Regarding point 1, you can combine 'challenge response' with diffie helman to Have the server side not know the password And be secure against replay attacks

Regarding point 1, you can combine 'challenge response' with diffie helman to Have the server side not know the password And be secure against replay attacks given attacker access to plain text. The scheme is something like: Setup Server generates key (x, xG) where G is some elliptic curve base point. It stores x and sends xG to the client. The client computes y = H(password) and sends yG to the server. The server stores the shared secret. x (yG) Authentication: Server generates nonce r and sends r xG. Client computes y = H(password) and responds with y r xG Server verifies that the response equals r (x yG). End In this protocol, an attacker with access to plain text, even during setup, still can't do anything. This method is weak against MitM, but that can be solved on auth by doing a fully ephemeral diffie helman there. I concocted this scheme on like 10 minutes, so there might be mistakes, and it os probably suboptimal.