26-05-2012, 10:35 AM
A SMART CARD BASED PREPAID ELECTRICITY SYSTEM
A SMART CARD BASED PREPAID ELECTRICITY SYSTEM.pdf (Size: 295.96 KB / Downloads: 1,411)
INTRODUCTION
In the last decade, smart cards evolved from basic memory cards to complex systems on
chips with expanding processing power. This has opened the avenue to many
applications such as financial transactions, e-commerce, physical access control, health,
and transportation services [1]. The smart card, an intelligent token, is a credit card sized
plastic card embedded with an integrated circuit chip. It provides not only memory
capacity, but computational capability as well. A smart card usually consists of a ROM or
flash memory, EEPROM and a CPU. Access to data stored on the card is under the
control of the smart card operating system.
The card operating system not only makes the smart card secure for access control, but
can also store a private key for a public key infrastructure system. Lately, the industry has
come up with 32-bit smart card processors having more than 400Kbytes of EEPROM,
and a memory management and protection unit serving as a hardware firewall. This
hardware firewall enables secure separation of adjacent applications, as well as being the
basis for secure downloading of applications. The self-containment of smart card makes
it resistant to attack as it does not need to depend upon potentially vulnerable external
resources. Because of this characteristic, smart cards are often used in several
applications which require strong security protection and authentication [2]. In addition
to information security, smart cards achieve greater physical security of services and
equipments, because a smart card restricts access to all but authorized users.
Furthermore, the smart card can be used as a credit/debit bank card which allows it to
be used effectively in e-commerce applications. The multi-application smart card, along
with the advent of open platform smart card operating systems, brings the only realistic
option for managing multiple electronic transactions nowadays. It is a cost effective
secure way to manage transactions electronically Manufacturers, issuers and users have
recognized the value of one card that handles multi-applications. A multi-application
card will be able to automatically update new services and existing applications, change
and store user profiles for each application and be accepted by a range of devices-PC,
POS, mobile phones [3]. One of the most valuable applications is in using the smart card
to buy energy. Domestic consumers could for instance buy energy, at a price based on
their previous consumption pattern, from any supplier wherever and whenever they
choose. When the customer wants to top up their gas or electricity credit they visit a
vending machine which uses the consumption data stored on their card to allocate a tariff
and calculates how much energy to offer the consumer for their money [4]. Recently, the
portal technology has been playing an increasing role in computing. Service providers are
rolling out portals to allow users to create customized web sites that display exactly the
information of interest. Corporations are rolling out portals to provide employees and
business partner's customizable access to corporate information, including news feeds
from external providers, or email, calendar and access to billing system, in addition to
other web services. For web enabled energy services, and with the advent of home
networking technology, power companies and service providers can provide value-added
services delivered to the homes, like energy management, to generate additional revenue
as well as to increase convenience and loyalty.
In this paper, we propose a novel and simple prototype of a web enabled smart card
based solution for controlling the consumption of electricity in a home environment [5].
LOGICAL FILE STRUCTURE OF A TYPICAL SMART CARD
In terms of data storage, a smart card is organized in a hierarchical form through
directories. Similar to MS-DOS, there is one master file (MF) which is like the root
directory. Under the root, we can have different files which are called elementary files
(EFs). We can also have various subdirectories called dedicated files (DFs). Every DF is
dedicated for a separate application. Under each subdirectory will be elementary files
again. The master file is implicitly selected after the smart card is reset. The useful data
that are needed for an application are located in the (EFs). EFs may be placed directly
under the MF or under a DF. Since the MF is a special sort of DF, it goes without saying
that in a single application smart card, all application files can be placed directly under
the MF. Additional DFs can be placed within an application DF. For example, a DF
placed directly under the MF could be dedicated to the ‘Corporate ID’ application. An
additional level of DFs within the application DF could contain the files for the
languages supported, such as ‘English’ and ‘Arabic’. Figure 1 shows logical view of a
smart card file structure.
The elementary file (EF) simply consists of a header and the body which stores the data.
The header of the file stores information about the file such as identification number,
description, types, size, and so on. Particularly, it stores the attribute of the file which
states the access conditions and current status. Access of the data in the file depends on
whether those conditions can be fulfilled or not.
In short, the file structure of the smart card operating system is similar to other
common operating systems such as MS-DOS and UNIX. However, in order to provide
greater security control, the attribute of each file is enhanced by adding access conditions
and file status fields in the file header. Moreover, file lock is also provided to prevent
unauthorized access. This security mechanism provides a logical protection of the smart
card [6, 7].
PREPAID ELECTRICITY
Since the last decades of the past century, scientists, researchers and public people
have been worried about energy conservation. People spend much more power than what
they actually need and that results in a huge loss of energy. Moreover, the continuous
increase in the universal energy prices has resulted in a huge economical loss. Thus we
are proposing a prepaid electricity smart card based system so people can buy specific
amount of energy to use it only when then need. People can register for this service and
charge their accounts through the Internet. The proposed system is based on an IP-based
controller called TINY, and a WATTNODE type power meter which interrupts the
controller at a regular interval based on the consumption of electricity to update the
balance based on a certain tariff. The power meter we used, interrupts the controller at a
rate of 0.75Wph, so based on the particular tariff used and the amount of power
consumption needed, the correct amount of money to be loaded into the card can be
easily calculated and programmed into the chip. The unique feature about this system is
that the electric utility in the home environment can be accessed remotely from the
supplier server due to the fact that the controller is IP-based, without the need for a PC on
site, which reduces the cost of the system drastically. People now can buy electricity in
advance, using the so-called prepaid electricity cards. The proposed prepaid smart card
can also be used to manage electricity consumption in a hotel room, as well as accessing
the room itself.Thus, people can consume only as much power as they really need. The
main role of the smart card is summarized in two things:
Authenticating the user or log in
Updating the balance in the card based on the given tariff and the electricity
consumption profile of the user stored in the smart card. See Figure 2 for the proposed
system.
As shown in Figure2, the main role of the TINY IP-based controller
is to control the flow of electricity using a solid state relay, based on
the consumption profile of the user. The TINY controller is
programmed to determine the exact amount of electricity measured by
the power meter by counting the exact number of interrupts
corresponding to the amount of electricity which the user intend to
consume. The controller also provides remote access to the electricity
supplying company server. We used a PC/SC compatible smart card
reader with ACOS1-8K smart card. The smart card here is used as a
secure token to log in to the data base of the company server, in a client
server manner, for controlling consumption of electricity as well as
toping up the smart card with additional money [8]. See Figure3 for the
authentication and the online purchasing protocol of the smart card
based prepaid electricity system.
Proposed Architecture
In this section, the overall design of the system is discussed in terms
of two approaches: two-tier architecture, and three-tier architecture [8].
Both two and three tier architectures are examples and variations of the
well-know client/server computing model. The model was proposed as
an alternative to centralized mainframe and time sharing computing. In
this model, the client interacts with the user possibly via a GUI
interface, and requests on-line services from the server. The server, on
the other hand, answers these requests and provides the services.