Registers – Systems controlled by data bearing records – Credit or identification card systems
Patent
1986-10-24
1989-01-17
Pitts, Harold I.
Registers
Systems controlled by data bearing records
Credit or identification card systems
235492, G06K 500
Patent
active
047989416
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an IC card and in particular to an IC card whereby data access is restricted when improper secret identification numbers are supplied a predetermined times and the restriction can be canceled thereafter. IC cards according to the present invention include not only flat cards but also key shaped or sticklike cards. The term "secret identification number" herein refers to a particular input signal used to access the IC card and includes codes referred to as key codes or secret codes.
BACKGROUND ART
It is common in use of credit cards or identification cards that a secret identification number is supplied to confirm the identity of the card holder and the access to the information is allowed only when the proper number is supplied.
When an IC card proposed to maintain secrecy of the secret identification number is used, the allowed number of times of improper number input attempts is limited, and the card is so locked as not to be used when improper numbers are supplied predetermined times.
However, it is not desirable to disable the use of the IC card (i.e., to destroy its memory) when the secret identification number has been improperly supplied predetermined times, because it may have been caused by a mistake of the card holder, for example.
Alternatively, a scheme is conceivable, in which the number of times of improper secret identification number input attempts made with the IC card put into the input device is temporarily stored in the volatile memory contained in the IC card, and is volatilized and reset when the card is pulled out of the input device. In this case, the number of access times becomes substantially limitless by slipping the IC card into the input device repetitively. This makes ineffective the security of the IC card which is an object of limiting the improper input of the secret identification number.
If a nonvolatile memory such as a ROM is contained in the card instead of the volatile memory and the number of times of improper input attempts is stored into the nonvolatile memory permanently and cumulatively, the history of improper secret identification number input is completely stored. Since the previous number of improper input attempts is recorded, however, the restricted number is quickly reached by the number of newly counted improper input attempts, resulting in an impractical use.
DISCLOSURE OF INVENTION
An object of the present invention is to provide such a practical IC card that the number of times of improper secret identification number input attempts is recorded into a memory which cannot be rewritten or which cannot be easily rewritten and that the IC card is not broken down even if the secret identification number is improperly supplied predetermined times and the IC card can be used again by resetting the number of improper input times.
In accordance with the present invention, therefore, there is provided an IC card having at least control means and storage means, wherein the storage means comprises a storage area for storing information thereon, a secret identification number area for storing a predetermined secret identification number thereon, and an error count area for storing the number of times of improper input of the secret identification number thereon, and wherein the control means comprises comparison means for comparing a supplied secret identification number with the predetermined secret identification number stored on the secret identification number area, error count means for storing the number of times of discrepancy into the error count area when the comparison means indicates discrepancy as a result of comparison, storage area lock means for inhibiting access to the storage area when the error count means has counted a predetermined number of items, and reset means for invalidating the count of the error count area on the basis of at least one specific input signal.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic view of an IC card.
FIG. 2 shows an interface for connecting the IC car
REFERENCES:
patent: 4105156 (1978-08-01), Dethloff
patent: 4295041 (1981-10-01), Ugon
patent: 4408119 (1983-10-01), Decavele
patent: 4442345 (1984-04-01), Moller
501 Toppan Moore Company, Ltd.
Pitts Harold I.
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