<?php

    /**
    * Implements the encryption for Market Rader
    *
    */
    class MarketRadarEncryption
    {
        /**
        * Holds the given key, first transformed to md5 and then converted to binary
        * @var string
        */
        private $key    = null;

        /**
        * Holds the iv that will be generated from the given key
        * @var string
        */
        private $iv     = null;

        /**
        * The handle to the mcrypt module
        *
        * @var mixed
        */
        private $moduleHandle     = null;



        /**
        * Contructor
        *
        * @param string $key - The preshared key
        *
        * @return MarketRadarEncryption
        *
        */
        public function __construct($key)
        {
            $this->key = $this->hex2bin(md5($key));

            $this->createIvBytes();
        }



        /**
        * Generates the iv out of the preshared key
        *
        * @return   string
        *
        */
        private function createIvBytes()
        {
            $this->iv = base64_decode("HeY8YU0ykRqc9gB7Qp1+kQ==");
        }



        /**
        * Encrypt the given string, care about base64 encoding and other needed stuff
        *
        * @param    string     $str
        *
        * @return   string
        *
        */
        public function encryptString($str)
        {
            if ($str === '') {
                return '';
            }

            $method = 'AES-128-CFB8';
            $encrypted = openssl_encrypt($str, $method, $this->key, OPENSSL_RAW_DATA, $this->iv);

            return str_replace(array('+', '/'), array('-', '_'), base64_encode($encrypted));
        }


        /**
        * Transform hex to binary data
        *
        * @param    string      $hexdata
        *
        * @return   string
        *
        */
        private function hex2bin($hexdata)
        {
            $bindata = '';

            for ($i = 0; $i < strlen($hexdata); $i += 2)
                $bindata .= chr(hexdec(substr($hexdata, $i, 2)));

            return $bindata;
        }
    }