Didn't get past the paywall but, recently a friend had their primary school targeted by blackmailers who took public photos of children and made (I'm told) extremely explicit images with them, threatening to release them if not paid.

What's the defense? Intelligent screening of incoming messages so that the threat never reaches the blackmail target? I imagine they'll find an unprotected channel.

Don't post innocuous images of children ever? Seems like losing.