I'm dealing with a security problem in a global assembly that I've created
and need some guidance.

The assembly is used by many different client programs, so the installer of
each one installs it in the Global Assembly Cache (which may end up with
multiple versions in a side-by-side fashion).

The assembly reads and writes to a file in the C:\Program Files\Common
Files\<CompanyName> sub-folder.

It also writes to a registry key in HKLM\Software\<CompanyName\... sub-key.

Both of these happen during both installation and run-time operation.

In terms of reducing my dependency on priviledged operations... I could
theoretically get rid of the latter (i.e. the reg key write), because it
only writes the name of the file that I created with the former (i.e. in the
<CommonFilesFolder>\<CompanyName\... subfolder). That is, I could fix the
filename to one specific filename and always assume that one filename, so I
wouldn't need to update the registry key. However, since the assembly is
used by different users, I don't know where else to put it besides somewhere
that is non-user-specific. I suppose that putting it in <AppDataFolder>
would be more appropriate than <CommonFilesFolder>, but I don't think that
will solve my problem. And once it is in a non-user-specific location, I
have trouble accessing that location to write a file on a limited account.

I've read (without much comprehension, unfortunately) about security
attributes that I can add to my assembly indicating what kinds of
permissions I need. However, I've seen things like:

[assembly:FileIOPermissionAttribute(SecurityAction.RequestMinimum,
All="C:\\example\\sample.txt")]

Is this for real? I can only use this if I hard-code the path to the file I
want access to? That can't be the way this really works, is it?

At the very least, can't we abstract some of the path (c.f.
Environment.SpecialFolder.CommonProgramFiles rather than "C:\\Program
Files\Common Files...").

The assembly *installs* okay because we encourage users to run the setup
with 'Run as Administrator' (in Vista, and as Administrator on XP), without
which, we couldn't install in the global assembly cache. I'm hoping that I
can specify some attributes or even run-time requests that basically say,
"If the user installs this as an administrator, then whenever this code is
used, it will automatically be allowed to write to that file system
location".

Is such a thing possible?

Thanks,
Bob