This gem provides bindings to the Win32 SSPI libraries, primarily to support Negotiate (i.e. SPNEGO, NTLM) authentication with a proxy server. Enough support is implemented to provide the necessary support for the authentication. A module is also provided which overrides Net::HTTP and adds support for Negotiate authentication to it. This implies that open-uri automatically gets support for it, as long as the http_proxy environment variable is set.