This question is about Kerberos Version 4 from Table 15.1. Give explanations for the following: (a) Explain what would be the disadvantage if the lifetime in the service-granting ticket was very long and what would be the disadvantage if the lifetime was very short. (b) Suppose V is a le server and C wants to get les from V . One purpose of sending EC;V in round (4) is that V can encrypt les using EC;V to mantain con dentiality. Suppose C does not care about the con dentiality of these les i.e. he does not care if BG is able to read these les. In this situation, the les do not need to be encrypted with EC;V . In this situation, does EC;V still need to be included in round (4)? Give a YES/NO answer and then brie y explain your answer. (c) Suppose BG captures (4) i.e. the communication from TGS to C. Will he be able to pose as C and get service from V ? Give a YES/NO answer and then brie y explain your answer.