In this paper (Provably Secure Password Authenticated Key Exchange Based on RLWE for the Post-Quantum World), author describe password authenticated key exchange scheme on page 9 and 10 (see Fig. 1 on page number 10).
I have following doubts in my mind
- How initially new user starts communication with the server. Whether there is any registration process for new user?
- How server gets the client password, as in the protocol client do not send any password. On the contrary, server verifies it as $\gamma$' = -H1(pwc) where pwc is client password. I think Server may ask for password from client during registration phase and then store it in its database but i am not sure.
- In Fig. 1 on page number 10, client send $<C,m>$ to server. Is 'C' is client's id or sid or something else. As author do not give any description of it.
- Similarly, S is in session key formation skc= H4(C,S,m,$\mu$,$\sigma$,$\gamma$') in Fig.1. Is S is server id or sid or something else?