How to prevent the use of print screen key?

[Cyro [RPF-BR]]

I have an very odd needing.
I need to prevent any kind of copy or reproduction of the Front Panel.
Asking the technical support, they ask me to try preventing by using Event Structure, wich do not works since the key Print Screen can not be read by the Event Structure (and it apears to be the oly one key that can't be read).
Evend the Query Input Devices.vi can't read the Print Screen Key.
I supose that using ActiveX or DLL's I can do it, but I don't know how.
Any clue?

Thanks
Cyro

[Wiebe@CARYA]

"Cyro [RPF-BR]" <x@no.email> wrote in message news:1164318007383-445186@exchange.ni.com...
I have an very odd needing. I need to prevent any kind of copy or reproduction of the Front Panel.Asking the technical support, they ask me to try preventing by using Event Structure, wich do not works since the key Print Screen can not be read by the Event Structure (and it apears to be the oly one key that can't be read).Evend the Query Input Devices.vi can't read the Print Screen Key.I supose that using ActiveX or DLL's I can do it, but I don't know how.Any clue?ThanksCyro


Since nobody replied, I'll give it a try.


If you want users to prevent "stealing" a picture from your front panel, I would give up. Even if you get Windows to ignore print screen commands, users will still be able to get device DIB's with freeware programs. All is explained (with sample code) on the msdn:


http://msdn.microsoft.com/msdnmag/issues/05/11/CatWork/default.aspx


To prevent LabVIEW to respond to the print screen command, you'll have to hook the window proc. and filter out the WM_HOTKEY message. There are some vi's that can be used to hook the window proc (I think OpenG).


Regards,


Wiebe.

[Cyro [RPF-BR]]

Thanks a lot for the help.
I slove part of my problem cleaning the clipboard each 1 second.
About the freeware programs to take snapshoots, I think I can track the most populars and check if some of them are loaded. If any are loaded, the program will close automaticaly. I just have to learn how to access the list of loaded programs.
Any sugestion?
Thanks again and have nice hollydays!

[Marc_A]

Just out of curiosity, can you tell us what is on that panel that you don't want anyone to get a picture of?

Also, if someone really wanted to get an image of it, they will. Even if you somehow prevent screenshot programs (there are a lot of them) and the print screen button, someone could just use a camera.

[Will.D]

There is an NI 'toolkit' which handles interaction with the Windows API, which is nice, since that can be very annoying.  Here is a link to the download page.  These should be able to handle all of the stuff you're looking to do.

[AnalogKid2DigitalMan]

Someone could always take a picture of the monitor with a camera (oops- just read Marc's post). If there is information you don't want people to see, move it out of viewable bounds on the front panel or only allow visibility after a password entry.

Message Edited by AnalogKid2DigitalMan on 12-14-2006 09:10 AM

[rolfk]

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@Cyro [RPF-BR] wrote:
Thanks a lot for the help.
I slove part of my problem cleaning the clipboard each 1 second.
About the freeware programs to take snapshoots, I think I can track the most populars and check if some of them are loaded. If any are loaded, the program will close automaticaly. I just have to learn how to access the list of loaded programs.
Any sugestion?
Thanks again and have nice hollydays!

---

An application that messes with the clipboard without explicit user interaction has no right of existence on any self respecting user computer. Sorry!

Rolf Kalbermatter

[Enrique]

Can you tell us why? A homework? Security reasons?

[Cyro [RPF-BR]]

There are calibration documents. Certified calibrations.
The costumer can sometimes ask a Lab to show the certified of the standards used to calibrate their instruments.
When the costumer's company have a solid Quality Ensurance System they often make auditorships to prove this documents.
But in some cases, they can not do it (or don't want). So they ask copies of the standarts certified.
Unfortunaly, in my country, some bad intentioned companys adulterate the copies we send them. Avoiding spent more money with calibrations next year. (So their instruments messurements can be realy wrong, but are "certified" for use).
Then when an accident happen and an instrument calibrated/developed by my Lab is somehow linked with the accident they can trace all the documents to ferify if our services are connected with the accident or not. If some bad intentioned company adulterate our standards certified we can have a big problem. In 1996 we had a problem like that and we spent lots of time, work and money to prove our inocence.
To avoid all this problems we are developing a digital copy system and send it via CD to our costumers with expiration date and anti-copy systems.
When the program is loaded the costumer must to read and accept the terms of use and the program's functionality. If he don't... Well, he will be reproved at his auditorships.
The program was tested in real auditorships two times and the costumers really liked. It helps to convence their audithors their QES have no fails.
And now a governamental organization knows about this pilot project and is interested in use it for the realy same reason we are developing it.

(back to the problem)
Marc is right. If they want, they can. So my work is to difficult their wishes. Of course there is no 100% safe database or bank site. Always have a guy that know how to exploit it. Every thing a computer do, a computer can undo. But there is a limit of how much time you will spent with this thing versus how much money you will save. I'm searching this limit.

Will.D: Thanks a lot for the help! It will save time on learning how to use Windows's APIs (I'm phisics, not IT).
And thanks again to Wiebe to resurrect my post and give me a way to follow.


Best regards to all LV Fellows.

[rolfk]

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@Cyro [RPF-BR] wrote:
There are calibration documents. Certified calibrations.
The costumer can sometimes ask a Lab to show the certified of the standards used to calibrate their instruments.
When the costumer's company have a solid Quality Ensurance System they often make auditorships to prove this documents.
But in some cases, they can not do it (or don't want). So they ask copies of the standarts certified.
Unfortunaly, in my country, some bad intentioned companys adulterate the copies we send them. Avoiding spent more money with calibrations next year. (So their instruments messurements can be realy wrong, but are "certified" for use).

Best regards to all LV Fellows.

---

I think a better course of action here would be to develop a process that can track down all issued certificates at the moment when it is issued with all relevant information using some form of encryption and stores them in a way that is both virtually tamperproof and also certified itself to guarantee data consistency and reliability. So when there is an incident where someone shows a falsified certificate you can just point back at your database proofing that this certificate has never really been issued by your organization at all.

This keeps the sensitive steps of the procedure under your control. Of course certifying your system that you can't delete an issued certificate without any traces yourself will be not easy but in a good certificate system you will need to have something like that anyhow.

Then the customer can create screen copies of your certificates as much as he wants but it won't help them. Anyhow I think it a bad idea that the screen copy can not be distinguished from a real certificate at all. A digital certificate will be quite different for sure and if you really need to print out something from this certificate print it out directly to the printer (for instance by using the report generation toolkit as low cost solution or a more involved printing interface that you could license) instead of as screen dump. The actual resolution of the print will then show easily that it is just a screen dump instead of a real certificate and the digital certificate on disk will be the actual master anyhow and the fianl proof in cases of dispute.

One last idea if you want to keep the low cost solution system as it appears you are using now. Make the actual VI front panel that is printed out for a certificate different to the one you are showing to the user. Then after the user has viewed the certificate on screen and accepted to print it out call this other VI dynamically but keep it hidden, pass all the relevant data to it and let it create its front panel and then as last step make it print itself out either by automatic front panel printing or through some print VIs floating around on this NI site. 

Rolf Kalbermatter

Message Edited by rolfk on 12-15-2006 08:28 AM