A user has sent me the following tip that he found while doing a test with the Demo Idp and two Service Providers (not sure if this relates specifically to this problem). Here's the description and the code correction:
However if you try to log out from the second federated service provider, you get an error message stating that “There is no signature in the incoming message”.
After analyzing a bit the code in the Demo Identity Provider, I identified the method CreateLogoutRequest in the file Logout.ashx.cs as the potential origin of the bug.
When I made the following change the test has been successful, where it says:
string xmloutput = request.GetXml().OuterXml;
It have modified:
XmlDocument requestDoc = request.GetXml();
XmlSignatureUtils.SignDocument(requestDoc, request.ID, IDPConfig.IDPCertificate);
string xmloutput = requestDoc.OuterXml;
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