Our primary goal in writing this book is to explain the .NET Framework security system in detail and make it easy to understand. As a group, the authors have over 10 years of combined experience as members of the .NET Framework security product team at Microsoft. We have gathered together in this book our combined advice, experience, and wisdom to help you make the .NET Framework security system best serve your needs. We hope that you will find this book useful not only as an introduction to the fundamental security features of the .NET Framework but also as a frequent desktop reference as you author or administer applications.

This book is designed to serve the security needs of .NET developers, administrators, and end users. Developers who are currently writing code in one or more .NET languages (or planning to start a coding project) will find detailed instructions on how to perform security checks, how to write code conforming to the "principle of least privilege," and how to include security in your software architectures from the outset. For example, we will teach you how to use cryptographic strong names to protect your programs from outside modification and guarantee that they run with the same shared libraries with which you intended for them to run. We will also demonstrate how to create "semipublic" application programming interfaces (APIs) that can only be called by identities you specify. Debugging security exceptions and interpreting the data returned by the Common Language Runtime when your code is denied access to some protected operation are also covered in this book. Everything you need to know to develop secure components and applications is contained herein.

If you are an administrator, you will find in the following chapters detailed examples showing how to modify security policy to tighten or loosen it as needed for your particular environment. We will walk you through all the common policy modification scenarios and show you how you can configure an entire enterprise from one location through the use of the .NET Framework's security configuration tool and the Windows Active Directory. We will also explain ASP.NET configuration for deploying secure Web Services with authentication and authorization customized to fit your needs.

For end users, our primary task in this book is to demonstrate how you can control the security behavior of .NET Framework applications running on your machine. Depending on your particular situation, you may need to administer portions of your security configuration to allow or refuse rights to particular applications. You may have encountered a security exception while executing an application and want to know why that exception occurred. You might also be trying to use a Web Service and need to understand its security requirements. All of these topics are covered in this book.