PHP加密解密函数收藏

// 加密数据并写到cookie里
$cookie_data = $this -> encrypt("scutephp.com", $data);
                     
$cookie = array(
    'name'   => '$data',
    'value'  => $cookie_data,
    'expire' => $user_expire,
    'domain' => '',
    'path'   => '/',
    'prefix' => ''
);
$this->input->set_cookie($cookie);
     
// 加密
public function encrypt($key, $plain_text) {   
    $plain_text = trim($plain_text);   
    $iv = substr(md5($key), 0,mcrypt_get_iv_size (MCRYPT_CAST_256,MCRYPT_MODE_CFB));   
    $c_t = mcrypt_cfb (MCRYPT_CAST_256, $key, $plain_text, MCRYPT_ENCRYPT, $iv);   
    return trim(chop(base64_encode($c_t)));   
}

if( isset($_COOKIE['data']) )
{
    //用cookie给session赋值
    $_SESSION['data'] = decrypt("nowamagic", $_COOKIE['data']);
}
   
function decrypt($key, $c_t) {   
    $c_t = trim(chop(base64_decode($c_t)));   
    $iv = substr(md5($key), 0,mcrypt_get_iv_size (MCRYPT_CAST_256,MCRYPT_MODE_CFB));   
    $p_t = mcrypt_cfb (MCRYPT_CAST_256, $key, $c_t, MCRYPT_DECRYPT, $iv);   
    return trim(chop($p_t));   
}