$2.$ The chart below shows an authentication protocol, followed by data exchange, followed by disconnection. Only an initial part of the authentication protocol is shown; here, pw is A$$s password, J is a key derived from pw$,$ and L is a high$-$quality key. Assume an attacker that can $(1)$ eavesdrop messages and $(2)$ intercept and spoof messages sent by A $($but not those sent by B$).$ Complete the authentication protocol $($i$.$e$.,$ Supply the part indicated by the $**....**)$ so that in spite of this attacker