Re: Xmldsig Countersignature DigestValue

On Mar 27, 12:31 pm, "Iguana" <szewcz...@xxxxxxxxxxxxxxx> wrote:
Hi!
I have create signatures with csharp (vc 2005) and net 2.0.
I think preserwe white spaces is not a problem in my code - this works
fine (with my code I verify signature have generated in java -
verification works good).
What I do exacly in my code:
read from xml document all tag <Signature ... </Signature> and put
this to new XmlDocument.

// get signature to countersign
XmlNodeList signs =
existingXmlDocument.GetElementsByTagName("Signature",
SignedXml.XmlDsigNamespaceUrl);
XmlElement el = signs[0]; // in my test code I have only one signature
to countersign
SignedXml sig = new SignedXml();
sig.LoadXml((XmlElement)el);

XmlDocument doc = new XmlDocument(); //new empty xmlDocument - without
header and any attributes
doc.PreserveWhitespace = true;

// load obj - sognature to countersign to new created XmlDocument
System.Security.Cryptography.Xml.DataObject obj = new
System.Security.Cryptography.Xml.DataObject();

obj.LoadXml(sig.GetXml());
doc.LoadXml(obj.GetXml().OuterXml); // this load to new created
XmlDocument signature xml text

Transform t1 = new
System.Security.Cryptography.Xml.XmlDsigC14NTransform(); // my
reference have not transforms - only SignedINfo have connonicalization
transform
t1.LoadInput(doc);
System.IO.Stream s1 = (System.IO.Stream)t1.GetOutput();

// calculate hash after transform
SHA1 sha1 = SHA1.Create();
MessageBox.Show(string.Format("{0}",
Convert.ToBase64String(sha1.ComputeHash(s1))));

This is my first test
After fall, I add new transform:

Transform t2 = (Transform)CryptoConfig.CreateFromName("http://www.w3.org/2001/10/xml-exc-c14n#WithComments";);
t2.LoadInput(t1); // transform on transformed signature
System.IO.Stream s2 = (System.IO.Stream)t2.GetOutput();

MessageBox.Show(string.Format("{0}",
Convert.ToBase64String(sha1.ComputeHash(s2))));

This is what i do.
DigestValue is wrong (in code with two transformation - I have
DigestValue on t1 and t2 the same always!)
I have no more idea... but must calculate this DigestValue before i
call SignedXml.ComputeSignature and show DigestValue to my application
user.
Any other idea?
Iguana

As i told you in one of my prev. letters - check what you get from
OuterXml. It will most probably give you xml header as well.

-Valery

.

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