[Gllug] Java XML-signing

[t.clarke]

I am trying to figure out how I can generate an 'IRMarked' XML file for
 submission to the dreaded Government Gateway (in connection with
Payroll data).  At present the XML files do not have to be
'IRmarked', but apparently they will in the future,  which is
somewhat opf a pain......

The following Java code (truncated) was downloaded from the
HMRC website,  and have installed jamvm and java-common
on the Debian box.

However,  I am at a loss as to how make the thing work !

Some guidance would be much appreciated.



Tim
-----------

import java.io.*;
import javax.xml.parsers.*;
import java.security.*;

import org.w3c.dom.*;

import org.apache.xml.security.signature.*;
import org.apache.xml.security.transforms.*;
import org.apache.xml.security.Init;

import org.bouncycastle.util.encoders.Base64;

/**
 * This code generates an IRmark value for an input document.
 * The value is a base64 encoded SHA1 digest of a signature
 * transform over a certain style of document. The value has
 * to be placed inside documents to be signed by the XPE when
 * used in a EDS/IR deployment.
 *
 * The code has a number of jar dependencies:-
 *      xmlsec.jar - The Apache XML Security Library
 *      log4j-1.2.5.jar - The Apache Log utility
 *  xalan.jar - Apache XSLT/XPath processor
 *  xercesImpl.jar - Apache XML processor
 *  bc-jce-jdk13-114.jar - Bouncy Castle JCE library
 *
 *  The Bouncy Castle JCE provider is automatically downloaded
 *  by the Apache XML sec library build so you may already have
 *  that.
 */
public class IRMark {

   /**
    * Generate and print the IRmark.
    *
    * @param args - Pass the filename of the input document
    * @throws Exception
    */
        public static void main(String args[]) throws Exception {

                // Init the Apache XML security library
                Init.init();

                // Check we are given a file to work with
                if (args.length!=1) {
                        System.out.println("Use: IRmark <file> ");
                        return;
                }

                // Open the input file
                FileInputStream fis=null;
                try {
                        fis=new FileInputStream(args[0]);
                } catch (FileNotFoundException e) {
                        System.out.println("The file " + args[0] + " could not be opened.");
                        return;
                }

                // Load file into a byte array
                byte[] data=null;
                try {
                        int bytes=fis.available();
                        data=new byte[bytes];
                        fis.read(data);
                } catch (IOException e) {
                        System.out.println("Error reading file.");
                        e.printStackTrace();
                }

                // First part is to run the a transform over the input to extract the
                // fragment to be digested. This is done by setting up a Transforms
                // object from a Template and then executing against the input document

                // The transforms to be performed are specified by using the template XML below.
        String transformStr =
        "<?xml version='1.0'?>\n"
        + "<dsig:Transforms xmlns:dsig='http://www.w3.org/2000/09/xmldsig#' xmlns:gt='http://www.govtalk.gov.uk/CM/envelope' xmlns:i
        + "<dsig:Transform Algorithm='http://www.w3.org/TR/1999/REC-xpath-19991116'>\n"
        + "<dsig:XPath>\n"
        + "count(ancestor-or-self::node()|/gt:GovTalkMessage/gt:Body)=count(ancestor-or-self::node())\n"
                + " and count(self::ir:IRmark)=0 \n"
                + " and count(../self::ir:IRmark)=0 \n"
                + "</dsig:XPath>\n"
        + "</dsig:Transform>\n"
        + "<dsig:Transform Algorithm='http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments'/>\n"
        + "</dsig:Transforms>\n"
        ;

                // Parse the transform details to create a document
                DocumentBuilderFactory dbf=DocumentBuilderFactory.newInstance();
                dbf.setNamespaceAware(true);
                DocumentBuilder db=dbf.newDocumentBuilder();
                Document doc=db.parse(new ByteArrayInputStream(transformStr.getBytes()));

                // Construct a Apache security Transforms object from that document
                Transforms transforms = new Transforms(doc.getDocumentElement(), null);

                // Now perform the transform on the input to get the results.
        XMLSignatureInput input = new XMLSignatureInput(data);
        XMLSignatureInput result = transforms.performTransforms(input);

        // Uncomment this line to see transform output
        // System.out.println(new String(result.getBytes()));

        // Second part is to run output via SHA1 digest
        // This is done via the standard java.security API
                MessageDigest md = MessageDigest.getInstance("SHA");
                md.update(result.getBytes());
                byte[] digest=md.digest();

                // And finally print a Base64 of the digest with
                // The help of the BouncyCastle JCE library
                System.out.println("IRmark: " + new String(Base64.encode(digest)));
   }
}

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