Congratulations! You have made it through the introductory parts of this book. Now our look at the real XML Security parts begins.
Part III deals with authentication that is, digital signatures, message authentication codes, and the like. For a language as malleable as XML, a critical part of any nontrivial authentication is canonicalization. Chapter 9 goes into that topic in great depth.
Armed with an understanding of canonicalization, we then dive into the XML Digital Signature standard (XMLDSIG) in Chapter 10.
Chapter 11 gives several examples of profiling XMLDSIG for particular applications. You should view XMLDSIG as a toolbox. Almost any particular use will require restrictions on the wide range of things you can do with XMLDSIG; some will also require extensions to XMLDSIG.
Finally, Chapter 12 gives a snapshot of the effort under way to specify XML-based digital signatures that will conform to European government directives and qualify thereunder as trusted.