An U2F authentication by hardware keys exercise

Hardware keys 🔐 also called FIDO security keys are yet another solution to verify the user who is trying to log-in.
An example of a key 🔑 is this one manufactured by Yubico

Training U2F authentication by hardware keys is the main purpose of this repo
and because of this, SOLID, "magic numbers" etc. are not the most important concern.
Obsolete in normal circumstances (in production) logs like console.log's, print's etc. will be used also.

It will include more independent sub-projects or tasks related to yubiKey U2F development.

Codes in this exercise are based on Yubico php-u2flib-server repo.
Some parts are copy-pased from their repo with slight modification (I do not own copyright on the original codes).

To learn more about U2F development, yubiKeys and things around FIDO, visit developers.yubico.com/U2F or FIDO Alliance website.

Apache, mySQL, PHP are required.

To run U2F authentication locally (localhost) SSL keys are required (https://).
Solution to create keys (or one of solutions) which met requirements on Linux with Apache2 (2.4.x) is like this:

1. Enable SSL a2enmod ssl
2. Go to /etc/apache2/
3. Create folder to keep keys, e.g. ssl_keys and go to this folder
4. Create key for one year with RSA 2048 (it's localhost so security is not cause for concern)
   openssl genrsa -out localhost.key 2048
openssl req -new -out localhost.csr -sha256 -key localhost.key
openssl x509 -req -in localhost.csr -days 365 -signkey localhost.key -out localhost.crt -outform PEM
5. localhost.crt has to be public (private key localhost.key should remain private 😉)
   chmod 644 localhost.crt
6. Go to /etc/apache2/sites-available, edit default-ssl.conf and change lines with SSLCertificateFile and SSLCertificateKeyFile into

   SSLCertificateFile    /etc/apache2/ssl_keys/localhost.crt
   SSLCertificateKeyFile  /etc/apache2/ssl_keys/localhost.key
   

7. It might be required to add an alias into default-ssl.conf like:

   Alias /alias/ "/home/path-to-account-directory/public_html/"
   <Directory "/home/path-to-account-directory/public_html/">
       # your settings, e.g.:
       Options Indexes FollowSymlinks MultiViews
       AllowOverride all
       Order allow,deny
       allow from all
   </Directory>
   

Another requirement is a local_settings.php file with database settings like e.g.:

<?php
$db = array(
	'hostname' => 'localhost',
	'username' => 'admin',
	'password' => 'password1',
	'database' => 'db',
);

To prepare mySQL database, mysql_scheme.sql has to be imported. To do this on Linux:

1. Create database, e.g. database_name
2. Type in Linux console: mysql -u root database_name < mysql_scheme.sql
3. Grant privileges for the user of database: GRANT ALL PRIVILEGES ON database_name.* TO 'username'@'hostname';

To run php version just type https://localhost/<path-to-Apache-server>/yubiKey_exercise/ in a browser.