Homework 1:

(please finish with typing and submit a hardcopy. You also need to show with some details how you solve a calculation or encryption/decryption problem)

Problems.

Chapter 1: 1.a, 3,

Chapter 2: 4, 5, 14, 15, 19, 24(hint: one letter of the keyword is “E” and one “R” has the plaintext “T”. You can write a program to solve this if you have to.)

Chapter 3: 3, 5 (you only need to generate 8 bits instead of 32 bits. Also the first key bit is generated after the first stepping.), 11 (a, b, c) , 14, 23, 40 (this problem is an extra credit one, 10 points)

In addition:

(A1) What is a security model? Describe the security model with the following application. Suppose you are developing a multi-play online gambling system.

(A2) To design strong ciphers, what are the two security requirements and two design principles? Please explain them their meanings.

(A3) Draw a table to show the block size, key length, number of rounds for each of the following block ciphers: DES, 3DES, AES.