OTTAWA—By the time the next federal election rolls around, Bernie Farber, chair of the Canadian Anti-Hate Network, won’t be casting a ballot. That’s not because he has no interest in doing so: it’s because he’s in the process of deregistering himself as a voter out of fears his personal information could be shared with hate groups. “I’m a Canadian citizen that has voted since I’ve been allowed to vote. And if I want to … feel safe and I want my family to feel safe, I have to do this,” said Farber, who has previously been targeted by white supremacist...