Encode and decode something

$data ='Demax';

$key ='kH961H3=#IqvE`gD8I0@dQEhJ6wMh2';


function encode_data($data ){
     return base64_encode( mcrypt_encrypt(MCRYPT_RIJNDAEL_256 , md5( $key), $data , MCRYPT_MODE_CBC, md5( md5($key ))));
}

function decode_data($data ){
     return rtrim( mcrypt_decrypt(MCRYPT_RIJNDAEL_256 , md5( $key), base64_decode( $data), MCRYPT_MODE_CBC , md5( md5($key ))), "\0" );
}



$encoded =encode_data( $data);

$decoded =decode_data( $encoded);