Welcome to the exciting world of securing your Ruby on Rails applications! In this section, we'll focus on an essential aspect of application security — user authentication using Bcrypt for password hashing. If you've been following along, you already have a basic understanding of how Ruby on Rails works. Now it's time to add an important security layer to your applications.

In this lesson, you will delve into the process of setting up user authentication using Bcrypt in a Ruby on Rails application. Specifically, you will learn how to create a user registration and login system. We'll cover how to securely store passwords using password hashing, which is a secure way to keep user data protected. You'll also gain hands-on experience writing migration files, implementing authentication logic in controllers, and setting up the appropriate view templates.

Here are some of the components you'll work with, specifically addressing the use of Bcrypt:

• Using has_secure_password in the User model for password handling.

  Ruby
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  1class User < ApplicationRecord
  2  has_secure_password
  3end

  The has_secure_password method is an ActiveRecord feature that utilizes Bcrypt under the hood. It adds functionalities that allow you to store a securely hashed password_digest attribute in the database. When you use has_secure_password, two virtual attributes are added to your model: password and password_confirmation, alongside the authenticate method. Bcrypt will hash these passwords and store them securely, protecting them from being easily decoded even if the database is compromised.

• Setting up a basic authentication flow in the AuthenticationController.

  Ruby
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  1class AuthenticationController < ApplicationController
  2  def register
  3    @user = User.new
  4  end
  5
  6  def create
  7    @user = User.new(user_params)
  8    if @user.save
  9      redirect_to login_path
  10    else
  11      render :register
  12    end
  13  end
  14
  15  # ... more actions ...
  16end

  In the create action, user details including the password (which will be hashed by Bcrypt) are saved to the database. If saving is successful (@user.save returns true), the user is redirected to the login path; otherwise, the registration form is re-rendered. The secure handling of the password in this flow bolsters your application's defenses against potential data breaches.

Understanding how to implement user authentication is critical for any web developer. It ensures that only authorized users can access certain parts of your application, protecting sensitive data from unauthorized access. Bcrypt helps you securely manage user passwords by hashing them before storing them in the database. This provides an extra layer of security, making it difficult for attackers to retrieve original passwords even if they gain access to your database.

You're enhancing both the functionality and the security of your application, making it more robust and trustworthy. As we embark on this section, remember that this knowledge is not only about building secure applications but also about creating a seamless user experience. Secure authentication is the foundation that builds user trust in your application.

Let's get ready to dive into the practice section and explore these concepts together!