About Quilibrium and Components

Level 2: Storage and Compute

Each tree house has a lot of stuff in it, sometimes the same stuff others have, sometimes it's things only you have (like that cool four foot tall robot), but if others knew what you have, they might try to sneak into your tree house and steal it. What if you were staying over at a friend's tree house and wanted to show off your robot? How can you prove it's yours, or that you even have it, when you're away from your home base?

Let's take a moment and pretend that there is always someone at every tree house, so the next steps are possible. You could send a message back to your tree house and say "send the robot over to Bobby's tree house by bucket", and a bucket holding your robot would come flying over the wire, but there's only one of these, and you don't want to lose it in transit, like when the last baseball game sent a ball into Mrs. Benefield's yard and it was lost forever to her very angry dog. So instead, someone in your tree house takes a polaroid of your robot, and sends that over by envelopes inside of envelopes, but this time, actually using envelopes along with codewords, zipping from tree house to tree house, until it hits the one you're at.

But that's just a photo. It could have been taken at any time. How do we know that was yours and not a photo you got from another tree house? To prove this, Bobby comes up with a few random words ("paraglider rabbit snake beach"), gives them to you, and you send a message back to your tree house: "send a photo of the robot over to Bobby's tree house, include 'paraglider rabbit snake beach' in the photo", and a few moments later, the envelope arrives, ready to prove you are indeed the coolest kid in the neighborhood.

But there's a small problem in this. If anyone can ask your tree house for things that you might have, they can figure out what you have. Let's imagine instead you are really organized, and have everything packed away in chests that are bolted to the floor. Each chest has its own key, and you have a big key ring you carry around with you so only you can open the chests (and so nobody can just climb into your tree house and walk away with your stuff!). This time, you send the key with no message of the contents inside the chest or which chest to open, only saying a few of the chests it might be in. Then your helper at your tree house will have to try out the chests until they find the right one, and send over the photo, along with closing the chest and returning your key.

This would almost work, but now whoever is currently in your tree house knows which chest it was, and what's inside it. But we're close to the answer. Let's say instead, each chest actually has a camera inside it (with a flash, because, y'know, it's dark), a slot for a message to poke through so it can show up in the photo, and the camera actually puts the image in the envelopes for you. The key only activates this contraption, and you end up with an envelope (with the photo inside it), noting which chest it was. If the key wasn't meant for the chest, the photo looks like TV static. They have to try all of the chests you specified, get a bunch of envelopes back, and stuff them all (with the key) inside a bigger envelope, inside another envelope, and so on, and send that back. You get back all the envelopes, but you know which one is the right one, open it, and show the proof of your super cool robot (Oblivious Transfer and Lookup).

So you've got a super cool robot at your tree house, you proved it, but how do we know it's your robot, has been there for all six weeks you've been bragging, and not a friend's that was there at that exact point in time to help you look cool?

Let's revisit our tree house network. One way we can know that the tree houses are connected is if they all agree to a code phrase at a specific point in time. Let's say, every day, these tree houses send out a random word to prove this, that is the previous days word, encoded using the special code books, so now it's a new one. Each tree house does this, and once everyone has sent theirs, you sort the words in the order of each tree house owner's name, alphabetically. Now you have a big random phrase. And those chests all have slots for random phrases. And you have a key to take a photo of each item in each chest. So once a day, you create a big stack of envelopes, proving you have those items. So now, you can ask your tree house to send over a copy of those envelopes for six week's worth of time, and now you have your proof that those six weeks of bragging rights were rightfully yours (Verifiable Delay Function, very simplified).

But wait, couldn't you just save those words and do that all in one step to fake it? We change the process a little bit here. Instead of sending over those envelopes all at once, these envelopes are sent every day. Without the code to decode the contents of the envelope, it's just random noise, but when we're over at the other tree house, we have the power to decode the contents and prove how long it's really been. Now your six weeks of bragging rights are proven to every tree house in the network, and nobody even knows it until you decide to show it (Proof of Meaningful Work).

Reference

• "ELI5: Quilibrium" on Paragraph, 17 May 2024 - https://paragraph.xyz/@quilibrium.com/eli5-quilibrium