Java XML DSig和XPath

我正在使用Java XML DSig API签名XML文档的一部分。我试图了解它是如何达到Digest值的。

我的文件是：

<?xml version=\"1.0\" encoding=\"UTF-8\"?><PurchaseOrder><foo>bar</foo></PurchaseOrder>

我的xpath表达式是：

PurchaseOrder/foo/text()

我试图做的是：

1. 调用Java DSIG库并查看生成的摘要的值。
2. 使用messageDigest（SHA-1）类可消化值“ bar”。
3. 验证1和2中的摘要是否匹配。

当我这样做时，1和2会产生不同的摘要值。我对DSIG代码的处理完全不对，或者我不了解DSIG的工作方式。有任何想法吗？

这是我的测试代码（抱歉，它太长了……我应该回到perl）：

public class GenerateXmlSignature2 {
    private static final String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><PurchaseOrder><foo>bar</foo></PurchaseOrder>";
    private static final String xpath  = "PurchaseOrder/foo/text()";

    public static void main(String[] args) throws Exception {
        Base64 base64 = new Base64();
        // Create a DOM XMLSignatureFactory that will be used to
        // generate the enveloped signature.
        final XMLSignatureFactory fac = XMLSignatureFactory.geTinstance("DOM");

        // Create a Reference to the enveloped document (in this case,// you are signing the whole document,so a URI of "" signifies
        // that,and also specify the SHA1 digest algorithm and
        // the ENVELOPED Transform.
        final List<XPathType> xpaths = new ArrayList<XPathType>() {
            {
                add(new XPathType(xpath,XPathType.Filter.UNION));
            }
        };
        List<Transform> transforms = new ArrayList<Transform>() {{
             add(fac.newTransform(
                Transform.XPATH2,new XPathFilter2ParameterSpec(xpaths)
            )
            );
        }};
        Reference ref = fac.newReference
                ("",fac.newDigestMethod(DigestMethod.SHA1,null),transforms,null,null);


        // Create the SignedInfo.
        SignedInfo si = fac.newSignedInfo
                (fac.newCanonicalizationMethod
                        (CanonicalizationMethod.INCLUSIVE,(C14NMethodParameterSpeC) null),fac.newSignatureMethod(SignatureMethod.RSA_SHA1,Collections.singletonList(ref));


        // Load the KeyStore and get the signing key and certificate.
        KeyStore ks = KeyStore.geTinstance("JKS");
        ks.load(new FileInputStream("mykeystore.jks"),"changeit".toCharArray());
        KeyStore.PrivateKeyEntry keyEntry =
                (KeyStore.PrivateKeyEntry) ks.getEntry
                        ("mykey",new KeyStore.passwordProtection("changeit".toCharArray()));
        X509Certificate cert = (X509CertificatE) keyEntry.getCertificate();

        // Create the KeyInfo containing the X509Data.
        KeyInfoFactory kif = fac.getKeyInfoFactory();
        List x509Content = new ArrayList();
        x509Content.add(cert.getSubjectX500Principal().getName());
        x509Content.add(cert);
        X509Data xd = kif.newX509Data(x509Content);
        KeyInfo ki = kif.newKeyInfo(Collections.singletonList(xd));

        // Instantiate the document to be signed.
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        dbf.setNamespaceAware(true);
        Document doc = dbf.newDocumentBuilder().parse
                (new ByteArrayInputStream(xml.getBytes()));

        // Create a DOMSignContext and specify the RSA PrivateKey and
        // LOCATIOn of the resulTing XMLSignature's parent element.
        DOMSignContext dsc = new DOMSignContext
                (keyEntry.getPrivateKey(),doc.getDocumentElement());

        // Create the XMLSignature,but don't sign it yet.
        XMLSignature signature = fac.newXMLSignature(si,ki);



        // Marshal,generate,and sign the enveloped signature.
        signature.sign(dsc);

        // Output the resulTing document.
        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer trans = tf.newTransformer();
        trans.transform(new DOMsource(doC),new StreamResult(System.out));



        System.out.println("\n\n*** SHA-1 Digest ***");
        XPathExpression xpathExpression = XPathFactory.newInstance().newXPath().compile(xpath);
        String data = xpathExpression.evaluate(new Inputsource(new StringReader(xml)));
        System.out.println("Xpath: " + data);
        messageDigest md;
        md = messageDigest.geTinstance("SHA");
        byte[] sha1hash;
        md.update(data.getBytes(),data.length());
        sha1hash = md.digest();
        String base64Sha1OfCanonicalXml = new String(base64.encode(sha1hash));
        System.out.println("Digest:   " + base64Sha1OfCanonicalXml);
    }
}