# File lib/active_merchant/billing/integrations/valitor/helper.rb, line 63
          def signature
            raise ArgumentError, "Security number not set" unless @security_number
            parts = [@security_number, @fields['Adeinsheimild']]
            @products.sort.uniq.each do |id|
              parts.concat(["Vara_#{id}_Fjoldi", "Vara_#{id}_Verd", "Vara_#{id}_Afslattur"].collect{|e| @fields[e]})
            end if @products
            parts.concat(%w(VefverslunID Tilvisunarnumer SlodTokstAdGjaldfaera SlodTokstAdGjaldfaeraServerSide Gjaldmidill).collect{|e| @fields[e]})
            Digest::MD5.hexdigest(parts.compact.join(''))
          end