How to decrypt to get the message digest?

Question

Ok, I'm aware that, message digest, is a one-way hash algorithm. From what I gathered, we can decrypt then use the MessageDigest method, IsEqual to compared the hash value to ensure they are the same right?
But my problem is, right now, I has the code to encrypt and digitally signed on a xml.
But no one has used it before to decrypt. So i need to find out how.
Below is the code to generate the signed XML.
Can anyone tell me how to decrypt it?
Thanks...
    public boolean generateSignXmlDocument(String xmlDocPath, String newDocPath, KeyStore keystore, String alias, String password)
        boolean status = false;
        try
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            dbf.setNamespaceAware(true);
            DocumentBuilder builder = dbf.newDocumentBuilder();
            File f = new File(xmlDocPath);
            Document doc = builder.parse(new FileInputStream(f));
            KeyPair kp = getPrivateKey(keystore, alias, password);
            DOMSignContext dsc = new DOMSignContext(kp.getPrivate(), doc.getDocumentElement());
            String providerName = System.getProperty("jsr105Provider", "org.jcp.xml.dsig.internal.dom.XMLDSigRI");
            log.info("Creating xml sign.....");
            log.debug("Provider Name " + providerName);
            XMLSignatureFactory fac = XMLSignatureFactory.getInstance("DOM", (Provider)Class.forName(providerName).newInstance());
            javax.xml.crypto.dsig.Reference ref = fac.newReference("", fac.newDigestMethod("http://www.w3.org/2000/09/xmldsig#sha1", null), Collections.singletonList(fac.newTransform("http://www.w3.org/2000/09/xmldsig#enveloped-signature", null)), null, null);
            javax.xml.crypto.dsig.SignedInfo si = fac.newSignedInfo(fac.newCanonicalizationMethod("http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments", null), fac.newSignatureMethod("http://www.w3.org/2000/09/xmldsig#rsa-sha1", null), Collections.singletonList(ref));
            KeyInfoFactory kif = fac.getKeyInfoFactory();
            javax.xml.crypto.dsig.keyinfo.KeyValue kv = kif.newKeyValue(kp.getPublic());
            javax.xml.crypto.dsig.keyinfo.KeyInfo ki = kif.newKeyInfo(Collections.singletonList(kv));
            XMLSignature signature = fac.newXMLSignature(si, ki);
            signature.sign(dsc);
            java.io.OutputStream os = new FileOutputStream(newDocPath);
            TransformerFactory tf = TransformerFactory.newInstance();
            Transformer trans = tf.newTransformer();
            trans.transform(new DOMSource(doc), new StreamResult(os));
            status = true;
        catch(Exception e)
            log.error(e);
        return status;
    }

Answer 1

Kyle Treece wrote:
It says that both IMAP and POP are enabled in my settings.
what settings ? in gmail webmail interface? I'm talking about how your gmail account is configured in Mail on your computer. It's configured for POP. you need to delete it from Mail and then create a new account in Mail and make it IMAP. do not use automated account setup which Mail will offer to do. that will make the account POP again. enter all server info and account type by hand.
see this link for details
http://mail.google.com/support/bin/answer.py?answer=81379
If I turn POP completely off, will it kick all the messages out of my iPhone?
as I said, this is not about turning something on or off in webmail gmail. you have to configure your email client Mail correctly. it will have no effect on your iphone.