Question:

(a) What is a script kiddie? Is it a significant security threat, and why?

(b) Assume that UNIX uses the user login name in lieu of the traditional salt, what is the effect on the security of the password?

(c) Explain the rationale behind the fact that many banks and credit card companies allow their customers to access their accounts from ATM machines using only 4 digits personal identification numbers (PIN).

(d) Consider Alice and Bob communicating. Compare the following two possible messages M1 and M2 sent by Alice. K is the secret key shared between Alice and Bob and K {m} denotes m encrypted using K.

M1: I'm Alice, K{timestamp}
M2: I'm Alice, timestamp, hash{K, timestamp}

(i) What three security features are provided by M1 and M2?

(ii) Which message M1 or M2 is more secure and why?