verifying password with hash on the backend to make sure we don't decrypt garbage and also to make sure that everything is encrypted with same password/key

generate-password.py

@@ -2,7 +2,8 @@
 
 import getpass
 
-import bcrypt  # pip install bcrypt
+import scrypt  # pip install scrypt
+import binascii
 
 password1 = getpass.getpass()
 
@@ -11,9 +12,17 @@ print('Repeat the same password:')
 password2 = getpass.getpass()
 
 if password1 == password2:
-    salt = bcrypt.gensalt()
+    # salt is constant
+    salt = "dc73b57736511340f132e4b5521d178afa6311c45e0c25e6a9339038507852a6"
 
-    print('Generated hash:')
-    print(bcrypt.hashpw(password1, salt))
+    hashed = scrypt.hash(password=password1,
+                           salt=salt,
+                           N=16384,
+                           r=16,
+                           p=1,
+                           buflen=32)
+
+    print('Generated password hash:')
+    print(binascii.hexlify(hashed))
 else:
     print('Entered passwords are not identical!')

src/app.py

@@ -1,6 +1,7 @@
 import os
 
-import bcrypt
+import binascii
+import scrypt
 import configparser
 from flask import Flask, request, send_from_directory
 from flask import render_template, redirect
@@ -11,6 +12,7 @@ from notes_api import notes_api
 from sql import connect
 from tree_api import tree_api
 from notes_move_api import notes_move_api
+from password_api import password_api
 
 config = configparser.ConfigParser()
 config.read('config.ini')
@@ -20,6 +22,7 @@ app.secret_key = config['Security']['flaskSecretKey']
 app.register_blueprint(tree_api)
 app.register_blueprint(notes_api)
 app.register_blueprint(notes_move_api)
+app.register_blueprint(password_api)
 
 class User(UserMixin):
     pass
@@ -53,11 +56,26 @@ connect(documentPath)
 
 hashedPassword = config['Login']['password-hash'].encode('utf-8')
 
+
+def verify_password(hex_hashed_password, guessed_password):
+    hashed_password = binascii.unhexlify(hex_hashed_password)
+
+    salt = "dc73b57736511340f132e4b5521d178afa6311c45e0c25e6a9339038507852a6"
+
+    hashed = scrypt.hash(password=guessed_password,
+                         salt=salt,
+                         N=16384,
+                         r=16,
+                         p=1,
+                         buflen=32)
+
+    return hashed == hashed_password
+
 @app.route('/login', methods=['POST'])
 def login_post():
     inputPassword = request.form['password'].encode('utf-8')
 
-    if request.form['username'] == user.id and bcrypt.hashpw(inputPassword, hashedPassword) == hashedPassword:
+    if request.form['username'] == user.id and verify_password(hashedPassword, inputPassword):
         rememberMe = True if 'remember-me' in request.form else False
 
         login_user(user, remember=rememberMe)

src/password_api.py

@@ -0,0 +1,28 @@
+from flask import Blueprint, jsonify, request
+from flask_login import login_required
+import hashlib
+import configparser
+import binascii
+
+password_api = Blueprint('password_api', __name__)
+
+@password_api.route('/password/verify', methods = ['POST'])
+@login_required
+def verifyPassword():
+    req = request.get_json(force=True)
+
+    config = configparser.ConfigParser()
+    config.read('config.ini')
+
+    hashedPassword = config['Login']['password-hash'].encode('utf-8')
+    hashedPasswordBytes = binascii.unhexlify(hashedPassword)
+    hashedPasswordSha = hashlib.sha256(hashedPasswordBytes).hexdigest()
+
+    print(req['password'])
+    print(hashedPasswordSha)
+
+    isValid = req['password'] == hashedPasswordSha
+
+    return jsonify({
+        'valid': isValid
+    })

static/js/note.js

@@ -204,9 +204,7 @@ function addRecentNote(noteTreeId, noteContentId) {
 function deriveEncryptionKey(password) {
     // why this is done is explained here: https://github.com/ricmoo/scrypt-js - "Encoding notes"
     const normalizedPassword = password.normalize('NFKC');
-    // use password as a base for salt (which is itself salted with constant) so that we don't need to store it
-    // this means everything is encrypted with the same salt.
-    const salt = sha256("Jg&)hZ$" + normalizedPassword + "*P7j.");
+    const salt = "dc73b57736511340f132e4b5521d178afa6311c45e0c25e6a9339038507852a6";
 
     const passwordBuffer = new buffer.SlowBuffer(normalizedPassword);
     const saltBuffer = new buffer.SlowBuffer(salt);
@@ -228,8 +226,25 @@ function deriveEncryptionKey(password) {
             else if (key) {
                 console.log("Computation took " + (new Date().getTime() - startedDate.getTime()) + "ms");
 
+                $.ajax({
+                    url: baseUrl + 'password/verify',
+                    type: 'POST',
+                    data: JSON.stringify({
+                        password: sha256(key)
+                    }),
+                    contentType: "application/json",
+                    success: function (result) {
+                        if (result.valid) {
                             resolve(key);
                         }
+                        else {
+                            alert("Wrong password");
+
+                            reject();
+                        }
+                    }
+                });
+            }
             else {
                 // update UI with progress complete
             }