1.

a. Convert the decimal number 1022 to a binary form and hexadecimal form.

b. How many English characters (ASCII) can 1 Gigabyte hard disk save exactly?

2. Keys pace and modulo operations.

a. How long does it take (in second) to guarantee to find the correct key if you know a key length is 10 bits? Assume you need one second to verify the correctness of each key.

b. List five possible numbers for x for the equation x 1 mod 7

3. Assume the rules for generating a password are defined as follows:

a. Has exactly 4 characters long.

b. Must have one digit

c. Must have one up case letter

d. Must have one of these special characters ~!@#$%^&*()_+

e. Must have one low case letter

How many possible passwords we can generate? You need to write the formula.

4. Assume you and your friends have agreed to use the following table to encrypt and decrypt a message. In the table, the letters of the alphabet are encoded as numbers.

Encrypt the message "UB" using Caesar cipher. Key=5.

Use the math formula to express the encrypting and decryption process.

5. Substitution cipher

a. Create a table for substitution cipher

b. Encrypt the message "ub" using your substitution cipher.

6. If you want to brute-force attack Caesar cipher and substitution cipher, i.e., decipher the message that encrypted byquestion 4 and 5, how many different passwords you have to try to guarantee that you will break the ciphertext, respectively? Only formula is needed. Don't need to compute the results.

a. brute-force attack Caesar cipher

b. brute-force attack substitution cipher

7. Encrypt the message "UB" using a stream cipher. Key='a'. Show steps.

8. Provide one example to demonstrate the concept of confusion and diffusion, respectivly?

9. List the stpes of F-function of DES and explain each of them in details.