XML signature

[Andrius <an...@kada.lt>]

  Hi,

  I'm using a client side handler to sign a SOAP message before it is
  sent to the axis web. Which seems to work fine, I can verify the
  signature validity after signing it. But when the web service
  receives this message it fails to validate the signature and throws
  a NullPointerException. My server side handler code looks like this:

public class VerificationHandler extends BasicHandler
{
    static
    {
        org.apache.xml.security.Init.init();
    }
    
    public void invoke(MessageContext ctx) throws AxisFault
    {
        try
        {
            String BaseURI = "http://xml-security";
            Message req_msg = ctx.getRequestMessage();
            Document doc=req_msg.getSOAPEnvelope().getAsDocument();

            Element nsctx = doc.createElement("nsctx");
            nsctx.setAttribute("xmlns:ds", Constants.SignatureSpecNS);
            Element signatureElem=(Element)XPathAPI.selectSingleNode(doc,"//ds:Signature",nsctx);

            if(signatureElem==null)
            {
                System.out.println("The document is not signed");
                throw new RemoteException("Document is not signed!");
            }

            XMLSignature sig=new XMLSignature(signatureElem, BaseURI);
            
            SignedInfo sinfo = sig.getSignedInfo();
            PublicKey pubkey = sig.getKeyInfo().getPublicKey();

            System.out.println("checking...");
            boolean valid=sig.checkSignatureValue(pubkey);  // <---FAILS HERE---
            System.out.println("done");
            
            if(!valid)
            {
                System.out.println("The document signature was forged!");
                throw new RemoteException("The document signature was forged!");
            }
            else System.out.println("The document signature is VALID!");
        }
        catch(Exception e)
        {
            throw AxisFault.makeFault(e);
        }
    }
}

The strange thing is that sometimes it works and sometimes it throws
an exception, I spent a whole day debuging but couldn't figure out
what makes it behave like that. Anyone has any ideas? Thanks in advance.

    Andrius