This example demonstrates the two-factor authentication, where the second factor to authenticate is system generated key. This key is embedded in a user image using the technique of steganography. To pass 2 factor authentication the user needs load an image with embedded key.

You can explore live demo to check how it works.

• PHP 5.4+
• GDLib
• gettext support
• PHP PDO Extension
• Mysqli

• Copy files from /web - to your web folder
• Setup DB
• Write settings in /engine/config.php
• Make sure that the folder /uploads/2fa is writable
• If you're using Apache, make sure you activate the URL rewriting module,
• For Nginx servers use proper location, for example

    location /2FAuthSteganography/ {
        root   /var/www/yousite;
        index  index.html index.php;
        try_files $uri /2FAuthSteganography/index.php?$request_uri;
    }

2FAuth-Steganography uses LSB method to modify least significant bit of image to embed auth-key. Detailed description with example can be found section "Steganography in Depth" of this book.

2FAuth-Steganography has implementation of LSB with such conditions:

• png, jpg or gif images as container,
• binary string as a auth-key.