Final answer:
The Diffie-Hellman algorithm allows two parties to securely establish a shared secret key, which can be used for symmetric encryption, without the need to exchange private keys.
Step-by-step explanation:
The purpose of the Diffie-Hellman algorithm is to enable two users to securely reach agreement about a shared secret that can be used as a secret key for subsequent symmetric encryption of messages. This process involves each party generating a private and a public key. They then exchange their public keys and use their own private key to compute the shared secret, which is the same for both due to the mathematical properties of the algorithm. Thanks to this method, even if a malicious actor intercepts the public key exchange, they will not be able to deduce the shared secret without the private keys, which are never exchanged. This is why the Diffie-Hellman algorithm is critical in modern cryptography for establishing a secure communication channel