How to blend in within a group of signers? A short story on how ring signatures work:


-Imagine a big dark forest 🌲 in which you want to blend in with N friend. In this forest it is easy to go forwards, but hard to go backwards since you get lost easily (it's your private key!)
-You want to show that someone in that group of friends knows his own private key 🗝️ without revealing who
-Let's say it is you, who knows this private key and wants to blend in
-To do so, you all pick a random spot in the forest
-You then shoot a flare gun from your own spot
-One of your mates sees the flare gun🔫 shining a random amount of times in the sky
-He moves this random amount of steps forward and shoots his flare gun, which again, shines a random amount of times
-The next person does the same thing, etc...
-When the final flare is shot, you rewind your steps by the amount of times it shined. The loop is now closed 🔃!
-Now you pretend with your mates that nobody knows who shot the first flare 🎭
-You pick somebody at random, say Josh, within the group, and pretend it was him who shot the flare first and had to go backwards
-You write down the amount of flare shines Josh saw and had to move forwards by. You also write his position before he moved forward. After Josh shot, Jake had to move forwards, you note his original position. Same for Joshua after him, etc... until you come back to Josh


And that is, in vague terms, how a signer (the guy who went back a certain amount of steps) signs a ring (all the N guys with him). Notice how we don't know for sure that Josh took the first shot and went backwards, but the loop is still closed! 🔎


Here is how you verify the signature is valid:
-Of course, the flares don't actually shine at random, it depends on where they are in the forest 🚩
-You go to this Josh's spot and move forwards by the given flare number. Then you shoot a flare, teleport to Jake's position, and move the amount of times it shined. Etc... until you loop around. If the number of time the last flare shines is the same as the one given to you in the first place, the ring signature is valid. 🟩


Thanks for reading btw :)