For a treatment of computer security and public-key encryption, this book has surprisingly little mathematical content. Instead, it focuses on the business case for PKI, and explains how various applications use trusted certificates. Key (pun intended) details get ample attention, including trusted and accurate time-stamping mechanisms, alternate certificate authorities, and PKI auditing. The procedure for acquiring certificates and establishing a PKI is also covered. It's the five case studies, though, that will most impress readers who prefer example to tutorial. The case studies show how organizations (including Perot Systems and the U.S. Patent and Trademark Office) implemented their PKIs. --David Wall