This is a clear, consise, and easy to read book on IDM and DRM. I recommend it HIGHLY to anyone who wants an overview of IDM and its roots in the X.500 space. While Digital Identity does not specifically address certain concepts such as roles management, it is an essential resource for anyone’s library of identity management books. I understand that this book is now out of print; this is unfortunate as I was looking forward to a 2nd edition.