Cryptography – Particular algorithmic function encoding – Nbs/des algorithm
Patent
1993-09-15
1995-06-27
Cain, David C.
Cryptography
Particular algorithmic function encoding
Nbs/des algorithm
320 4, H04K 100
Patent
active
054286859
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to an IC memory card used as an external storage medium of a computer system, as well as to a method of protecting data in the IC memory card.
2. Background Art
An IC memory card is a thin card, of a size equivalent to that of a business card, and is equipped with a memory. These cards, examples of which are ROM cards, RAM cards for managing data, etc., are advantageous in that they are compact, have a high access speed and are highly reliable. Such IC memory cards have been standardized by the PCMCIA (Personal Computer Memory Card International Association), whereby their mechanical shape, pin arrangement, data read and writing timings, etc., have been stipulated. In Japan also the standardization proposals of the PCMCIA have been adopted the JEIDA (Japan Electric Industry Development Association).
An information sales system is one example of a system in which an IC memory card is adopted at an external storage medium. In an information sales system, information for sale, such as newspapers, magazines and other publications in electronic form, is transferred, via a communication line, from an information center to automatic information vending machines disposed in various areas. The information is sold by being copied onto the IC memory card.
Computer systems in which an IC memory card serves as an external storage medium have been designed in accordance with the specifications of the PCMCIA. If all of these computer systems have the same operating system (OS), data can be written/read and copied at will from any IC memory card. More specifically, the data recorded on an IC memory card can readily be read/written by any personal computer or the like having a slot for the IC memory card, and information can readily be copied to another IC card by execution of a copy command. However, the fact that data created by oneself can be freely read/written by another individual and the content of the IC card can be copied at will is extremely inconvenient insofar as maintaining the confidentiality of stored information and protecting copyrights is concerned.
Accordingly, the practice in the prior art is to convert the address data of the memory card into a different address by encryption data possessed by the computer system and store data in a storage area designated by the converted address. If this expedient is adopted, the arrangement of data in the memory card is made random so that the data cannot be read out in the correct order by another computer system, thereby making it possible to enhance the confidentiality of data and to prevent copying.
There is available a system in which an IC memory card (master card) on which prescribed data has been recorded is rented, as in the manner of video software and CD software, as well as a system in which information is sold by being recorded on an IC memory card (which becomes the master card) brought in by the purchaser, as in the manner of an automatic information vending machine. In systems of this kind it is necessary to render data meaningless if it is copied from the master card and, if the card is the master card, to allow the data recorded on the card to be viewed using any computer system (terminal device). However, a problem encountered in the conventional systems is that these requirements cannot be satisfied.
Accordingly, an object of the present invention is to provide an IC memory card that is effective in preventing copying and protecting copyrights, as well as a method of protecting data in the card.
Another object of the present invention is to provide an IC memory card, as well as a method of protecting data in the card, in which even if data is copied from a master card, the data cannot be reproduced from the card copy.
A further object of the present invention is to provide an IC memory card which, if the card is a master card, is capable of having its recorded data reproduced by any computer system, as well as a method of protecting data in the card.
Still another object of the present invent
REFERENCES:
patent: 4985920 (1991-01-01), Seki
patent: 5068894 (1991-11-01), Hoppe
patent: 5237609 (1993-08-01), Kimura
patent: 5293424 (1994-03-01), Holtey et al.
patent: 5319705 (1994-06-01), Halter et al.
Ishizaki Masayuki
Kadooka Yoshimasa
Satoh Kazuo
Touyama Mariko
Yunomura Yutaka
Cain David C.
Fujitsu Limited
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