# File lib/active_merchant/billing/integrations/sage_pay_form/helper.rb, line 44
          def form_fields
            fields['DeliveryFirstnames'] ||= fields['BillingFirstnames']
            fields['DeliverySurname']    ||= fields['BillingSurname']
            
            fields['FailureURL'] ||= fields['SuccessURL']

            crypt_skip = ['Vendor', 'EncryptKey', 'SendEmail']
            crypt_skip << 'BillingState'  unless fields['BillingCountry']  == 'US'
            crypt_skip << 'DeliveryState' unless fields['DeliveryCountry'] == 'US'
            crypt_skip << 'CustomerEMail' unless fields['SendEmail']
            
            key = fields['EncryptKey']
            @crypt ||= create_crypt_field(fields.except(*crypt_skip), key)
            
            {
              'VPSProtocol' => '2.23',
              'TxType' => 'PAYMENT',
              'Vendor' => @fields['Vendor'],
              'Crypt'  => @crypt
            }
          end