Support password verification without sending the password from client to server about argon2-cffi HOT 5 CLOSED

I'm not sure I 100% understood, so just to double-check:

You'd like that the server sends the client a salt (presumably the salt that it added to its own password) and the client returns an argon2 hash with said salt and the server can just compare its own hash with the one the client sent? 🤔

from argon2-cffi.

No, I would like that the client will have a salt that is never shared with the server.
so the client won't have to send the actual password to the server, but will use a constant argon2 hash instead.

This is the flow I have in my mind
Client code:

def get_temporary_token_from_server(user_name, user_password):
    ph = PasswordHasher(salt=os.environ.get("CLIENT_SALT")
    argon2_hash = ph.hash(user_password)
    token_from_server = server.get_token(user_name=user_name, password_hash=argon2_hash)

Server code:

def verify_password_hash(user_name, hash_from_client):
    user = get_user(user_name) # In the DB we store for each user argon2_hash and a unique random salt)
    user_hash_to_verify = concat(hash_from_client + user.user_salt)

    ph = PasswordHasher()
    # here we verify that the user.password_hash is a valid argon2 hash for user_hash_to_verify which is a constant string we can create by concating the constant argon2_hash sent via the client and the salt kept for this user in the server DB
    ph.verify(user.password_hash, user_hash_to_verify)

• the client will use a constant salt stored securely and unavailable to the server (this salt should be generated with secure random function)
• client salt is not being sent to the server
• the server will never know the user actual password
• the server may keep a salt for each user that the client isn't aware of.

from argon2-cffi.

I presume #153 would fix your problem?

from argon2-cffi.

yes, thanks 👍

from argon2-cffi.

23.1.0 is on PyPI

from argon2-cffi.