Use best practices for password hashing in webservice

solvable/Dockerfile

@@ -2,7 +2,8 @@ FROM eu.gcr.io/avatao-challengestore/tutorial-framework
 
 # Install webservice dependencies
 RUN pip3 install Flask==1.0        \
-                 SQLAlchemy==1.2.7
+                 SQLAlchemy==1.2.7 \
+                 passlib==1.7.1
 
 # Define variables to use later
 ENV TFW_SERVER_DIR="/srv/.tfw"                      \

solvable/src/webservice/model.py

@@ -1,6 +1,7 @@
 from sqlalchemy import Column, Integer, String, create_engine
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import scoped_session, sessionmaker
+from passlib.hash import pbkdf2_sha256
 
 engine = create_engine('sqlite:///db.db', convert_unicode=True)
 db_session = scoped_session(sessionmaker(autocommit=False,
@@ -20,3 +21,13 @@ class User(Base):
 
 def init_db():
     Base.metadata.create_all(bind=engine)
+
+
+class PasswordHasher:
+    @staticmethod
+    def hash(password):
+        return pbkdf2_sha256.hash(password)
+
+    @staticmethod
+    def verify(password, hash):
+        return pbkdf2_sha256.verify(password, hash)

solvable/src/webservice/server.py

@@ -1,9 +1,8 @@
 from os import urandom, getenv
-from hashlib import sha512
 
 from flask import Flask, render_template, request, session, url_for
 
-from model import db_session, init_db, User
+from model import db_session, init_db, User, PasswordHasher
 
 BASEURL = getenv('BASEURL', '')
 init_db()
@@ -21,18 +20,12 @@ def remove_db_session(exception=None):
     db_session.remove()
 
 
-def hash_password(password):
-    salt = 'justsomerandombytes'.encode()
-    return sha512(password.encode()+salt).hexdigest()
-
-
 @app.route('/', methods=['GET', 'POST'])
 def index():
     if request.method == 'POST':
-        user = User.query.filter(User.username == request.form['username'], 
-                                 User.passwordhash == hash_password(request.form['password'])).first()
+        user = User.query.filter(User.username == request.form['username']).first()
 
-        if not user:
+        if not user or not PasswordHasher.verify(request.form['password'], user.passwordhash):
             return render_template('login.html', alert='Invalid credentials!')
         else:
             session['logged_in'] = True
@@ -53,10 +46,11 @@ def register():
             return render_template('register.html', alert='Username already in use.')
 
         db_session().add(User(username=request.form['username'],
-                              passwordhash=hash_password(request.form['password'])))
+                              passwordhash=PasswordHasher.hash(request.form['password'])))
         db_session().commit()
 
         return render_template('login.html', success='Account "{}" successfully registered. You can log in now!'.format(request.form['username']))
+
     return render_template('register.html')