Re: Prevent caching of pdf files

> Currently on a secure Internet application we use the "Cache-Control: No
> Cache" header to prevent information from caching on client machines.  We
> would like to begin to provide pdf files via our application; however,
> there is a known issue with accessing pdf files with IE 6.0 sp1 when the
> no-cache header is used.  (Please refer to
> http://support.microsoft.com/default.aspx?scid=kb;en-us;812935
> for details.)  As we have no control over the client machines accessing
> our application, is there another way to prevent pdf files from being
> automatically stored on the clients without using the no-cache header?
>
> Thanks in advance,
> -Brett

This is quite a good question.

The most obvious one: Serve the files over HTTPS, this prevents caching of
files in virtually all browsers. Which of course according to the MS link
won't work unless people patch (unlikely).

Using an ActiveX control to restrict what a user can do (Microsoft for
example used to do this with your online MCSE transcripts, you could view,
and print, but not save the page). I don't know how well this would work for
a "non-HTML" type document.

And the only other things that comes to mind is some sort of content
management/DRM system, but those tend to be expensive and require
installation of client software.

Kurt Seifried, kurt@xxxxxxxxxxxx
A15B BEE5 B391 B9AD B0EF
AEB0 AD63 0B4E AD56 E574
http://seifried.org/security/


----- Original Message ----- 
From: "bsec" <bsec@xxxxxxxxx>
To: <SECPROG@xxxxxxxxxxxxxxxxx>
Sent: Friday, December 05, 2003 3:33 PM
Subject: Prevent caching of pdf files


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