Writing secure .NET code requires three things: an understanding of the .NET code security system, attention to detail, and the ability to think from the point of view of an attacker. This book provides a practical guide to the .NET security framework, and also demonstrates best practices to follow and worst practices to avoid. There is no such thing as foolproof security but the techniques demonstrated in this book will go a long way towards making your code secure in the face of attackers.
As well as knowing how to write secure code, it is also important to be able to spot holes in your own and others code. This book provides many examples of common vulnerabilities (and how to mitigate them) to help you learn this important skill.
Although this book primarily focuses on .NET code access security other aspects of security such as the Window role based security model, cryptography, and calling unmanaged code are covered where relevant.