<?php
//source: http://stackoverflow.com/questions/2448256/php-mcrypt-encrypting-decrypting-file
class Encryption
{
    const CYPHER = MCRYPT_RIJNDAEL_256;
    const MODE   = MCRYPT_MODE_CBC;
    const KEY    = 'MyEncryptionKeyIsBetterThanYours';

    public function encrypt($plaintext)
    {
        $td = mcrypt_module_open(self::CYPHER, '', self::MODE, '');
        $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
        mcrypt_generic_init($td, self::KEY, $iv);
        $crypttext = mcrypt_generic($td, $plaintext);
        mcrypt_generic_deinit($td);
        return rawurlencode(base64_encode($iv.$crypttext));
    }

    public function decrypt($crypttext)
    {
        $crypttext = rawurldecode($crypttext);
        $crypttext = base64_decode($crypttext);
        $plaintext = '';
        $td        = mcrypt_module_open(self::CYPHER, '', self::MODE, '');
        $ivsize    = mcrypt_enc_get_iv_size($td);
        $iv        = substr($crypttext, 0, $ivsize);
        $crypttext = substr($crypttext, $ivsize);
        if ($iv)
        {
            mcrypt_generic_init($td, self::KEY, $iv);
            $plaintext = mdecrypt_generic($td, $crypttext);
        }
        return trim($plaintext);
    }
}

//source: http://stackoverflow.com/questions/2448256/php-mcrypt-encrypting-decrypting-file

?>