Re: Compute XML Signature on external Xml document

From: Ivan Medvedev [MS] (ivanmed_at_online.microsoft.com)
Date: 05/21/03 

Date: Wed, 21 May 2003 09:56:37 -0700

J-P -
you will need to use an EnvelopedSignatureTransform. Here is approximately
how you would do this:

------------------------- sign --------------------------
  XmlDocument doc = ... // your enveloping document
  SignedXml signedXml = new SignedXml(doc);
  signedXml.SigningKey = ... // your signing key
  Reference reference = new Reference();
  reference.Uri = "";
  XmlDsigEnvelopedSignatureTransform env = new
XmlDsigEnvelopedSignatureTransform();
  reference.AddTransform(env);
  signedXml.AddReference(reference);
  ... // add key info if neccessary
  signedXml.ComputeSignature();
  // now insert the signature into the doc
  XmlElement xmlDigitalSignature = signedXml.GetXml();
  XmlTextWriter xmltw = new XmlTextWriter( _name_ , new
UTF8Encoding(false));
  doc.DocumentElement.AppendChild(doc.ImportNode(xmlDigitalSignature,
true)); // insert the signature into the document
  if (doc.FirstChild is XmlDeclaration) doc.RemoveChild(doc.FirstChild);
  doc.WriteTo(xmltw);
  xmltw.Close();

------------------------ verify ---------------------------
        XmlDocument xmlDocument = new XmlDocument();
        xmlDocument.PreserveWhitespace = true;
        xmlDocument.Load(_name_);
        SignedXml signedXml = new SignedXml(xmlDocument);
        XmlNodeList nodeList =
xmlDocument.GetElementsByTagName("Signature");
        signedXml.LoadXml((XmlElement)nodeList[0]);
        return signedXml.CheckSignature();

-----------------------------------------------------------

Hope this helps.
--Ivan
This posting is provided "AS IS" with no warranties, and confers no rights.

"J-P Meunier" <fuimens@yahoo.fr> wrote in message
news:eGEI053HDHA.2176@TK2MSFTNGP10.phx.gbl...
> Hi all,
>
> I need to make an Xml Signature
(System.Security.Cryptography.Xml.SignedXml)
> of an XmlDocument and then to include the signature into that XmlDocument.
>
> Example:
> <XmlSign>
> <Identity id="ToBeSigned">
> <Name>myName</Name>
> <Surname>mySignature</Surname>
> </Identity>
> <IdentitySignature>
> *SignedXml*
> </IdentitySignature>
> <XmlSign>
>
> The solution would be to create a SignedXml object and insert it
> <IdentitySignature>, to set the correct references and then to compute
the
> signature. But I can't to that because the XML element of SignedXml can't
be
> accessed before computing the signature ...
>
> So how can I solve that problem?
> Any comment would be appreciated,
>
> Thanks
>
> J-P
>
>

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