Introduction to Passlib

Passlib is a versatile Python library designed for handling passwords and other sensitive data. With support for over 30 different password hashing algorithms, it’s an essential tool for implementing secure password storage and authentication mechanisms in your applications. In this guide, we delve into some of the most useful APIs provided by Passlib, accompanied by comprehensive code snippets and examples.

Installing Passlib

pip install passlib

Basics: Using the CryptContext class

This class is the core of Passlib’s API for handling password hashes. It allows you to manage multiple algorithms and policies.

Creating a CryptContext

  from passlib.context import CryptContext
  
  pwd_context = CryptContext(
      schemes=["pbkdf2_sha256", "des_crypt"], 
      deprecated="auto")

Hashing a Password

  hash = pwd_context.hash("mysecretpassword")
  print(hash)

Verifying a Password

  is_valid = pwd_context.verify("mysecretpassword", hash)
  print(is_valid)  # True

Advanced Usage: Customizing Hash Schemes

Setting Options for Algorithms

  pwd_context = CryptContext(
      schemes=["pbkdf2_sha256"],
      pbkdf2_sha256__default_rounds=8000
  )

Using Passlib Hashes in Django

Passlib can be integrated into Django applications to manage password hashing and authentication seamlessly.

Integrating Passlib

  from passlib.hash import pbkdf2_sha256
  
  def set_password(raw_password):
      return pbkdf2_sha256.hash(raw_password)
  
  def check_password(raw_password, hashed_password):
      return pbkdf2_sha256.verify(raw_password, hashed_password)

Using in Django Models

  class User(models.Model):
      username = models.CharField(max_length=150, unique=True)
      password = models.CharField(max_length=128)
      
      def set_password(self, raw_password):
          self.password = set_password(raw_password)
      
      def check_password(self, raw_password):
          return check_password(raw_password, self.password)

Complete Flask App Example

Here is a complete Flask app example demonstrating how to use Passlib for password hashing:

  from flask import Flask, request, jsonify
  from passlib.context import CryptContext
  
  app = Flask(__name__)
  pwd_context = CryptContext(schemes=["pbkdf2_sha256"], deprecated="auto")
  
  users = {}
  
  @app.route('/signup', methods=['POST'])
  def signup():
      username, password = request.json["username"], request.json["password"]
      if username not in users:
          users[username] = pwd_context.hash(password)
          return jsonify({"msg": "User created successfully"}), 201
      return jsonify({"msg": "User already exists"}), 400
  
  @app.route('/login', methods=['POST'])
  def login():
      username, password = request.json["username"], request.json["password"]
      if username in users and pwd_context.verify(password, users[username]):
          return jsonify({"msg": "Logged in successfully"}), 200
      return jsonify({"msg": "Invalid credentials"}), 400
  
  if __name__ == '__main__':
      app.run(debug=True)

By leveraging Passlib in your Python applications, you can ensure that sensitive data like passwords are securely managed to protect against potential security threats.

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