CompTIA Network+ Practice Test

In which phase of IKE does Diffie-Hellman key exchange occur?

1. Phase one

2. Phase two

3. Both phases

4. None of the phases

The correct answer is: Phase one

The Diffie-Hellman key exchange occurs in phase one of the Internet Key Exchange (IKE) process. This phase is critical for establishing a secure communication channel between two parties by enabling them to generate a shared secret key over an insecure channel. During phase one, the two parties negotiate the terms of their communication, including the cryptographic algorithms they will use. The Diffie-Hellman exchange specifically allows both parties to compute a shared secret, which is used to derive session keys for secure communication. This process depends on the mathematical principles behind Diffie-Hellman, where each party generates their own private key and exchanges public keys, leading to a shared key that remains confidential. Phase two, on the other hand, involves the establishment of the Security Association (SA) and is primarily focused on using the keys generated from phase one to set up secure channels for the actual data exchange, but it does not involve a key exchange method like Diffie-Hellman. Thus, it is clear that the correct answer relates specifically to phase one where the Diffie-Hellman process occurs.