Urgently Needed

[wezaya]

I want to know if it is available in pocket pc programming using C# to do the following :

(if a user wanna open a file he clicks it, i want my program to not-open the file but first looks up the parameters of the open function (name of file) in a database then the decision whether to open the file or not is based on a specific criteria)


if this is aplicable, plz i want somebody to tell me how ,, if not plzzzzz, send me an alternative to it.... thanx in advance

Note: this is a piece in my graduation project , which really makes me mad and i need ur help really soooooooooooon

[Shaggy Hiker]

Well, if you want to coopt the file explorer, I can't help you. However, if you are simply using the Open dialog box (or whatever it is in the CF, I'm too lazy to look it up since it doesn't seem all that important), then all the dialog returns is the file name. The file isn't actually opened from the dialog. Therefore, you can do whatever you want with the filename.

So in short, the answer is: If you mean to filter the users ability to open any file from anything, I don't know how, but if you want to filter what the user opens from a program you wrote, then the answer is yes.

[wezaya]

Before any thing thanx alot for replying that soon.

Well, I was willing to make an appliacation to do the following:
1-only Palm's owner is the legal user of my application.
2-He decides (using my application) to make some files that is resident on his palm whether to be (openable or not,sendable via bluetooth or not,renamable or not,.......). In short, I wanted to develop an access controller.
3-My application has a little server which is always on, when any one takes this PPC and tried to send a file for another PPC, my program will simply, read the send's arguments, first it will see the file's name and looks it up in my application's database, if the file is there and having a limited access, it will stop the send process, if there is no access bans, send process is to be executed. That of course applies to any other action can be made to a file.

I know that I'm talking as if I'm trying to program a normal windows application for my Personal Computer rather than my PPC, As I'm a new immigrator from programming PCs to PPCs

any way, I liked the idea of having another browser, in it i will overwrite all options files have ( opening a file for example won't happen unless checked first if allowable or not), although I still think that it's really hard to do all this work , but I think the real trouble I have here is to disable the windows' browser , and instead to open and use my browser, even when you reach a file it from any other application ( I mean like to open Microsoft word and browse for a specific file and then when reached, a right click will give you access to deleting the file for example) and like that any one can overcome my security program and my application is nothing!!

So, Can I make the only way to communicate with a file is through a special browser I develop ??

[Shaggy Hiker]

It seems to me that the easiest way to do this is not to prevent the file from being sent, but to prevent the file from being useable: encrypt it. To do anything else would require that your program be running at all times. This is mighty tough to ensure. For instance, I always try to put data files onto an SD card because the medium is so much more durable. You wouldn't be able to do this, because a user could circumvent your program with that little switch that all PDA's have: The memory switch. One click of that, and your program is gone (the same as Format C: on your desktop)....but data on the SD card is NOT gone.

To avoid this, you'd have to keep the data in the PDA memory, so that all the data is erased on a hard reset. Is that acceptible? Safe, perhaps, but sure is annoying, especially since letting the battery run down has the same effect. Seems like that would be quite secure, but really frustrating in short order.

I'd go on, but you might as well chew over that for a little while, I'd say that it strongly favors the encryption.

[wezaya]

Encryption...
U R So Right!!

I thought of encryption, but there is a little trouble with it.

It will make a file ( can't be opened )

but any other action will be done, like Deletion of a file, so again... How to really protect a file ?!!

[Shaggy Hiker]

You can't!

Oh, there is a way to have your app take over the PDA, though I don't know how it is done. This would be used in a situation like where a PDA is ONLY going to be used as a bar scanner, or something like that. No other programs can get the screen. However, I don't think even this is secure by the standards you are setting.

Just contemplate that hard reboot scenario I mentioned. That will ERASE any program you install. If there is ANY way to get around that, I don't know it.

[Strider]

Hey there, if you want your application to be that only thing thats accessbile on the device then you will want your application to be in "Kiosk Mode".
This restricts users access to other areas of the device.

There is a special engine you can buy to perform such functionality in your application (http://www.pocketpcdn.com/articles/kiosk.html)


Alternatively you can do the following.
1. Make all forms in your application Maximised. This prevents user from moving them around.
2. Disable the Start Menu and Taskbar. (Also set the start menu to autohide) This can be done throught code (search the forum im sure i've posted it before
3. In your application prevent the user from quiting the application (ask for a password to quit)

All the above works for Windows CE OS which most application i develop are targetted. I have not tried it on Pocket PC OS

Also it depends on what type of device you are using.

I generally use the Psion Teklogix Workabout Pro.

• They are available with the Pocket PC OS or Windows CE OS
• They also come with built in flash memory so if you install your application on the flash disk it will remain there even after cold reboot.
• Another feature they have is Total Recall where you can create an image of the OS with your applicaiton installed and shortcuts setup. The image can be set to autorestore which will happen if the device is reset, batteries die etc....
• Also if you create a startup folder on the flash disk of the device you can put a shortcut to you application and it will autolaunch when the device is booted.

[Shaggy Hiker]

Well, that device is the only one I know of that has the features you would need to avoid the total reset problem. My Toshiba sure doesn't have any of that, though it would be REALLY nice, especially the autorestore feature.

[wezaya]

It's me again

I found a good solution

I will Encrypt the file, save it's path, delete original file, and move the encrypted file into a new folder which is hidden. When I want to play the file, I will decrypt it giving it's old path..
Now, no body can ofcourse open, rename or delete it

But as usual

I have troubles with Compact Framework

I need a light Encryption method (How nice if in C# )

And also need to know how to set a folder property to be hidden

And realllllly thanx for helping me