challenge (HTTPClient::SSPINegotiateAuth)

    # File lib/httpclient/auth.rb, line 493
        def challenge(uri, param_str)
          return false unless SSPIEnabled
          if param_str.nil? or @challenge[uri].nil?
            c = @challenge[uri] = {}
            c[:state] = :init
            c[:authenticator] = nil
            c[:authphrase] = ""
          else
            c = @challenge[uri]
            c[:state] = :response
            c[:authphrase] = param_str
          end
          true
        end