Key exchange is a method used to securely share cryptographic keys between parties. This is essential for facilitating secure communication and transactions in systems that rely on encryption. In many cases, two parties wish to communicate privately, but they need to establish a shared secret key first. Key exchange protocols enable them to do this without the risk of the key being intercepted by an unauthorized party. One of the most well-known key exchange methods is the Diffie-Hellman protocol. It allows two users to generate a shared key through a series of mathematical operations, even if they communicate over an unsecured channel. Once the key is exchanged, it can be used to encrypt messages, ensuring that only the intended recipients can decipher them. This underpins much of the security in online transactions, protecting sensitive information from eavesdroppers and attackers. Overall, key exchange plays a crucial role in maintaining privacy and security in various digital interactions.