1. The Simple Substitution Cipher is a major improvement on the Caesar Cipher.

a. In what different ways is it an improvement?

b. If a Simple Substitution Cipher is used (with an unknown key) and we intercept the ciphertext OXAO then which of the following four-letter words could be the plaintext: JOHN, SKID, SPAS, LOOT, PLOP, OSLO?

c. If a Simple Substitution Cipher is used (with an unknown key) and we intercept the ciphertext BRKKLK then what do we know about the plaintext?

d. Suppose that in the case of intercepting BRKKLK we also know that the plaintext is the name of a country. What is the plaintext?

e. What important lesson does the BRKKLK example illustrate?