Member-only story
The Definitive Guide to ZK
Mapping the Zero Knowledge Landscape
One of the best scenes in cinematic history comes from The Princess Bride.
Displaying his discipline, bravery, and skill through a suspenseful series of tense 1 vs 1 fights with the 3 men who kidnapped the Princess, Westley (the protagonist) has defeated the first 2 men and comes face to face with the final boss, Vizzini, the leader of the crew.
Vizzini realizes he is no physical match for Westley, and holds the princess at blade point to keep the hero at bay. Westley reasons with Vizzini, and the two agree to have a battle of wits, where Westley will poison one of the two glasses of wine on the table between them, then Vizzini will choose which glass each of them drinks.
The winner keeps the princess, and the loser dies!
As Vizzini deliberates aloud to derive which glass he should drink, and pokes to trick Westley into revealing which was poisoned, he knows a few things for fact:
- Westley did have Iocane Powder
- Iocane Powder is deadly
- Westley took both cups of wine out of his sight by turning around
- The Iocane Powder container was empty when Westly turned back around
- Both cups were returned to the table
Once Vizzini makes his choice, both drank as agreed… and he is right!
But — Vizzini never thought to guess that Westley had poisoned both cups! And Vizzini falls over dead.
If the battle of wits utilized zero knowledge proofs, however, Vizzini could have checked if one cup was poisoned and found out that not just one single cup had been poisoned. And how different the story may have been!
In this story, I will briefly outline what Zero Knowledge is and what it solves before mapping the Zero Knowledge landscape. Drink at your own pace!
