If you're using Composer:
$ composer require alexsasharegan/crypto
Then require in the vendor autoloader:
<?php
require_once 'path/to/vendor/autoload.php';
To install from github:
$ git clone https://github.com/alexsasharegan/crypto_lib.git
Then require in the autoloader:
<?php
require_once 'path/to/Crypto_lib/Crypto_Autoloader.php';