Smart cards!!!
Sunday, August 10, 2008 12:06Everyone has seen a smart card in some form, may be its your driving license, your banking card, or your STB card. smart cards are being used in daily life. Now, why smart cards? is it just a fancy stuff or just some data holder or data holder with security.
yes, security is one of the major aspects of smart card. Okay, consider this as an introduction to smart cards.
Vcc is the supply voltage that drives the chips and is generally 5 volts. It should be noted however that in the future we are likely to see a move towards 3 volts taking advantage of advanced semiconductor technology and allowing much lower current levels to be consumed by the integrated circuit. Vss is the substrate or ground reference voltage against which the Vcc potential is measured. Reset is the signal line that is used to initiate the state of the integrated circuit after power on.This is in itself an integral and complex process that we shall describe later in more detail.
The clock signal is used drive the logic of the IC and is also used as the reference for the serial communications link. There are two commonly used clock speeds 3.57 MHZ and 4.92 MHZ. The lower speed is most commonly used to date in Europe but this may change in the future. One may be tempted to ask why these strange frequencies were chosen, why not just a straight 5 MHZ. The reason lies in the availability of cheap crystals to form the clock oscillator circuits. Both of these frequencies are used in the television world for the colour sub carrier frequency. The PAL system operates using 4.92 MHZ whilst the 3.57 MHZ is used by the American NTSC standard. The Vpp connector is used for the high voltage signal that is necessary to program the EPROM memory. Last, but by no means least is the serial input/output (SIO) connector. This is the signal line by which the chip receives commands and interchanges data with the outside world. This is also a fairly complex operation and will be the subject of a more detailed discussion where symbols such as T0 and T1 will be fully explained.
At the current time there are two communication protocols that are in general use,
The T = 0 protocol is the predominant protocol in France and was the only protocol specified in ISO 7816 -3. In 1992 ISO standardised the T = 1 protocol as amendment 1 to ISO 7816 - 3. Clearly the IC card and the interface device must operate with a common protocol. The method by which they achieve a common optimum configuration has been the subject of much discussion over the last few years. This principle is intended to be achieved by the use of protocol type selection (PTS). This is effectively a special command sent from the interface device to the ICC after the answer to reset. In order to maintain backward compatibility with existing commercial systems that may only be capable of handling the T=0 communication protocol some changes are necessary to the original ISO 7816-3 standard. A new concept is proposed which identifies the principle of two modes of operation,
An ICC that operates in a negotiable mode may have its communication protocol changed by the use of the PTS command. An ICC that operates in the specific mode cannot accept a PTS command but may be put into the negotiable mode by a further assertion of the reset command.
Although the ICC indicates to the interface device (by means of TA2) its capability to change to the
negotiable mode, an existing device in the market place may however be unaware of these changes and therefore will not be prepared to reset the card.
To Be Continued….
Quote of the Day:"When due process fails us, we really do live in a world of terror." - JC Denton
