This document provides exercises for part 3 of a security textbook. It lists conceptual exercises asking about advantages and disadvantages of web of trust vs certificate authority trust models and how symmetric encryption can provide authentication, confidentiality, and message integrity. It also provides a programming problem to extend an AES encryption program to compute and verify a MAC on encrypted messages using separate keys for encryption and MAC computations.

1. CHAPTER 16
Exercises for Part 3
Slides adapted from "Foundations of Security: What Every Programmer
Needs To Know" by Neil Daswani, Christoph Kern, and Anita Kesavan
(ISBN 1590597842; http://www.foundationsofsecurity.com). Except as
otherwise noted, the content of this presentation is licensed under the
Creative Commons 3.0 License.

2. Conceptual Exercises
 List three advantages/disadvantages of using a
web of trust model vs. using a certificate
authority–based trust model.
 State how you can use symmetric encryption to
achieve (a) authentication, (b) confidentiality,
and (c) message integrity.

3. Programming Problem
 Extend the AESEncrypter program of Section
12.1.6 to compute and verify a MAC on the
message in addition to encrypting and
decrypting data. Be sure to use different keys for
the encryption and MAC computations.