Represents the hash of the payload in its encrypted state.
Hash value is not meant to be taken over the Base64-encoded
state of the payload when used with a Base64Binary payload.
Used to represent the payload as stored and transmitted: Encrypted and split into
chunks as needed.
Used by tools that need to verify that a payload corresponds to the XML document,
but which have no reason to further process the payload and may not have access to
the necessary keys.