Key-agreement protocol

A key-agreement protocol is like a secret code between two people. It makes sure that only the two people have access to the same secret. To do this, it uses math puzzles that only the two people know how to solve. For example, if Sara and Bob want to share a secret, they can agree on using a key-agreement protocol. Sara and Bob will both choose a secret number. They use the secret numbers to solve a math puzzle together. If they get the same answer, then they know that both of their secret numbers were the same and they can use that secret number to share their secret information!