Signing XML and Canonicalization

[Bill Tschumy]

I am trying to digitally sign some xml and am having a hard time understanding the canonicalization options. The code I'm using is derived from the examples at the bottom of:

http://java.sun.com/javase/6/docs/technotes/guides/security/xmldsig/overview.html

I am creating an "enveloped" signature. Here is the relevant code from the GenEnveloped example:

        // Create a DOM XMLSignatureFactory that will be used to generate the
        // enveloped signature
        XMLSignatureFactory fac = XMLSignatureFactory.getInstance("DOM");
 
        // Create a Reference to the enveloped document (in this case we are
        // signing the whole document, so a URI of "" signifies that) and
        // also specify the SHA1 digest algorithm and the ENVELOPED Transform.
        Reference ref = fac.newReference("", fac.newDigestMethod(DigestMethod.SHA1, null),
                                         Collections.singletonList(fac.newTransform(Transform.ENVELOPED,
                                                                                    (TransformParameterSpec)
                                                                                    null)),
                                         null, null);
 
        // Create the SignedInfo
        SignedInfo si = fac.newSignedInfo(fac.newCanonicalizationMethod(CanonicalizationMethod.INCLUSIVE,
                                                                        (C14NMethodParameterSpec)
                                                                        null),
                                          fac.newSignatureMethod(SignatureMethod.DSA_SHA1, null),
                                          Collections.singletonList(ref));
 

I would like the canonicalization method to ignore whitespace outside of xml elements. Thus, the addition of a blank line wouldn't change the signature. None of the standard options to newCanonicalizationMethod() [INCLUSIVE, INCLUSIVE_WITH_COMMENTS, EXCLUSIVE, EXCLUSIVE_WITH_COMMENTS] do this. Is it possible? This seems like a reasonable thing to do so I'm surprised it is not more obvious.