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C# - Locking folders from being edited

i'm making a small project. it's Windows Form Application. i got some sources in a folder (C:/sources). When my program runs, it uses sources from the folder. Currently i can edit the folder by windows explorer, it can cause errors for my program. So i want to lock the folder (C:/sources) from being edited/renamed/deleted when my program runs. How to do so?
EDIT;
Is it possible to show a message like this when user has tried to edit the folder:
"the action cannot be completed because the folder or a file in it is open in another program"
the program that we are talking about is mine..

There are a couple of approaches that you could venture and they vary in difficulty of implementation. It all depends on how important this task is for you. But, before discussing these options; can't you embed those resources in your WinForms application instead? If this is not an option then you can do one of the following:
Write a device driver that can prohibit the access of such resources if your application is running. There are fallbacks to this approach. For example one can impersonate your application by having the same name. But, am not getting in to too much details in trying to break any approach as I am trying to address possible solutions to the current problem. There are different types of drivers that you can consider. Probably the simplest form of this approach would be to implement a mini-filter driver.
Hook certain API's like CreateFile(), NtCreateFile(), ZwCreateFile() although there are many ways to circumvent such mechanism of defense. But, again we are only venturing what you can do to address this constraint of yours.
Open these resources directly from your application and lock it exclusively. For example:
File.Open("test.txt", FileMode.Open, FileAccess.Read, FileShare.None);
as this will result in people getting the message that you desire if they try to open the file.
Maybe you can give more information on what these resources are and we can help you determine which is the best way to protect your files in a reasonable fashion?

Although I don't believe it's the best idea to have files that are critical to the application in a open area like the C: drive, I would look into NTFS file permissions and set the folder to read only, but this wont stop administrative users
See these two posts
restrict access to folder outside of program c#
Setting NTFS permissions in C#.NET

How to track directory opening

I'm not sure if the question's title makes sense, and I'm sorry if it doesn't; I didn't really know what to title it.. Anyway, is there a way to make your program track the viewing of a folder?
What I'm trying to achieve: Windows 7 Home Premium doesn't allow encryption. So, I made a folder inside my user directory, and set it to hidden. Although, you can easily find it by changing windows settings.. So, is there a way to make a program pull up a window if the user tries to access that certain folder?

I don't think you can detect the "opening" of a folder.
Instead, you may want to set a FileSystemWatcher to detect any file access to the files in that particular folder.
Hope this helps.

First of all, I have to wonder why you're not just setting an ACL on the directory to prevent access.
However, it sounds like you want to find when somebody is accessing a particular directory. To do this, you enable filesystem auditing, then set the audit ACL to generate audit entries for "List folder". This will cause entries to be generated in the Security Event Log whenever the directory is viewed.
Now you just have to write a program that watches the Security event log looking for entries indicating that somebody has listed the directory in question and take action as necessary.

Well, there is an article on code project describing how you can hook into windows system calls: http://www.codeproject.com/KB/system/hooksys.aspx - it's not simple though (and also not C#) and has the potential to screw with your system but if it might be a fun project to work on.
A simpler option would be: Use a 3rd party desktop encryption tool - not much programming involved here but it might do the job better than anything else.

Responding to interactions with files in C#?

I want to write a program that will encrypt an entire folder and it's sub-folders, I have no problem doing this but I would like to make the entire encryption process rather transparent by letting a user double click it and have it open as if it weren't encrypted, say if it were a picture or a word document and it'd open in it's respective application.
How can a running program of mine become notified about the opening of a target file, stop the file from opening, do what it needs to do (decrypt), followed by running the resulting decrypted file.
How can I watch a file and do this in C#? Can I watch for other interactions like the user copying a watched file (since it won't be in a watched folder, it should be decrypted i.e. it's dragged to a USB device), or for deleting a watched file (say if I want to shred a file before deletion)?
P.S. The FileSystemWatcher doesn't quite meet my needs. EDIT: What I mean is that FileSystemWatcher will tell me when a file is being opened, deleted and all those events, but it won't let me step in real quick, decrypt the file, and hand it back to the process that normally opens that file.

You can rename files, add them your own extension, like thepicture.jpg.encrypted. Set your program as a default program for this extension and handle opening them

It's impossible in C#. the bare minimum would need you to use user-mode hooks on NtCreateFile, NtOpenFile, etc. You can't achieve that in C#. That wouldn't even work properly due to kernel-mode code which may try to access your files. The proper way of doing this would be to write a I/O minifilter (in C of course).
EDIT: If you're really desperate, try EasyHook - it allows you to hook functions from C#. I haven't tried it though, and it does seem risky hooking vital functions like NtCreateFile. Plus you need a fair bit of Native API knowledge.

Are you using Windows? If so, why not use the built-in BitLocker?
See this link:
BitLocker drive encryption
If you are thinking about a competitive application to BitLocker, add a comment, as I can point you in that direction as well.

Instead of trying to reinvent the wheel, use NTFS file encryption. You can encrypt single files or entire folders or drives. Plus it's completely transparent to the user and does exactly what you asks (e.g. automatically decrypt when copying to a UBS drive, etc). Just use System.IO.File.Encrypt(string) - there couldn't be anything easier.

You can't do this from usermode.
Unfortunately the only way to do this is to write a minifilter driver. Minifilter drivers allow you to intercept IO requests to files, you can then encrypt/decrypt the files you care about on the fly.
It sounds simple, but encryption minifilter drivers are very, very, difficult to get right. You will have to end up shadowing file objects which is a real challenge. Check with www.osr.com, they have a ton of information on doing exactly what you want to do.
If you choose to go this route I would recommend getting a copy of VMWare Workstation and download VirtualKD. It will let you debug at near fire-wire speeds into a VM. I would start with x64 Win7 and get remote shares working first.

how to store data in c# application in a portable form?

I'm writing an application using windows form and c# 3.0. I was wondering if there is a recommended way of persist data across time. However, i do not want to touch the machine it is running on, as a result, i would like to store the data in the binary executable (preferably, due to the need not clutter up the user's folder with random config files).
So if anyone have any ideas of how to do this, it would be much appreciated!
Jason

If you're looking to store configuration information - app.config or a settings file is probably the way to go.
If you are storing user data - you should really allow the user to control where it is saved - and prefer the \User\Username folder on the machine.
As for what format to store it in ... you can certainly use something like SQLLite - but there's nothing wrong with XML either, if you're not storing true binary data. .NET offers a number of APIs to transform object graphs into XML representations - which you may want to look into.
If you don't want to store anything on the local user's machine, you probably want a network database - or a webservice - to which you upload the users data. Just make sure your users understand this - many don't like their private data being sent somewhere on the web without their consent.
You really don't want to go about modifying the executable file. Many virus scanners quarantine executables that are constantly changing in content or size - as a way to proactively prevent viruses and malware from infecting the machine. You don't want to go there.

Do not modify the executable. Adding a single SQLite database is a much better solution.

Isolated storage is another alternative.
Doesn't clutter install directory
Doesn't cause issues with AnitVirus software
Part of the OS including .Net objects, don't need to install anything else
Already works with the Windows security model
Exists on a per user basis, so saved settings are separated for each user
Can serialize/deserialize obects directly into it

SQLite is what your looking for and is compatible with c#

If you dont want to store data in a SQLite db on the end users PC you could call out to a web service on another server which stores it's data in SQL Server or something else.

I don't believe a windows form project can modify itself like that (I've tried to find a way to do this myself some time ago). Some form of hosted application such as a silverlight application (where the application is essentially a zip file) may be the way to go. Silverlight applications would require the silverlight plugin though (and I'm still not sure if a silverlight application is allowed to modify itself).
I would think that one config file of some sort would be prefereable, and not leave much clutter.
One way to ensure that your applicaiton is entirely self contained would be to use a program like ThinStall after you have compiled the project. This virtualises the application and could give it it's own file system or registry internally to the .exe file.
One way for an executable to change itself would be to put another executable inside it, (embed as a resource then extract it to a file when needed). This executable could then modify the first, however I don't think ther'es any framework for it to do that, so it would require knowing excatly what to change and where.

Restrict a directory that can be used only through a .net Application

I have a windows Application that stores certain files in a directory. I would like to know if there is a way in .net that I can restrict users not to have access to that directly (by just going to that directory in windows, and grab files) so only my application can add/verify/delete a file in that directory.

Could you use the Isolated Storage in .Net? While, it isn't necessarily restricted away from your users it may be a lot harder to find.... (stores under the local settings\application data\isolated storage for the logged in user)
Via code you work with it by using / importing the System.Io.IsolatedStorage and then you can create directories, files, etc... normal.
You also don't have to keep track of the actual directory on the HD it's in as .Net manages this. Maybe a nice plus.

This is only possible if your application runs with different credentials than the user running the application.
By default all applications run with the credentials of the user who launched the process. This means the application has the same directory and file restrictions as the user. Without a different account, the application can only decrease it's ability to access the file system, not increase it.
Dealing with the file system is evil in general. Even if you could get the user to not play in that directory you still can't trust the results will be in the exact same state as you left them. It's possible for other users, physical disk corruption or any number of other things to corrupt your files.
The only way to sanely program the file system is to expect failure from the start and count yourself lucky when it actually works.

The application needs to run as a specific user - and that user will always have the same rights as your application. You can, potentially, make a service that runs as an administrator to prevent standard users from accessing a directory, but the administrator will still be able to change things in the directory.
I suggest you look for another approach for your problem. There are potentially alternatives - perhaps you should consider keeping some type of encrypted hash on the directory contents. That would at least allow you to verify that the contents have not been changed, although it won't prevent the change from occurring.

As others have mentioned, you need the application to act as a different user than the ones currently logged in. You should look into 'impersonation', here are some links that can get you started on getting your application to act as a different user when performing certain tasks:
http://csharptuning.blogspot.com/2007/06/impersonation-in-c.html
http://www.codeproject.com/KB/cs/cpimpersonation1.aspx

The easiest (although not secure in any way) method, would be to use a hidden folder, which the users know nothing about. so \servername\hiddenfiles$
A more secure alternative would be to change the credentials the program is using to access the folder. Is it necessary for them to access it as themselves?
An alternative would be to create a dummy account for each user, where they do not know the password. Make it relate to their windows login, so domain\myname becomes domain\mynamehidden. Then use this to connect to the directory.
This will ensure everything can be audited nicely too.

Look at FileSystemWatcher - it doesn't prevent from changes in directory, but allows to notify program about changes in dir.