Computer Science // Cryptology

Please Expain and label each answer

4. IKE has two phases, Phase 1 and Phase 2. In IKE Phase 1, there are four key options and, for each of these, there is a main mode and an aggressive mode.

a. What are the primary differences between main mode and aggressive mode?

b. What is the primary advantage of the Phase 1 digital signature key option over Phase 1 public key encryption?