XML Digital Signatures •  Chapter 5 161 </KeyValue> </KeyInfo> </Signature> </Envelope> All Together Now: An Example of Multiple References We can combine these basic forms in whatever way is necessary for a particular use. In particular, we can sign multiple messages by having an appropriate Reference  element for each data message.We can even create a digital signature that is enveloped and enveloping a detached all at the same time. Figure 5.10 shows how easily this can be done. (For the sake of brevity, we do not show the canonical template—by now you can see what it should look like. Figure 5.10 An Enveloped XML Signature, Enveloping and Detached Simultaneously <?xml version="1.0" encoding="UTF-8"?> <Envelope xmlns="urn:envelope"> <Signature xmlns="http://www.w3.org/2000/09/xmldsig#"> <SignedInfo> <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC- xml-c14n-20010315"/> <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa- sha1"/> <Reference URI="file:///home/skip/xml/weather.xml"> <Transforms> </Transforms> <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/> <DigestValue>NQb4am0ZWOLeZmw1MTZ60hNOAWA=</DigestValue> </Reference> <Reference URI=""> <Transforms> <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped -signature"/> www.syngress.com Figure 5.9 Continued Continued