Test II, CSCI 277, Fall 2022

Please write your name on the blank below.
The weight for each question is given.
Use as much paper as you wish, but make your answers are legible.
Please label your answers with the question number.
Please answer each question thoughtfully and carefully. Your answers should reflect participation in this class.
When finished, please staple this page on top of your answer pages.

Name: ________________________________

Identification/Authorization
1. [4 points] Differentiate between identification and authentication.
2. [2 points] Which is public, which is private and why?
3. [4 points] Give an example of an identification/authorization pair, identify the roll of each.
Passwords
1. [5 points] If passwords are stored in a one way hash that is impossible to reverse, why are stolen password files a problem? (Provide an answer that demonstrates you have participated in this class).
2. [5 points] If the "salt" for an encrypted password must be provided to allow password authentication, how can the salt increase security?
Other Authentication Methods
1. [4 points] Discuss one problem when using fingerprints for authentication.
Symmetric Key Encryption
1. [4 points] What makes an encryption scheme a symmetric key encryption?
2. [3 points] Name/describe one technical problem with DES.
3. [3 points] Name/describe one political problem with DES.
Public Key/Private Key
1. [4 points] RSA encryption uses the fact that $(m^e)^d \equiv (m^d)^e \equiv m \mod n$. What roles do n, d and e play in this encryption scheme?
2. [6 points] Bob wishes to prove that he received a message from Alice. How could he do so using RSA encryption? You may assume that Bob and Alice have exchanged public keys. Explain your answer.
Certificate Authority
1. [2 points] What role does a CA play in secure message exchange?
2. [4 points] How can a user ensure that they have a legitimate public key for an entity registered at a CA? Provide a algorithm for acquiring such a key.