Securing .NET Assemblies

25 Aug 2005 8:19 PM

sendhil.an@gmail.com

Hi,
I have a .NET assembly (a dll which has a strong name). It has two
classes. This dll is used in more than one application.

When the applications are distributed, the dll is also available for
anybody. I want to secure the assembly(dll), so that the class in the
assembly is inaccesible to the users.

I tried using LinkDemand in the dll.
[StrongNameIdentityPermission(SecurityAction.LinkDemand,
PublicKey = "")]

The problem with that is, iam not able to use the dll myself. I get
the following errror when instatiating a class in the dll. How do i get
access to the class but not others?

Error:
An unhandled exception of type 'System.Security.SecurityException'
occurred in Unknown Module.

Additional information: Request for the permission of type
System.Security.Permissions.StrongNameIdentityPermission, mscorlib,
Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
failed.

Thanks
sendhil

25 Aug 2005 9:49 PM

Dominick Baier [DevelopMentor]

Hello sendhil,

is the PublicKey really empty in your code??

besides that - LinkDemands will only guard against partially trusted clients.
A full trusted client can alway assert the required permission. In .NET 2.0
they are not even checked for fully trusted callers.

---------------------------------------
Dominick Baier - DevelopMentor
http://www.leastprivilege.com

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> Hi,
> I have a .NET assembly (a dll which has a strong name). It has two
> classes. This dll is used in more than one application.
> When the applications are distributed, the dll is also available for
> anybody. I want to secure the assembly(dll), so that the class in the
> assembly is inaccesible to the users.
>
> I tried using LinkDemand in the dll.
> [StrongNameIdentityPermission(SecurityAction.LinkDemand,
> PublicKey = "")]
> The problem with that is, iam not able to use the dll myself. I get
> the following errror when instatiating a class in the dll. How do i
> get access to the class but not others?
>
> Error:
> An unhandled exception of type 'System.Security.SecurityException'
> occurred in Unknown Module.
> Additional information: Request for the permission of type
> System.Security.Permissions.StrongNameIdentityPermission, mscorlib,
> Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
> failed.
>
> Thanks
> sendhil