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Topic: FDF Security and Usablity Concerns...Please Help
Conf: (P-PDF) Developers, Msg: 103245
From: mike_diamond1
Date: 1/6/2004 02:41 AM

I am using the FDF toolkit to populate online pdf forms that contain very sensitive data. The forms are available on a government Intranet. I have users on Acrobat 5.0 (Reader and Full) and 6.0 (Reader and Professional). Our fdf documents are loaded through a "#FDF=mypath.fdf" extension to a pdf url.

The problem I am having is that cached FDF's keep reloading with subsequent calls to the pdf. My average user may reload the same pdf form with different fdf data 30 or 40 times a day. Yes, the cached data can be cleared with a Reset(). But there are problems with this workaround. And these problems get worse the more a user reloads a form with new fdf data.

For one, the initial appearance of all this cached data, even if then wiped out with a reload, is a security concern. If the browser or Reader plugin freezes at this point sensitive data would exposed.

Second, since the forms have heavy calculations, the fluttering calculator works overtime. I have tried turning the calculation property off during the before import of FDF javascript (set in the FDF) and then on during the after import of FDF javascript (set in the fdf). But as each fdf loads from cache, the calcuation is also turned continuously on and off, and the fluttering continues.

(To illustrate these problems, put an alert in your javascript that executes on import of the fdf. The pause caused by the alert will show you the load of each cached fdf into your pdf. In testing, I used the alert to display the primary key and timestamp of each dataset that gets reimported from the cache and was shocked at how much sensitive data was reentering the form before being cleared)

What to do? I have tried deselecting the Keep Forms Data Temporarily Available on Disk checkbox in Acrobat 6.0. As far as I can tell, deselecting this option does not prohibit cached fdfs from reloading. I have the same problems with this checkbox deselected.

My current workaround is to pass a random variable in the pdf url, such as: x=174687. This seems to fool the pdf into thinking this is a new document and ignoring cached data. But, in doing so, I am forced to reload the pdf every time as well, hence losing the benefit of separating form from content in terms of download times.

Has anyone figured out a better solution? Thanks in advance for any responses

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