Which of the following is a cryptographic protocol that allows two parties to establish a shared key over an insecure channel?

The correct choice is Diffie-Hellman (DH) because it specifically provides a method for two parties to generate a shared secret key over an insecure communication channel. This is accomplished through a series of mathematical operations involving large prime numbers and their generators, allowing both parties to independently derive the same key without directly transmitting it.

The significance of Diffie-Hellman lies in its ability to facilitate secure communication between parties who have never met before and do not share any pre-existing secrets. This key exchange mechanism underpins many cryptographic systems and protocols that require secure key distribution.

In contrast, while protocols like RSA and SSL play important roles in encryption and securing communication, they serve different purposes. RSA is primarily a public-key cryptosystem used for securely transmitting messages or encrypting the shared key generated by Diffie-Hellman. SSL, on the other hand, is a protocol used to secure communications over a computer network but employs various cryptographic algorithms, including key exchange mechanisms like Diffie-Hellman, rather than specifically establishing shared keys over insecure channels on its own.

Lastly, the Advanced Encryption Standard (AES) is a symmetric key encryption algorithm, which requires a shared secret key beforehand and does not provide a method for establishing that key over an