In the following setting, Alice and Bob would like to share a secret key for their symmetric cryptosystem. First, Alice chooses a big prime number p and a generator g for the corresponding cyclic group (Z^_P), and publishes this information. Then each party participates in building the shared secret key. 1. Based on what assumption this protocol is secure in the presence of passive adversary? 2. Is this protocol secure having an active adversary in the channel? why