This is the second time I've read this Ali Baba paper and I'm pretty sure I got hung up on this, too. And I don't see what that property is good for (though I

This is the second time I've read this Ali Baba paper and I'm pretty sure I got hung up on this, too. And I don't see what that property is good for (though I am aware that other people do). Maybe the paper should have a preface. It might work for entertaining someone who already knows all about zero knowledge proofs, but it doesn't seem to do much to educate those who do not.