Types of XML Digital Signatures
There are several ways to couple the signed resource with the signature generated for the resource (see Figure 4).
Figure 4 Types of XML digital signatures.
The generated signature is embedded within the signed XML element itself. Thus, the digital signature becomes a part of the XML document that is sent to the end consumer.
This category is applicable only if the signed resource is an XML.
The generated XML digital signature encloses the signed XML elements, which it authenticates. Even in this case, the digital signature is a part of the transmitted XML document.
Like its predecessor, this category is relevant only to XML formatted signed resources.
The signed XML document and the signature stand apart. This is most suitable for signing resources other than XML (for example, binaries and html files).
In such cases, the XML Signature <Reference> element usually carries the URI of the signed resource, which it authenticates.