Suppose we are using a three-message mutual authentication protocol, and Alice initiates contact with Bob. Suppose we wish Bob to be a stateless server, and therefore it is inconvenient to require him to remember the challenge he sent to Alice.Lets modify the protocol so that Bob (still stateless) sends both a challenge, and a challenge encrypted with a key K_Bob that only he knows.Is this protocol Secure?

AliceI'm AliceBob

AliceR,K_Bob{R}Bob

AliceK_Bob{R},K_Alice_Bob{R}Bob