Well if encryption works, it will work for ISIS too.
Sure... But i think an organisation like anonymous would be strong enough to hit them where it hurts: their social media campaign... They can encrypt most things, but not their twitter and facebook. It would be meaningless if they posted encrypted messages on facebook, because it would be useless as a tool to attract easily brainwashed kids.
Unfortunately most brainwashed "kids" they attract via their priests in various big cities over the world.
But I hope that Anonymous can find out something more, like their servers, if any.
Guerrillas are hard to fight, but I am sure they have some central points of command. If those are revealed and hacked, a lot o interesting info will flood out.