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VB app ideas needed...

Posted on 2004-03-26
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Hello all,

I need to come up with some ideas for a application. Here is the senario:

I have some PDFs that need to be distributed to some people in our company and we know these might get into the hands of the competition eventually, but we want to avoid this. These PDFs will be password protected

I need to prepare a app that will warehouse these PDFs and make it difficult for anyone to distribute them even if they were installed on their computer. Any ideas how this came be done effectively.

Thanks!
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Question by:KalluMama
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by:matt150279
ID: 10688644
You could write a passworded database program, which enabled you to email PDFs to people within the business, but only when authorisation has been granted.

ie there could be 1,2 however many people with authority to let people access these files, and only when they have clicked the button/marked the checkbox will the file be accesible and the password/PDF emailed to them.

You could also build something into Outlook that made the email with the pDF attachment time sensitive and impossible to forward, so that after three days of it being on the computer it is deleted, and for the person to read the PDF they have to seek authorisation through your software again.

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by:KalluMama
ID: 10690362
The PDFs will not be emailed, they are going to be sent out on CDs that is the way the bosses want it, but wanna make sure that the PDFs it is hard if not impossible to distribute them freely.

If the PDF were to be installed on the CD along with the app that controls access to them, how is it posssible to ensure that no one can sneak in from the back and check out the Pdfs without the right kind of permission.
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by:JohnBPrice
ID: 10690387
Well, you could host the pdf's on a web server so they never get installed, but no matter what you do, if they are simple pdf's, you can always do "Save As..." in Acrobat reader.  What you need to do is lock the PDF documents themselves so they cannot be saved or cannot be read off your network.  I think you can prevent saving or printing in Adobe Acrobat, see http://www.adobe.com/security/doccontrol.html.  This says that PDF also allows for customized security so you could write a gizmo to prevent the document from working off you network, or you can buy third party products that profess to do this (http://www.fileopen.com/publisher.html for one.)
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by:KalluMama
ID: 10690655
Thanks JohnBPrice, but this seems like a very expensive route...is there a simple way to hide the files in the directory? seurity is important but not at that price....

As far as the "Save As" question is concerned, i can look into disabling that...
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JohnBPrice earned 50 total points
ID: 10691564
Hmm, Simple and cheap for CD distribution right?  You can "hide" the files by setting the hidden and/or system flags, but that doesn't do much.  Anyone can turn on the "Show Hidden Files" feature in Windows.  

You could put the .pdf's into a password protected zip file, and provide an app that has the password embedded in it.  You could also try embedding the .pdfs directly in your app resources.

I think all CD's have a unique serial number, including CDRs.  The app could check the serial number on the CD perhaps?  I don't know how to do that, but a quick search of google turned up a number of hits.  That would restrict viewing to those who physically posess your CD, have CD pirating software, or want to do a lot of Alt-PrtScr and feed it to an OCR engine.  That'd meet my definition of hard, but not impossible to copy.  I don't believe there is an impossible.
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by:blostar
ID: 10700977
A password based system would probably be better than this.. just write a VB app to handle and encrypt the files as binary, then write a decoding program with a built in viewer for the pdf's ... fair enough it is not the simplest option, but it would certainly be secure.. just make sure that there are no 'temp' files left behind the application ie: load the file into memory ...

only my thoughts on this ....

i wrote a program a few years ago to securely store passwords in text files.. it involved heavy encryption that meant the file contained no readable text... when viewing the file it was only ever decrypted in RAM meaning that once the app did its 'clean up' there was little or no sighn of the original.... how simple or hard it would be to do this with a PDF i don't know though..
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