root namespace is added into the <xades:SignedProperties> - xml-signature

Question

library: apache Santuario + xades4j.
using xpathto select elements and sign them.
If I try to sign a simple XML without a namespace and verify the signature, it works well , but if the XML defines a namespace, for example the XML following:
<ClinicalDocument xmlns="urn:hl7-org:v3">
<element1tobesigned.../>
<element2tobesigned.../>
</ClinicalDocument>
and the exception was found when verifying the signature
858 WARN [main] org.apache.xml.security.signature.Reference - Verification failed for URI "#xmldsig-5fb20abe-b14c-4d84-a908-e22e776cd6f1-signedprops"
858 WARN [main] org.apache.xml.security.signature.Reference - Expected Digest: q0WnWFf9j0kcT46t5cXmcPnVvu5o51oAcmej/SjCazQ=
858 WARN [main] org.apache.xml.security.signature.Reference - Actual Digest: 41zXKVkRCsxUYpNZXW5b9KkZlTC9LM9WA8O7WHQz1Rg=
xades4j.verification.ReferenceValueException: Reference '#xmldsig-5fb20abe-b14c-4d84-a908-e22e776cd6f1-signedprops' cannot be validated
the cause is that XML namespace (urn:hl7-org:v3) was added into the xades:SignedProperties then the digest became different .
858 DEBUG [main] org.apache.xml.security.utils.DigesterOutputStream - Pre-digested input
858 DEBUG [main] org.apache.xml.security.utils.DigesterOutputStream - <xades:SignedProperties xmlns="urn:hl7-org:v3" ........./>
here is the signature generation code
XadesTSigningProfile profile = new XadesTSigningProfile(keyProvider);
profile.withTimeStampTokenProvider(TestTimeStampTokenProvider.class)
.withAlgorithmsProviderEx(ExclusiveC14nForTimeStampsAlgorithmsProvider.class);
XadesSigner signer = profile.newSigner();
DataObjectDesc obj1 = new DataObjectReference("")
.withTransform(new ExclusiveCanonicalXMLWithoutComments())
.withTransform( new XPathTransform(xPath);
SignedDataObjects dataObjs = new SignedDataObjects().withSignedDataObject(obj1);
changed 2012-11-20 begin
// signer.sign(dataObjs, docToSign.getDocumentElement() );
new Enveloped(signer).sign(docToSign.getDocumentElement());
changed 2012-11-20 end
and here is the verify code
NodeList signatureNodeList = getSigElement(getDocument("my/my-document.signed.bes.countersign.xml"));
for (int i = 0; i < signatureNodeList.getLength(); i++) {
Element signatureNode = (Element) signatureNodeList.item(i);
verifySignature(signatureNode, new XadesVerificationProfile(VerifierTestBase.validationProviderMySigs));
log.info("successful validation");
}
public static XAdESForm verifySignature(Element sigElem,
XadesVerificationProfile p) throws Exception {
XAdESVerificationResult res = p.newVerifier().verify(sigElem, null);
return res.getSignatureForm();
}
It looks like that there is a document about this problem in Apache Santuario FAQ ,
2.6. I sign a document and when I try to verify using the same key, it fails
After you have created the XMLSignature object, before you sign the document, you must embed the signature element in the owning document (using a call to XMLSignature.getElement() to retrieve the newly created Element node from the signature) before calling the XMLSignature.sign() method,
During canonicalisation of the SignedInfo element, the library looks at the parent and ancestor nodes of the Signature element to find any namespaces that the SignedInfo node has inherited. Any that are found are embedded in the canonical form of the SignedInfo. (This is not true when Exclusive Canonicalisation is used, but it is still good practice to insert the element node prior to the sign() method being called).
If you have not embedded the signature node in the document, it will not have any parent or ancestor nodes, so it will not inherit their namespaces. If you then embed it in the document and call verify(), the namespaces will be found and the canonical form of SignedInfo will be different to that generated during sign().
also there is a document about this problem as following
https://stackoverflow.com/a/12759909/1809884
It looks like that it is not a bug of xades4j, but a xml signature problem.
--add 2012-11-15
here is how to get the docToSign . in fact , i just reused the code in class SignatureServicesTestBase . so i am sure that it is namespaceaware.
static
{
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setNamespaceAware(true);
db = dbf.newDocumentBuilder();
}
public static Document getDocument(String fileName) throws Exception
{
String path = toPlatformSpecificXMLDirFilePath(fileName);
Document doc = db.parse(new FileInputStream(path));
// Apache Santuario now uses Document.getElementById; use this convention for tests.
Element elem = doc.getDocumentElement();
DOMHelper.useIdAsXmlId(elem);
return doc;
}
and docToSign is return by calling SignatureServicesTestBase.getDocument()
Document docToSign = SignatureServicesTestBase.getDocument("my/cdamessage.xml");
and the SignedProperties element as following
<xades:SignedSignatureProperties>
<xades:SigningTime>2012-11-15T13:58:26.167+09:00</xades:SigningTime>
<xades:SigningCertificate>
<xades:Cert>
<xades:CertDigest>
<ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
<ds:DigestValue>4btVb5gQ5cdcNhGpvDSWQZabPQrR9jf1x8e3YF9Ajss=</ds:DigestValue>
</xades:CertDigest>
<xades:IssuerSerial>
<ds:X509IssuerName>CN=Itermediate,OU=CC,O=ISEL,C=PT</ds:X509IssuerName>
<ds:X509SerialNumber>-119284162484605703133798696662099777223</ds:X509SerialNumber>
</xades:IssuerSerial>
</xades:Cert>
<xades:Cert>
<xades:CertDigest>
<ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
<ds:DigestValue>vm5QpbblsWV7fCYXotPhNTeCt4nk8cLFuF36L5RJ4Ok=</ds:DigestValue>
</xades:CertDigest>
<xades:IssuerSerial>
<ds:X509IssuerName>CN=TestCA,OU=CC,O=ISEL,C=PT</ds:X509IssuerName>
<ds:X509SerialNumber>-46248926895392336918291885380930606289</ds:X509SerialNumber>
</xades:IssuerSerial>
</xades:Cert>
<xades:Cert>
<xades:CertDigest>
<ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
<ds:DigestValue>AUaN+IdhKQqxIVmEOrFwq+Dn22ebTkXJqD3BoOP/x8E=</ds:DigestValue>
</xades:CertDigest>
<xades:IssuerSerial>
<ds:X509IssuerName>CN=TestCA,OU=CC,O=ISEL,C=PT</ds:X509IssuerName>
<ds:X509SerialNumber>-99704378678639105802976522062798066869</ds:X509SerialNumber>
</xades:IssuerSerial>
</xades:Cert>
</xades:SigningCertificate>
</xades:SignedSignatureProperties>
</xades:SignedProperties>
also , i use xpath to get the elements to be signed, and namespace(xmlns="urn:hl7-org:v3" ) is add into the result as well .
543 DEBUG [main] org.apache.xml.security.utils.ElementProxy - setElement("ds:Transform", "null")
544 DEBUG [main] org.apache.xml.security.utils.ElementProxy - setElement("dsig-xpath:XPath", "null")
658 DEBUG [main] org.apache.xml.security.utils.DigesterOutputStream - Pre-digested input:
658 DEBUG [main] org.apache.xml.security.utils.DigesterOutputStream - <component xmlns="urn:hl7-org:v3" Id="ES" contextConductionInd="true" typeCode="COMP">
<section classCode="DOCSECT" moodCode="EVN">
<code code="ES" codeSystem="2.16.840.1.113883.6.1" codeSystemName="SectionCode" codeSystemVersion="1.0" displayName="english"></code>
<text>english</text>
</section>
</component>
something wrong with xpath ? xpath is driving my crazy . I think i have to study xpath from beginning now.
chris

Answer 1

You're creating an enveloped signature but the enveloped signature transform is missing! Since the whole document is being signed the signature node itself has to be excluded, because some of its contents change after signature calculation.
Can't believe how I didn't see it until you mentioned the Enveloped class. Btw, this class is just an utility class for simple, straightforward enveloped sigantures. It robably shouldn't even be there. You can just add the transform yourself:
DataObjectDesc obj1 = new DataObjectReference("")
.withTransform(new EnvelopedSignatureTransform())
.withTransform(new ExclusiveCanonicalXMLWithoutComments())
...