[det]xmld_verify_signature(+DOM,
+SignatureDOM, -Certificate, +Options)ds:Signature element contains a valid
signature. Certificate is bound to the certificate that
appears in the element if the signature is valid. It is up to the caller
to determine if the certificate is trusted or not.
Note: The DOM and SignatureDOM must have
been obtained using the load_structure/3
option keep_prefix(true) otherwise it is impossible to
generate an identical document for checking the signature. See also xml_write_canonical/3.