Example Applications - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 341

Figure 13.9 Fahrsmart II contactless smart card, partially cut away. The transponder coil is
clearly visible at the lower right-hand edge of the picture (reproduced by permission of Giesecke
& Devrient, Munich)
This means that the card holder has to store money for a specific application in the
electronic purse of each closed system and no longer has direct access to this for a
different application (e.g. telephone smart card, contactless travel pass, prepaid card
for the company restaurant) (Lorenz, 1998b).
This is the result of the card technology used, since the cards that have predominated
up until now have only a memory chip and thus do not satisfy the strict security
requirements of the credit institutes for open automated financial exchange systems.
Open financial exchange systems based upon a microprocessor chip have already
been successfully introduced in the field of contact smart cards. In Germany these
systems are the Paycard from Telekom, the VISA-Cash-Karte, and the 'ec-Karte mit
Chip', the latter having the greatest customer base with approximately 50-55 million
cards in use. These cards were designed for payments of small sums and can be used
everywhere that suitable readers are available. From the point of view of the user, it
would be ideal if the cash card could be used as a ticket for local public transport. Due
to the high transaction times of contact smart cards (see Section 13.2.2.1) electronic
cash cards have also not yet been able to establish themselves as an electronic travel
pass in local public transport applications.
Various solutions have been proposed that aim to combine the user-friendliness of
contactless tickets with the security of contact exchange systems, and thus improve the
acceptance of such systems by customers (Lorenz, 1998b).
The hybrid card is the combination of a contactless smart card with an additional
contact chip on one card. There is, however, no electrical connection between the two
chips. This means that it must be possible to transfer sums of money from one chip to
the other — for example in special machines. Due to this limitation, the hybrid card
too can only be considered as a provisional solution.
The dual interface card (or Combicard, see Section 10.2.1) resulted from the combi-
nation of a contact and a contactless interface on a single card chip. This is actually the