The first edition of this book was extremely good and this version is even better. As a source on crytographic programming this can't be bettered (note that it is much better than the O'Reilly book 'Java Crytography' which is hopelessly out of date). However, it also provides thorough coverage of code security - the famous sandbox, the class loader and the security manager. Finally, the book covers JAAS, the Java Authentication and Authorization Service. Here, unfortunately, the book gets a little sketchy and the examples are poor. Overall, however, this is a fine book and well up to O'Reilly standards.