You are a painter and have an Internet store where you sell your paintings directly to the public. You would like customers to pay for their purchases with credit cards, and wish to ensure that these electronic transactions are secure.
Assume that Mary wants to purchase your recent painting of the Cornell Uris Library.
Answer the following questions.
1. How can you ensure that the user who is purchasing the painting is really Mary?
2. Explain how SSL ensures that the communication of the credit card number is secure. What is the role of a certification authority in this case?
3. Assume that you would like Mary to be able to verify that all your email messages are really sent from you. How can you authenticate your messages without encrypting the actual text?
4. Assume that your customers can also negotiate the price of certain paintings and assume that Mary wants to negotiate the price of your painting of the Madison Terrace. You would like the text of this communication to be private between you and Mary. Explain the advantages and disadvantages of different methods of encrypting your communication with Mary.