dotnet/wpf · error · System.Xml.XmlException

SR.PackageSignatureCorruption

Error message

SR.PackageSignatureCorruption

What it means

ParseSigningTime parses the <SignatureProperty> section that carries the signing time of a package signature. PackageSignatureCorruption is thrown when a second <SignatureProperty> tag with the expected well-defined Id appears — the OPC signature format allows at most one such signature-time property, so duplicates mean the signature part is corrupt or non-conformant.

Solutions

  1. Remove the duplicate <SignatureProperty> element with the signing-time Id from the signature part
  2. Re-sign the package so a single conformant signing-time property is generated
  3. Validate the signature XML against the OPC digital signature schema before distribution
  4. Reject the signature as corrupt at validation time if you can't fix the source

Example fix

// before
<SignatureProperty Id="SignatureTime" Target="#id1">...</SignatureProperty>
<SignatureProperty Id="SignatureTime" Target="#id1">...</SignatureProperty> <!-- duplicate -->
// after
<SignatureProperty Id="SignatureTime" Target="#id1">...</SignatureProperty>
Defensive patterns

Strategy: try-catch

Validate before calling

bool HasSingleSigningTimeProperty(XElement sigProps) =>
    sigProps.Elements().Count(e =>
        (string)e.Attribute("Id") == "SignatureTime") <= 1;

Try / catch

try { var time = ReadSigningTime(package); }
catch (XmlException ex) when (ex.Message.Contains("corrupt")) { /* treat signature as corrupt; show warning to user */ }

Prevention

When it happens

Trigger: Signature validation on a package whose <SignatureProperties> contains more than one <SignatureProperty> element with the expected signing-time Id attribute value.

Common situations: Signature XML duplicated by buggy signing tools or merge artifacts; files concatenated/edited after signing; producers that append extra signature properties with a conflicting Id.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/63d63c745e68068c. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/WindowsBase/MS/Internal/IO/Packaging/XmlSignatureProperties.cs:165

            DateTime signingTime = DateTime.Now;
            timeFormat = null;
            
            while (reader.Read())
            {
                //Looking for <SignatureProperty> tag
                if (reader.MoveToContent() == XmlNodeType.Element
                    && (string.Equals(reader.NamespaceURI, w3cSignatureNameSpace, StringComparison.Ordinal))
                    && (string.Equals(reader.LocalName, signaturePropertyTag, StringComparison.Ordinal))
                    && reader.Depth == 2)
                {
                    //Verify Attributes
                    //Look for well-defined Id attribute and if it is present 
                    if (VerifyIdAttribute(reader))
                    {
                        //If we encounter more than one <SignatureProperty> tag with the expected
                        //id, then its an error.
                        if (signatureTimeIdFound)
                            throw new XmlException(SR.PackageSignatureCorruption);
                        else
                            signatureTimeIdFound = true;
                        
                        //VerifyTargetAttribute will return false, if the Target attribute is missing
                        //or contains an incorrect value.
                        if(VerifyTargetAttribute(reader, signatureId))
                        {
                            signingTime = ParseSignatureTimeTag(reader, out timeFormat);
                            signatureTimePropertyFound = true;
                        }
                    }
                }
                else
                    //Expected <SignatureProperty> tag not found.
                    //Look for end tag corresponding to </SignatureProperty> or 
                    //if these are other custom defined properties, then anything with
                    //depth greater than 2 should be ignored as these can be nested elements.
                    if (((string.Equals(signaturePropertyTag, reader.LocalName, StringComparison.Ordinal)

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