How to encrypt password using Python Flask-Security using bcrypt?

Question

I'm trying to utlise the standard basic example in the docs for Flask-Security and have made it work except for the password being stored in plaintext.

I know this line:

user_datastore.create_user(email='[email protected]', password='password')

I could change to:

user_datastore.create_user(email='[email protected]', password=bcrypt.hashpw('password', bcrypt.gensalt()))

But I thought Flask-Security took care of the (double?) salted encryption and if I add the app.config['SECURITY_REGISTERABLE'] = True and go to /register the database this time IS encrypted correctly.

I know I am missing something simple but don't quite understand where..

from flask import Flask, render_template
from flask_sqlalchemy import SQLAlchemy
from flask_security import Security, SQLAlchemyUserDatastore, UserMixin, RoleMixin, login_required
import bcrypt

# Create app
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
app.config['SECRET_KEY'] = 'super-secret'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///login.db'
app.config['SECURITY_PASSWORD_HASH'] = 'bcrypt'
app.config['SECURITY_PASSWORD_SALT'] = b'$2b$12$wqKlYjmOfXPghx3FuC3Pu.'

# Create database connection object
db = SQLAlchemy(app)

# Define models
roles_users = db.Table('roles_users',
        db.Column('user_id', db.Integer(), db.ForeignKey('user.id')),
        db.Column('role_id', db.Integer(), db.ForeignKey('role.id')))

class Role(db.Model, RoleMixin):
    id = db.Column(db.Integer(), primary_key=True)
    name = db.Column(db.String(80), unique=True)
    description = db.Column(db.String(255))

class User(db.Model, UserMixin):
    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.String(255), unique=True)
    password = db.Column(db.String(255))
    active = db.Column(db.Boolean())
    confirmed_at = db.Column(db.DateTime())
    roles = db.relationship('Role', secondary=roles_users,
                            backref=db.backref('users', lazy='dynamic'))

# Setup Flask-Security
user_datastore = SQLAlchemyUserDatastore(db, User, Role)
security = Security(app, user_datastore)

# Create a user to test with
@app.before_first_request
def create_user():
    try:
        db.create_all()
        user_datastore.create_user(email='[email protected]', password='password')
        db.session.commit()
    except:
        db.session.rollback()
        print("User created already...")

# Views
@app.route('/')
@login_required
def home():
    return render_template('index.html')

if __name__ == '__main__':
    app.run()

Solution 1

Instead of storing the password you can use python's native decorators to store a hashed version of the password instead and make the password unreadable for security purposes, like this:

class User(db.Model, UserMixin):
    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.String(255), unique=True)
    password_hash = db.Column(db.String(128))

    @property
    def password(self):
        raise AttributeError('password not readable')
    @password.setter
    def password(self, password):
        self.password_hash = bcrypt.hashpw('password', bcrypt.gensalt()))
        # or whatever other hashing function you like.

You should add a verify password function inline with the bcrypt technolgy you implement:

    def verify_password(self, password)
        return some_check_hash_func(self.password_hash, password)

Then you can create a user with the usual:

User(email='[email protected]', password='abc')

and your Database should be populated with a hashed password_hash instead of a password attribute.

Solution 2

You're right, create_user() doesn't hash the password. It is a lower-level method. If you are able to use registerable.register_user() instead, then it will hash the password for you. But if you would like to use create_user() directly, then just encrypt the password before calling it:

from flask import request
from flask_security.utils import encrypt_password

@bp.route('/register/', methods=['GET', 'POST'])
@anonymous_user_required
def register():
    form = ExtendedRegistrationForm(request.form)

    if form.validate_on_submit():
        form_data = form.to_dict()
        form_data['password'] = encrypt_password(form_data['password'])
        user = security.datastore.create_user(**form_data)
        security.datastore.commit()

    # etc.

I wouldn't recommend overriding the password hashing on the User object, since Flask-Security uses the SECURITY_PASSWORD_HASH setting to store the password hashing algorithm. (It defaults to bcrypt, so you don't need to set this explicitly if you don't want to.) Flask-Security uses HMAC to salt the password, in addition to the SECURITY_PASSWORD_SALT which you provide, so just hashing the password using e.g. passlib with bcrypt won't result in a hash that Flask-Security will correctly match. You might be able to side-step this by cutting Flask-Security out of the loop and doing all password creation and comparison tasks yourself… but what's the point? You're using a security library, let it do security for you. They've already fixed the bugs you're bound to run into.