With the help of the MSDN site about SignedXml, I can easily verify if an XML DSig is correct. It works perfectly if the signature method sha1 was used.
However, when I receive the SignatureMethod RSA-SHA512 (http://www.w3.org/2001/04/xmldsig-more#rsa-sha512), CheckSignature() breaks with an CryptograhicException: SignatureDescription could not be created for the signature algorithm supplied.
It seems like CheckSignature() is not able to verify RSA-SHA512 signatures.
Does anyone know how to check these kind of signatures?
The code, taken from the MSDN site, is:
public static bool VerifyXml(XmlDocument doc, bool removeSignatureElement = false)
{
// Check arguments.
if (doc == null)
throw new ArgumentException("doc");
// Create a new SignedXml object and pass it the XML document class.
SignedXml signedXml = new SignedXml(doc);
// Find the "Signature" node and create a new XmlNodeList object.
XmlNodeList nodeList = doc.GetElementsByTagName("Signature", Constants.NamespaceDSig);
// Throw an exception if no signature was found.
if (nodeList.Count < 1)
{
throw new CryptographicException("Verification failed: No Signature was found in the document.");
}
// This example only supports one signature for the entire XML document. Throw an exception if more than one signature was found.
if (nodeList.Count > 1)
{
throw new CryptographicException("Verification failed: More that one signature was found for the document.");
}
// Load the first <signature> node.
signedXml.LoadXml((XmlElement)nodeList[0]);
// Check the signature and return the result.
bool signedCorrectly = signedXml.CheckSignature(); // throws the Exception!!!
return signedCorrectly;
}
The signed XML is:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Notification xmlns="http://www.xxxxxxxxxxx.xx/xxxxx">
<xenc:EncryptedData xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" Type="http://www.w3.org/2001/04/xmlenc#Content"> ... </xenc:EncryptedData>
<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
<ds:SignedInfo>
<ds:CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
<ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha512"/>
<ds:Reference URI="">
<ds:Transforms>
<ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
<ds:Transform Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments"/>
</ds:Transforms>
<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
<ds:DigestValue>WsHcyNL7Jh8HSzR9ArzTqomBkHs=</ds:DigestValue>
</ds:Reference>
</ds:SignedInfo>
<ds:SignatureValue>
pWDatSEbypIUVQR9NFmLkB9kKWjMb6rKWGFFvGqT5tOUILeDhMHUqjCRB9v/g6yYdogC9TRWouhz
...VoZAIBs7EqCbLt7RgpB4GHWc9E3qp65NaCgluw==
</ds:SignatureValue>
<ds:KeyInfo>
<ds:X509Data>
<ds:X509Certificate>
MIIG+zCCBOOgAwIBAgIHAe2+sRfTfDANBgkqhkiG9w0BAQUFADCBkTELMAkGA1UEBhMCQVQxDTAL
...tvawqBjOfkw1yeDzsDMJHfMuAcpYfrEL
</ds:X509Certificate>
</ds:X509Data>
</ds:KeyInfo>
</ds:Signature>
</Notification>