Version 5 A n Alice {n Kabj PUBPRA Bob KAB denotes a session key Now only Alice and Bob can know the session key KAB Question:What is wrong with this authentication protocol? -Authentication-=mutual identity verification session key establishment 一 Bob authenticates Alice,but Alice did not authenticate Bob. -How to fix this problem? 1010 Version 5  Now only Alice and Bob can know the session key KAB.  Question: What is wrong with this authentication protocol? ─ Authentication= mutual identity verification + session key establishment ─ Bob authenticates Alice, but Alice did not authenticate Bob. ─ How to fix this problem? Alice Bob A n {{n, Kab}PUB}PRA KAB denotes a session key