15.What would be the effect on public key cryptography if mathematicians discover an easy way of finding the prime factors of large numbers? Explain why.

16. In the Unites States, organizations sometimes use Social Security Number or a part of it as an authenticator. Is this a good or bad idea? Explain your answer.

17.Explain in detail why a public key embedded in a digital certificate is much harder to tamper with than the public key alone? (Hint: This question asks about the certificate, not about trusting a certificate authority.)

18.Distinguish between a vulnerability and an exploit.

19.What is the purpose of a key exchange algorithm? With what type of cryptosystem is such an algorithm needed?

20. Briefly describe how the techniques of public key cryptography can be used to implement a digital signature. Be sure you distinguish correctly the use of public and private keys.

21.Explain why using a computationally intensive (i.e. slow) hash algorithm is important when storing password data.

22.Distinguish between authentication and authorization.

23.What is the principle of least privilege?

24.What is a default deny policy? (This is also called a closed policy in places in the textbook.)

25.Explain the difference between symmetric key encryption and asymmetric (public) key encryption.