Error on property NameIDPolicy.AllowCreate when parsing legitimate SAML Request coming from Shibboleth

I am implementing a SingleSignOn solution (IdP) based on your software and having a little problem when receiving a SAMLRequest (http redirect), generated by Shibboleth.

This request contains an element: <samlp:NameIDPolicy AllowCreate="1"/>

The SAML2 standard (https://www.oasis-open.org/committees/download.php/35711/sstc-saml-core-errata-2.0-wd-06-diff.pdf lines 2186 an later) states that this is a boolean attribute. The SAML standard is only talking about the possible values "true" and "false" But the xml standard https://www.w3.org/TR/xmlschema11-2/#boolean (on which SAML2 standard is based) specifies: booleanRep ::= 'true' | 'false' | '1' | '0'

So the element sent by Shibboleth should be correct.

But when parsing the SAML request I get a error message: System.FormatException: String '1' was not recognized as a valid Boolean.

I examined the sources in github

In the ITfoxtec project this NamedIdPolicy is defined in https://github.com/ITfoxtec/ITfoxtec.Identity.Saml2/blob/662544c8e08c46bf1736bd72fcf31d06aeac1d9d/src/ITfoxtec.Identity.Saml2/Schemas/NameIDPolicy.cs

And the parsing is done in https://github.com/ITfoxtec/ITfoxtec.Identity.Saml2/blob/662544c8e08c46bf1736bd72fcf31d06aeac1d9d/src/ITfoxtec.Identity.Saml2/Util/GenericTypeConverter.cs The error message was generated by line 121: return (T)Convert.ChangeType(value, typeof(T));

I recreated the error message with this code snippet in LinqPad:

  bool? AllowCreate = GenericConvertValueToNullable<bool>("true");
  AllowCreate.Dump(); // returns boolean value true

  AllowCreate = GenericConvertValueToNullable<bool>("1"); // Triggers error in Convert.ChangeType call
  AllowCreate.Dump();

  T? GenericConvertValueToNullable<T>(string value) where T : struct
  {
    if (string.IsNullOrWhiteSpace(value))
    {
      return null;
    }
    else
    {
      return (T)Convert.ChangeType(value, typeof(T));
    }
  }

The error occurs when converting the "1" value to boolean

I also found a possible solution

Insert these lines before the Convert.ChangeType line:

if(typeof(T) == typeof(bool))
{
  int intValue;
  if(int.TryParse(value, out intValue))
  {
    if (intValue == 0 || intValue == 1)
    {
      return (T)Convert.ChangeType(intValue, typeof(bool));
    }
  }
}

In the result code, 'true' | 'false' | '1' | '0' can all be used as valid values

I tested that "7", "-1", "x" still cause the error message, as they are not valid accoording to xml standard, so thats also correct.

Is it possible that you make these changes, and release a new version of the NuGet package?

Maybe there are more boolean attributes that need complying to the xml standard?