Question 1: Bob and Alice wish to communicate using symmetric cryptography but do not have a prearranged secret key. What algorithm they can use?

a) DES; b) AES; c)Diffie-Hellman d) Skipjack e) None of the above

Question 2: What is the only cryptosystem known to be unbreakable, when correctly implemented?

a) Substitution Ciper b) stream Ciper c) block Ciper d) ROT3 Ciper e) none of the above