Password Hashing with Bcrypt in Flask

Introduction

Securing user passwords is a critical part of building any web application. Instead of storing passwords in plain text, hashing them makes it much harder for attackers to gain access to sensitive data. This tutorial explains how to implement password hashing in Flask using the Bcrypt library, a widely trusted hashing algorithm designed for password security.

What is Bcrypt?

Bcrypt is a password hashing function that incorporates salt and is designed to be computationally intensive, which helps defend against brute-force attacks. Its adaptive nature means you can increase the complexity over time as computing power grows, keeping your stored passwords secure for the long term.

Installing Flask-Bcrypt

To get started, install Flask-Bcrypt using pip:

pip install flask-bcrypt

Setting Up Flask and Bcrypt

Import Flask and Flask-Bcrypt, initialize the app, and set up the Bcrypt extension:

from flask import Flask, request, render_template
from flask_bcrypt import Bcrypt

app = Flask(__name__)
bcrypt = Bcrypt(app)

Hashing a Password

When a user registers or changes their password, hash it before saving to the database:

password = request.form['password']
hashed_password = bcrypt.generate_password_hash(password).decode('utf-8')

This generates a hashed version of the password which is safe to store.

Checking Passwords During Login

When a user logs in, compare their entered password against the stored hash like this:

is_correct = bcrypt.check_password_hash(hashed_password, entered_password)
if is_correct:
    # Allow login
else:
    # Deny access

Putting It All Together

By integrating these methods into your Flask app’s registration and login workflows, you ensure user passwords are never saved in plaintext and remain protected even if your database is compromised.

Conclusion

Utilizing Bcrypt for password hashing in Flask is an effective way to secure user credentials. This approach safeguards sensitive information and is a vital step toward building trustworthy web applications.

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