W. Curtis Preston, the author of "The Storage Security Handbook" and "Unix Backup & Recovery," begins with an overview of the security problems that companies are trying to address with encryption and authentication systems. He then explains the three basic ways to encrypt sensitive data: encryption at the source, encryption with a backup application and hardware encryption. Preston offers insight into the advantages and disadvantages of each option, paying special attention to the cost of implementation and management of such systems. Additionally he reveals how enhanced authentication systems make encryption useful, for without proper authentication, encryption is useless.