1. Can one-time pad be reused? Why or why not? One common (traditional) approach was to "generate" a one-time pad by using passages from books. Though there need not be any repeats in the key, this method of encryption can still be broken. How?

2. entropy: source returns the output of an 8-face unfair die:
	1/8, 1/8, 1/16, 1/16, 1/4, 1/4, 1/16, 1/16
   a). compute entropy
   b). compute entropy for a fair 8-face die, and compare the result with a). 	  
   c). which value is higher and why?

3. chapter 10, Ex 13

4. chapter 10, Ex 20

5. chapter 10, Ex 21

6. In RSA, public key is e=31 and n=3599, what's the private key d= ?

7. (Extra Credit) Evaluate the following encryption methods using Shannon's standards
-substitution cipher
-transposition cipher
-Vernam cipher
-DES
-AES
-RSA