Secure Login: Passwordless Authentication

TL;DR

Instead of sending your password to the server, we’ll use a secure method where the server verifies you *have* the password without ever knowing it directly. This is done using hashing and salting.

How It Works

This guide explains how to implement a more secure login system. The core idea is that your password isn’t stored on the server in plain text, or even encrypted in a way the server can easily reverse. Instead, it’s transformed into a unique ‘hash’.

Step-by-Step Guide

1. Hashing Passwords: When a user creates an account:
   • The password is taken from the user.
   • A random ‘salt’ is generated (a string of characters). This makes it harder to crack passwords even if the database is compromised.
   • The salt and password are combined, then passed through a hashing function (like bcrypt or Argon2). This creates the hash.
   • Store the hash and salt in your database – never store the original password!
2. Verification During Login: When a user tries to log in:
   • The user enters their password.
   • Retrieve the salt associated with that username from the database.
   • Combine the entered password and the retrieved salt.
   • Hash this combination using the same hashing function used during registration.
   • Compare the newly generated hash to the stored hash in the database. If they match, the login is successful!

Example Code (PHP with bcrypt)

This shows a simplified example using PHP and the bcrypt extension. Important: This is for demonstration only; production code requires more robust error handling and security measures.

Registration

Login

Important Considerations

• Hashing Algorithm: Use strong hashing algorithms like bcrypt or Argon2. These are designed to be slow, making brute-force attacks more difficult.
• Salting: Always use a unique salt for each password.
• Database Security: Protect your database from unauthorized access.
• Rate Limiting: Implement rate limiting to prevent attackers from trying many passwords in a short period of time.
• Two-Factor Authentication (2FA): Consider adding 2FA for an extra layer of security.