How to protect Python source from modification

[Bryan Olson]

Steve M wrote:
[...]
 > 1. Based on your description, don't trust the client. Therefore,
 > "security", whatever that amounts to, basically has to happen on the
 > server.

That's the right answer. Trying to enforce security within your
software running the client machine does not work. Forget the
advice about shipping .py's or packaging the client in some way.

 > The server should be designed with the expectation that any
 > input is possible, from slightly tweaked variants of the normal
 > messages to a robotic client that spews the most horrible ill-formed
 > junk frequently and in large volumes. It is the server's job to decide
 > what it should do. For example, consider a website that has a form for
 > users to fill out. The form has javascript, which executes on the
 > client, that helps to validate the data by refusing to submit the form
 > unless the user has filled in required fields, etc. This is client-side
 > validation (analagous to authentication). It is trivial for an attacker
 > to force the form to submit without filling in required fields. Now if
 > the server didn't bother to do its own validation but just inserted a
 > new record into the database with whatever came in from the form
 > submission, on the assumption that the client-side validation was
 > sufficient, this would constitute a serious flaw. (If you wonder then
 > why bother putting in client-side validation at all - two reasons are
 > that it enhances the user experience and that it reduces the average
 > load on the server.)

Good advice.


-- 
--Bryan