Because of the known risks of the unix password system, the sunos-4.0 documentation recommends that the password ? le be removed and replaced with a publicly readable ? le called /etc/publickey. an entry in the ? le for user a consists of a user’s identi? er ida, the user’s public key, pua, and the corresponding private key pra. this private key is encrypted using des with a key derived from the user’s login password pa. when a logs in, the system decrypts e(pa, pra)to obtain pra. (a) the system then veri? es that pa was correctly supplied. how? (b) how can an opponent attack this system?

Jason typically uses the internet to buy various items. it the total cost of all of the items ordered, at one time, is $250 or more, then the shipping and handling is free, otherwise the shipping and handling is $15 per item. design an algorithm that prompts jason to enter the number of items ordered and the price of each item. (remember cost = number of items order times price) the algorithm then outputs the total billing amount including shipping and handling. your algorithm must use a loop (repetition structure) to get the number and price of each item. write this in algorithm format not program code format.