Password storage best practices in Flask - Mini Project: Build & Apply

Password Storage Best Practices with Flask

📖 Scenario: You are building a simple Flask web app that allows users to register with a username and password. To keep user passwords safe, you need to store them securely using best practices.

🎯 Goal: Build a Flask app that stores user passwords securely by hashing them before saving. You will create the user data structure, configure the hashing setup, hash passwords on registration, and complete the Flask route to handle user signup.

📋 What You'll Learn

Create a dictionary to store users with their hashed passwords

Set up a password hashing function using Werkzeug security

Hash the password before storing it in the users dictionary

Complete the Flask route to accept username and password and store securely

💡 Why This Matters

🌍 Real World

Web applications must never store plain passwords. Hashing passwords protects user data if the database is compromised.

💼 Career

Understanding secure password storage is essential for backend developers and anyone working on user authentication systems.

1

Create user data storage

Create a dictionary called users to store usernames and their hashed passwords. Initialize it as an empty dictionary.

Flask

# Create an empty dictionary called users
# Your code here

Hint

Use users = {} to create an empty dictionary.

2

Import and configure password hashing

Import generate_password_hash from werkzeug.security. This function will help hash passwords securely.

Flask

users = {}
# Import generate_password_hash from werkzeug.security
# Your code here

Hint

Use from werkzeug.security import generate_password_hash to import the function.

3

Hash password before storing

Write a function called register_user that takes username and password. Inside, hash the password using generate_password_hash(password) and store it in the users dictionary with the username as key.

Flask

users = {}
from werkzeug.security import generate_password_hash

# Define register_user function
# Your code here

Hint

Define a function that hashes the password and saves it in the users dictionary.

4

Complete Flask route for user registration

Create a Flask app with a route /register that accepts POST requests. Inside the route, get username and password from request.form, call register_user(username, password), and return a success message.

Flask

users = {}
from werkzeug.security import generate_password_hash
from flask import Flask, request

app = Flask(__name__)

def register_user(username, password):
    hashed = generate_password_hash(password)
    users[username] = hashed

# Create /register route to accept POST and register user
# Your code here

Hint

Use Flask route decorator and get form data from request.form. Call the register_user function and return a message.

Practice

1. Why should you never store plain text passwords directly in your Flask application's database?

easy

A. Because plain text passwords can be easily stolen if the database is compromised.

B. Because plain text passwords take up more space than hashed passwords.

C. Because Flask does not support storing plain text passwords.

D. Because hashed passwords are faster to compare than plain text passwords.

Solution

1. Step 1: Understand password security risks

   Storing plain text passwords means if someone hacks the database, they get all user passwords directly.

2. Step 2: Importance of hashing

   Hashing transforms passwords into unreadable strings, protecting user data even if the database leaks.

3. Final Answer:

   Because plain text passwords can be easily stolen if the database is compromised. -> Option A

4. Quick Check:

   Password safety = Avoid plain text storage [OK]

Hint: Never store passwords as plain text, always hash first [OK]

Common Mistakes:

• Thinking hashing is optional
• Believing plain text is safe if database is secure
• Confusing hashing with encryption

2. Which of the following is the correct way to hash a password using Werkzeug in Flask?

easy

A. hashed = make_password(password)

B. hashed = generate_password_hash(password)

C. hashed = password_hash(password)

D. hashed = hash_password(password)

Solution

1. Step 1: Recall Werkzeug's hashing function

   Werkzeug provides generate_password_hash to hash passwords securely.

2. Step 2: Identify correct function usage

   The correct function call is generate_password_hash(password), other options are invalid or non-existent.

3. Final Answer:

   hashed = generate_password_hash(password) -> Option B

4. Quick Check:

   Use generate_password_hash() to hash passwords [OK]

Hint: Use generate_password_hash() from Werkzeug to hash passwords [OK]

Common Mistakes:

• Using non-existent functions like hash_password
• Confusing hashing with encryption functions
• Trying to hash passwords manually

3. What will the following Flask code output if the password check is correct?

from werkzeug.security import generate_password_hash, check_password_hash
hashed = generate_password_hash('secret123')
result = check_password_hash(hashed, 'secret123')
print(result)

medium

A. False

B. secret123

C. Error

D. True

Solution

1. Step 1: Understand generate_password_hash output

   This function creates a hashed string from 'secret123'.

2. Step 2: Check password correctness with check_password_hash

   It compares the hashed password with the plain text 'secret123' and returns True if they match.

3. Final Answer:

   True -> Option D

4. Quick Check:

   check_password_hash returns True if passwords match [OK]

Hint: check_password_hash returns True when password matches hash [OK]

Common Mistakes:

• Expecting the original password as output
• Confusing True/False return values
• Assuming check_password_hash modifies the hash

4. Identify the error in this Flask password check code:

from werkzeug.security import generate_password_hash, check_password_hash
hashed = generate_password_hash('mypassword')
if check_password_hash('mypassword', hashed):
    print('Access granted')

medium

A. The hashed and plain password arguments are reversed in check_password_hash.

B. generate_password_hash should not be used for hashing passwords.

C. The print statement should be outside the if block.

D. There is no error; the code works correctly.

Solution

1. Step 1: Check argument order in check_password_hash

   The first argument must be the hashed password, second is the plain password.

2. Step 2: Identify the reversed arguments

   The code passes plain password first and hash second, causing a logic error.

3. Final Answer:

   The hashed and plain password arguments are reversed in check_password_hash. -> Option A

4. Quick Check:

   check_password_hash(hash, password) order matters [OK]

Hint: Pass hashed first, plain password second to check_password_hash [OK]

Common Mistakes:

• Swapping arguments in check_password_hash
• Using generate_password_hash incorrectly
• Ignoring function argument order

5. You want to securely store user passwords in your Flask app and verify them on login. Which approach follows best practices?

hard

A. Store plain passwords in the database and compare them directly on login.

B. Encrypt passwords with a reversible method and decrypt them on login to compare.

C. Hash passwords with generate_password_hash before storing, then verify with check_password_hash during login.

D. Store passwords as plain text but log them only during login attempts.

Solution

1. Step 1: Understand secure password storage

   Passwords must be hashed before storing to prevent exposure if database leaks.

2. Step 2: Verify passwords securely on login

   Use check_password_hash to compare the stored hash with the login password safely.

3. Final Answer:

   Hash passwords with generate_password_hash before storing, then verify with check_password_hash during login. -> Option C

4. Quick Check:

   Hash before store, verify with check_password_hash [OK]

Hint: Hash before store, verify with check_password_hash on login [OK]

Common Mistakes:

• Storing or logging plain passwords
• Using reversible encryption instead of hashing
• Comparing plain passwords directly