How can I write a secure class? How to apply security to a class?

You can change the DACL on the registry hive you want to allow access to.
There are lots of aspects to security but at a minimum are listed below:

* never trust input data: validate it and/or encode it before using it or echo'ing it back
* be very careful about constructing SQL queries in text using user input. Prefer paramterized stored procedures if you can use them.
* Validate arguments to p/invoke calls and minimize the use of "unsafe" code in C#

There is a white paper http://msdn.microsoft.com/library/defaultasp?url=/library/en-us/dnbda/html/authaspdotnet.asp with more recommendations and considerations.


With Best Regards,
Mitesh Mehta
Email : miteshvmehta@gmail.com
http://cc.1asphost.com/miteshvmehta/