Re: Referer (was Patches for wwwboard.pl)

[davids () WEBMASTER COM (David Schwartz)]

        You should also be including a timestamp and an originator IP in the hash
function. Otherwise you are vulnerable to interception and replay attacks.
If you're going to do it, you might as well do it right.

        DS

> Even though I wrote this, it turns out that this isn't the best way to
> compute a message authentication code (MAC).  A more secure technique
> is this:
>
>  $hash=MD5->hexhash($secret . MD5->hexhash("$secret @untamperable
> @consistency"))
>
> I explain the problems with the original scheme in the October issue
> of Web Techniques.
>
> Lincoln
>
> --
> ========================================================================
> Lincoln D. Stein                           Cold Spring Harbor Laboratory
> lstein () cshl org                                   Cold Spring Harbor, NY
> ========================================================================