Implement custom authorization in C#

[Sample of Jul 7th] Implement custom authorization in C#:

Sample Download : http://code.msdn.microsoft.com/CSCustomAuthorization-241c2ff7 
The .NET Framework provides an extensible framework for authorizing and authenticating users.
This sample demonstrates how to implement custom authentication and authorization by using classes that derive from IIdentity and IPrincipal. It also demonstrates how to override the application thread's default identity, the Windows identity, by setting CurrentPrincipal to an instance of the class that derives from IPrincipal. Based on credentials supplied by the user, we can provide access to resources based on that role.
1. To create a class that implements IIdentity. An identity object represents the user on whose behalf the code is running.
2. To create a class that implements IPrincipal. A principal object represents the security context of the user on whose behalf the code is running, including that user's identity (IIdentity) and any roles to which they belong.
3. Collect user information to authenticate user. Then sets the thread's  current principal for role-based security)

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