep your address current.... There are a bunch of things here and it talks about how to minimize your risk by protecting your SIN, immediately reporting lost or stolen credit cards, that sort of thing. We do have a reference that you might find useful.
On April 8th, 2014. See this statement in context.