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savail

encrypting images .png with DirectX?

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Hey,
Is there any simple way to encrypt images (.png) with DirectX? If not could you recommend any good ways to encrypt them and describe how the image encryption works? I even don't know how to start :|. Would be very grateful for any advice.

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Short and blunt answer: if your game is able to decrypt the image, then anyone who installs your game will also be able to decrypt them, making it a waste of time...

To give a proper answer, we'd need to know -- why do you want to encrypt these images?

If you just want to make it difficult for people to mess with your game's content, then just put them in a ZIP file, rename the file to something other than ZIP, and use something like physfs to read them into your game.

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Nope, DirectX doesn't have any sort of encryption libraries.

Why do you want to do this? If it's to protect your assets, don't bother - if your game loads the images at any point, anyone with the simplest of tools can view them. Just run the game through PIX and you can view all of the textures, models, shaders and other assets it loads or creates.

EDIT: Ninja'd

EDIT #2: If you want some very basic encryption, just use a hex editor and delete the first 8 bytes of the file ([url="http://en.wikipedia.org/wiki/Portable_Network_Graphics#File_header"]The PNG file header[/url], which is always the same). Then when you want to load the image, load it into a memory buffer and prepend the 8 byte header. That'll stop the file being opened in most image editors, and from looking at the file in a text editor it won't be obvious what it is. But that won't help you against PIX or any number of other tools.

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I see, thanks a lot for answer! I wanted to encrypt images just to prevent stealing them etc but if it's not worth my effort I thought maybe attaching images as resources would be a good idea? Or it may be considered as a virus or sth like this?

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[quote name='savail' timestamp='1310211166' post='4833053']
I see, thanks a lot for answer! I wanted to encrypt images just to prevent stealing them etc but if it's not worth my effort I thought maybe attaching images as resources would be a good idea? Or it may be considered as a virus or sth like this?
[/quote]That won't really help either, you can get tools which will extract resources from an EXE or DLL, and someone could still use PIX or something similar to extract them.

Generally, it's just best to do whatever is easiest to do for you.

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I see, Thanks a lot for sharing such a knowledge with me! It's really important for me to know what dangers may I experience while protecting my resources so I really know what is helpful and what isn't. Thanks again.
Edit: I have got one more question: So how do great game developer firms protect their images from stealing?

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[quote name='savail' timestamp='1310211631' post='4833062']
Edit: I have got one more question: So how do great game developer firms protect their images from stealing?
[/quote]Lawyers.

For PC games, it usually makes sense to have one single data file for all the assets, since it can be more optimal to access, can be compressed, and so on. It's also possible to encrypt them if you really want, but as has been mentioned, if the assets are loaded into D3D or OpenGL, they can be pulled out easily. The point is that the single data file is usually created for reasons other than protecting them, but the obscurity is just a nice side effect.

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[quote]anyone with the simplest of tools can view them. Just run the game through PIX and you can view all of the textures, models, shaders and other assets it loads or creates.[/quote]

according to [url="http://msdn.microsoft.com/en-us/library/ee417250%28v=VS.85%29.aspx"]MSDN[/url]
[quote]
calling [url="http://msdn.microsoft.com/en-us/library/microsoft.directx_sdk.reference.d3dperf_setoptions%28v=VS.85%29.aspx"]D3DPERF_SetOptions[/url](1) tells PIX to not analyze the application.
[/quote]

didn't try it, but that would eliminate the ability to view or hack the media via PIX - does this "anyone" still have any other chances to view the media?

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