Chip card

Details Chip card Chip card

1998-09-14

2000-05-09

Lee, Michael G

Registers

Records

Conductive

235380, 235451, G06K 1906

Patent

active

060591919

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a chip card having a card body and a semiconductor chip which is accommodated within the card body and on which a control circuit and a semiconductor memory device, which is electrically coupled to the control circuit, are constructed in an integrated manner, which control circuit is supplied with a supply voltage generated by a voltage supply circuit and with a clock generated by a clock supply circuit, which is arranged separately from the control circuit, the supply voltage having an operating voltage value lying within predetermined operating voltage limits, and the supply clock having an operating clock value lying within predetermined operating clock limits.
2. Description of the Related Art
The possible applications of chip cards, which are generally constructed in the check card format, have become extremely diverse, because of a high functional flexibility, and are increasing further with the rising computing power and memory capacity of the available integrated circuits. In addition to the currently typical fields of application of such chip cards in the form of health insurance cards, flex-time registration cards, telephone cards, the future will yield, in particular, applications in electronic payment transactions, in computer-controlled access monitoring, in protected data storage and the like. When microcontrollers are used on chip cards, it is necessary in most cases to observe very high security requirements, in order effectively to prevent unauthorized access to confidential data about the chip card holder or manipulation of amounts of money. In the previously known chip cards, protective elements are therefore incorporated, which can be subdivided, in terms of the mode of operation, into passive and active protective mechanisms, and which are described, for example, in the handbook having the title "Chipkarten" [chip cards], Carl Hanser Verlag, 1995, pages 208-213.
Passive protective mechanisms are essentially based directly on the technology of semiconductor manufacture. For example, in order to check the chips during the semiconductor production and in order to execute the internal test programs, all microcontrollers have a so-called test mode, in which the semiconductor circuits can be tested still on the wafer or in the module at the manufacturer's. This test mode allows modes of access to the memory which are strictly forbidden later, with the result that the changeover from the test mode into the user mode must be tendered irreversible. This is generally effected using polysilicon fuses on the chip. Furthermore, it is known to arrange the internal buses on the chip, which connect the processor to three different memory types ROM, EEPROM and RAM, are thus not led to the outside and with which thereafter contact cannot be made even using very complicated methods, in a confused and many times mutually interchanged position via encoded arrangements of the individual bus lines. There is therefore no possibility for an unauthorized user to listen in to, or to influence, the address, data or control bus of the microcontroller and thereby to read out memory contents. Furthermore, by accommodating the semiconductor memory not in the uppermost and thus most easily accessible layers but in the lower silicon layers, it is made impossible or more difficult to read out the content of a read-only memory bit by bit using an optical microscope. A further risk is represented by the analysis of electrical potentials on the chip during operation. Given a sufficiently high sampling frequency, there is the possibility of measuring charge potentials, that is to say voltages, on very small crystal regions and in this way of drawing conclusions about the data contents of the semiconductor memory of the random access type (RAM) during operation, and hence of obtaining access to confidential data about the chip card holder. This can be prevented in a certain way by means of an additional metallization layer over the corresponding

REFERENCES:
patent: 3699311 (1972-10-01), Dunbar
patent: 5471039 (1995-11-01), Irwin, Jr. et al.
patent: 5475205 (1995-12-01), Behm et al.
Handbuch "Chipkarten", Carl Hanser Verlag, 1995, pp. 208-213. Month Missing .

Affiliated with

Also associated with

Rating

Chip card does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Chip card, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chip card will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1056421