XML Digital Signatures •  Chapter 5 181 Q: What is the difference between RECOMMENDED and OPTIONAL in the standards? A: A RECOMMENDED feature is one that the standard suggest should be implemented. But the implementer can choose not to for any reason, and still claim compliance to the standard. An OPTIONAL feature is truly optional, the implementer is completely free to make a decision about including such a feature. Q: Are Digital Signatures legally binding, like a signature in ink? A: Generally, no, although in some places it is, for example Florida.This may change with time as the legal profession gains familiarity and comfort with using digital signatures. Q: What are the advantages of XML digital signatures over other digital signa- tures? A: XML digital signatures have the advantage of being an open standard. As such, they can be utilized in a wide variety of applications and on many plat- forms. XML digital signatures are also very flexible and can be applied to many different types of situations, such as signing portions of documents or using multiple signers. Q: How can an XML digital signature be created using alternative encryption schemes? A: Alternative encryption mechanisms can be defined in the <SignatureMethod /> element.The applications that will create and verify the signatures will need to be enhanced in order to understand the new method in the specifi- cation. Alternative encryption methods should be public key systems in order to retain the non-repudiation property of the signature. www.syngress.com Frequently Asked Questions The following Frequently Asked Questions, answered by the authors of this book, are  designed  to  both  measure  your  understanding  of  the  concepts  presented  in this chapter and to assist you with real-life implementation of these concepts. To have  your  questions  about  this  chapter  answered  by  the  author,  browse  to www.syngress.com/solutions and click on the “Ask the Author” form.