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METHOD OF AND APPARATUS FOR PROVIDING A PROGRAMMABLE CLOCK FREQUENCY IN A SMART CARD INTERFACE

IP.com Disclosure Number: IPCOM000010154D
Publication Date: 2002-Oct-28
Document File: 16 page(s) / 1M

Publishing Venue

The IP.com Prior Art Database

Abstract

Generally, a smart card has a particular operating clock frequency that is selected before it is issued. The predominant frequency mode selected for smart cards is, for example, 4.9152 MHz in Japan and 3.579545 MHz in the U.S.A. and France. A prior art smart card write/reader therefore, has a clock generator implemented by an oscillator having a fixed frequency of 3.579545 MHz. The single-frequency clock generator scheme stated above is undesirable from the standpoint of applicable range. Specifically, when a smart card write/reader whose clock generator oscillates at a certain fixed clock frequency is loaded with a smart card that operates at a different frequency, the write/reader cannot read data out of the smart card at all so that the processing apparatus is practically useless. Another consideration relating to the clock signal is that, under some conditions, the duty cycle of the externally applied clock signal may vary, and parasitic effects may cause random transients (glitches) in the externally applied clock signal. The result of such duty cycle variation and/or glitches in the externally applied clock signal may be that the application program being run by the MPU does not execute properly, causing uncontrolled malfunctioning of the smart card. Another problem is the generation and application of selected clock frequencies in a smart card write/reader without exchanging components. When the prior art smart card write/reader whose clock generator oscillates at a certain fixed clock frequency is loaded with a smart card that operates at a different frequency, the write/reader cannot read data out of the smart card at all so that the processing apparatus is practically useless. What is needed is a way to generate and apply one of a selection of clock frequencies such that a given smart card reader can be utilized by smart cards of different operating frequencies. Also needed is a way to insure that random transients (glitches) and duty cycle variations do not occur when switching the externally applied clock signal from one clock frequency to another in a smart card write/reader as any variations in duty cycle or glitches present on the applied clock signal must be avoided. The result of any clock irregularities may be that the application program being run by the MPU does not execute properly, causing uncontrolled malfunctioning of the smart card. Thus, another need is a way to insure that there are no duty cycle variations and/or glitches present in the applied clock signal, in particular when the clock generator switches from one clock frequency to another.

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METHOD OF AND APPARATUS FOR PROVIDING A

PROGRAMMABLE CLOCK FREQUENCY IN A SMART CARD

INTERFACE

Background

A smart card is a credit card sized piece of plastic with an integrated circuit chip embedded in it.  Data placed on the chip can be read and updated when the card is inserted into a terminal or, in some cases, when it is simply placed in the proximity of a radio-frequency based smart card device.

Applications include:

  • Prepayment for services. (prepaid phone cards)
  • Digital cash. (i.e., credit, debit and e-purse cards, ATM card, vending machines)
  • Loyalty cards for discounts.
  • Access control to buildings, computers or other secure areas.
  • Storing a patient's medical records.

There are two basic types of cards that are often called smart cards, and some are decidedly smarter than others.  The first is a simple memory card that, like the familiar magnetic stripe card, stores data.  Unlike a magnetic stripe card, it can write new data over existing data many times and it can store, depending on the card, up to 32 Kbytes of information.  While memory cards qualify as smart cards, at least in comparison with magnetic stripe technology, the integrated circuit card is the truly intelligent member of this family.  It is really a tiny computer, complete with an operating system, and the ability to run multiple applications from the same chip.  Because a smart card is programmable, applications and data can be downloaded onto it for a wide variety of uses, even on a single card.  Because it has storage and processing capability, it can add or subtract value, like a debit card, a pre-paid phone card, or a loyalty card.  The ability to act as a computer also brings security features not found in credit cards.  Unlike the archetypal credit cards and their magnetic stripes, smart cards have an actual processor built right in and can be written to an infinite number of times.

Smart cards require a high level of security, ensuring no one can "hack" the value off a card, or otherwise put unauthorized information on the card. Because it is hard to get at the data without authorization, and because it fits into one's pocket, a smart card is uniquely appropriate for secure and convenient data storage.

On the software side of security, smart cards must ensure both authentication and authorization.  The holder of a smart card is authenticated, via a PIN or other mechanism, to conduct certain types of business. Authorization refers to the types of information or activities the authenticated

cardholder is entitled to.  In the situation that the data you wish to access isn't on the card itself, a smart card can also do certification.  In this process, the smart card produces a digital authentication certificate that allows the authenticated individual to access the described data.  This is anticipated to be an increasingly interesting application when smart cards are used to access information on corporate intranets or on the Internet. 

The largest smart card markets...