The protocol referred to in Problem 15.1 can be reduced from seven steps to five, having the following sequence:

1. A → B:

2. A → KDC:

3. KDC → B:

4. B → A:

5. A → B:

Show the message transmitted at each step.

Problem 15.1

We outlined the public-key scheme proposed in [WOO92a] for the distribution of secret keys. The revised version includes ID_A in steps 5 and 6.What attack, specifically, is countered by this revision?