Lescript is simplified concept of ACME client implementation especially for Let's encrypt service. It's goal is to have one easy to use PHP file without dependencies.
Use at your own risk.
See commented content of Lescript.php and example.php. Please rewrite files to fit your needs - purpose of this library is not to use as it is nor use it in production!
Support challenge only through webroot.
PHP 5.4.8 and up OpenSSL extension Curl extension
If you prefer more robust and clean library see excelent https://github.com/kelunik/acme
Because of implementation of Let's encrypt to Poste.io!