
470 • XML & Related Technologies
A message digest or hash produces a fixed-length unique representation (called fingerprint) of
a message.
When a message digest is encrypted with the sender's private key, the output produced is called the
digital signature of the message.
In an XML digital signature, a message or a document is treated as consisting of many elements,
and it provides for the signing of one or more such elements. This makes the signature process
flexible and more practical.
XML digital signatures can be classified into three types: enveloped, enveloping and detached.
In the enveloped XML digital signatures, the ...