<?php
/**
 * standalone class for Encryption
 * 
 * Features :
 * This class facilitates encoding data to pass between two can be used for
 * encoding & decoding for cookie value or url param.
 *  
 * @author sudhir vishwakarma <hide@address.com>
 * @copyright Sudhir Vishwakarma 
 * 
 * @version 0.1 27102008
 *
 */
class Encryption {
    /**
     *  Set any difficult Key for guessing
     *
     *  @access public
     */
    var $skey = "-_-donthackit-_-";
    /**
     *  This makes url or cookie value safe after encrypting any value
     *
     *  @access public
     */
    public  function safe_b64encode($string) {
        $data = base64_encode($string);
        $data = str_replace(array('+','/','='),array('-','_',''),$data);
        return $data;
    }
    /**
     *  This makes url or cookie value safe after decrypting any value
     *
     *  @access public
     */
    public function safe_b64decode($string) {
        $data = str_replace(array('-','_'),array('+','/'),$string);
        $mod4 = strlen($data) % 4;
        if ($mod4) {
            $data .= substr('====', $mod4);
        }
        return base64_decode($data);
    }
    /**
     *  mcrypt libreary required
     *
     *  @access public
     */
    public  function enc($value){
        if(!$value){return false;}
        $text = $value;
        $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
        $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
        $crypttext = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $this->skey, $text, MCRYPT_MODE_ECB, $iv);
        return trim($this->safe_b64encode($crypttext)); 
    }
    /**
     *  mcrypt libreary required
     *
     *  @access public
     */
    public function dec($value){
        if(!$value){return false;}
        $crypttext = $this->safe_b64decode($value); 
        $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
        $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
        $decrypttext = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $this->skey, $crypttext, MCRYPT_MODE_ECB, $iv);
        return trim($decrypttext);
    }
}
?>