1. The problem statement, all variables and given/known data Determine which of the following protocols are insecure against replay attack , and explain why: (a) A → B : username, password (b) A → B : username, h(timestamp, password) (c) A → B : username, timestamp, h(password) (d) A → B : username, h(password), h(timestamp) 3. The attempt at a solution I know a is insecure, b is secure but I am not certain about c and d. Off the cuff, in C it seems that h(password) can be replicated as its in the open, as can timestamp, but then if timestamp can be replicated so can h(timestamp). No? I guess my answer is that a,c and d are all insecure, so if possible can someone provide any input on this?