hashnig passwords with argon2_cffi

Question

I am trying to understand how should I use argon2_cffi to store hashed passwords in my database.

Specifically, I am using this code to write the hashed password into my PostgreSQL table.

from argon2 import PasswordHasher

ph = PasswordHasher()

new_user = User(
    name=POST.get('name', 'default_value'),
    fullname=POST.get('fullname', 'default_value'),
    nickname=POST.get('nickname', 'default_value'),
    hashed_password=ph.hash(POST.get('password', 'default_value')))
session.add(new_user)

However, this produces a different password everytime the user inserts a password in my form, although the inserted text is the same.

Of course, I know this is he correct behaviour, but what should I do in order to verify that a given registered user has inserted the right password if I cannot produce the same hash?

Answer 1

Sorry, found out myself in the docs...

import argon2

ph = argon2.PasswordHasher()
def login(db, user, password):
    hash = db.get_password_hash_for_user(user)

    # Verify password, raises exception if wrong.
    ph.verify(hash, password)

    # Now that we have the cleartext password,
    # check the hash's parameters and if outdated,
    # rehash the user's password in the database.
    if ph.check_needs_rehash(hash):
        db.set_password_hash_for_user(user, ph.hash(password))