Recall the online bid method discussed in Section 5.8.1. a. What property or properties of a secure hash function h does this scheme rely on to prevent cheating? b. Suppose that Charlie is certain...

Recall the online bid method discussed in Section 5.8.1.

a. What property or properties of a secure hash function h does this scheme rely on to prevent cheating?

b. Suppose that Charlie is certain that Alice and Bob will both submit bids between $10,000 and $20,000. Describe a forward search attack that Charlie can use to determine Alice's bid and Bob's bid from their respective hash values.

c. Is the attack in part b a practical security concern?

d. How can the bidding procedure be modified to prevent a forward search such as that in part b?