Design Overview

<Signature> 
  <SignedInfo>
    (CanonicalizationMethod)?
    (SignatureMethod)
    <Reference (URI=)? >
      (Transforms)?
      (DigestMethod)
      (DigestValue)
    </Reference>)+
  </SignedInfo>
  (SignatureValue) 
 (KeyInfo)?
 (Object)*
</Signature>