Distance-bounding protocol
A distance-bounding protocol is like a secret handshake that helps you figure out how far away your friend is from you.
Imagine you and your friend are both wearing special bracelets that can talk to each other. When you want to greet your friend, you hold out your hand and your bracelet sends a secret message to your friend's bracelet. Your friend's bracelet gets the message and sends a message back to you.
But here's the tricky part: your friend might be really far away or might be pretending to be someone else with a similar bracelet. To make sure your friend is who they say they are and that they're close enough to you, your bracelets use some special tricks.
One trick is called time-of-flight. When you send your message, your bracelet also starts a timer. When your friend receives the message, they send a message back and start their own timer. Based on how long it took for both messages to travel between the bracelets, you can figure out how far away your friend is.
Another trick is called ghost detection. Imagine someone else was also wearing a similar bracelet and tried to pretend to be your friend. If they were far away, they wouldn't be able to respond as quickly as your friend. And if they were close, they might try to send a fake message at the same time as your friend to confuse you. Your bracelets can detect these ghost messages and ignore them, making sure you only talk to your real friend.
So by using time-of-flight and ghost detection, your bracelets can help you greet your friend safely and securely, making sure they're really there and close by.
Imagine you and your friend are both wearing special bracelets that can talk to each other. When you want to greet your friend, you hold out your hand and your bracelet sends a secret message to your friend's bracelet. Your friend's bracelet gets the message and sends a message back to you.
But here's the tricky part: your friend might be really far away or might be pretending to be someone else with a similar bracelet. To make sure your friend is who they say they are and that they're close enough to you, your bracelets use some special tricks.
One trick is called time-of-flight. When you send your message, your bracelet also starts a timer. When your friend receives the message, they send a message back and start their own timer. Based on how long it took for both messages to travel between the bracelets, you can figure out how far away your friend is.
Another trick is called ghost detection. Imagine someone else was also wearing a similar bracelet and tried to pretend to be your friend. If they were far away, they wouldn't be able to respond as quickly as your friend. And if they were close, they might try to send a fake message at the same time as your friend to confuse you. Your bracelets can detect these ghost messages and ignore them, making sure you only talk to your real friend.
So by using time-of-flight and ghost detection, your bracelets can help you greet your friend safely and securely, making sure they're really there and close by.