Registers – Coded record sensors – Particular sensor structure
Patent
1995-02-03
1998-02-03
Chan, Eddie P.
Registers
Coded record sensors
Particular sensor structure
235492, 902 26, G06F 1214
Patent
active
057154317
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the writing of data to non-volatile memory. Non-volatile memory is memory which retains data without electrical power being maintained. In particular, the invention relates to the writing of data to memory in transportable integrated circuit devices which are used in conjunction with terminal devices with which they are temporarily coupled for data input and output. An example of such a transportable device is the integrated circuit card (ICC), otherwise known as a "smart card".
2. Discussion of Prior Art
Smart cards are coupled by means of an interface to a terminal device whereby power, clock signals, a reset signal and serial data signals may be applied to the card. Generally the interface incorporates a set of electrical contacts for direct temporary electrical connection. However, contactless interfaces employing electromagnetic induction techniques for the application of power have been proposed. In such an arrangement clock, reset and data signals may be coupled electromagnetically or by infra-red or ultra-sonic techniques. Transportable integrated circuit devices may be embodied in tokens of other than card shape. Regardless of shape, such devices will be referred to herein as integrated circuit cards (ICCs). A difficulty with ICCs is that the writing of data to the ICC may be interfered with by disturbing the interface during writing whereby transients or failure in power, reset or clock signals may result in erroneous write.
A smart card application to which the invention is particularly applicable is in a financial value or "electronic cash" transfer system. Here, data in smart cards represents value which can be transferred on-line with banks and off-line between cards. Such a system is described in patent applications Nos. WO91/16691 and WO93/08545. It is clearly important in such applications to avoid the effects of erroneous data writing, either accidental or perhaps deliberately instigated by manipulation of power or data lines. The present invention provides a solution.
SUMMARY OF THE INVENTION
According to the invention there is provided a method of writing data to non-volatile memory in an integrated circuit device, the device having an interface for temporary connection to a terminal unit; a microprocessor; random access memory and non-volatile memory, the method consisting in allocating a first region of the non-volatile memory for data to be written, allocating a second region of non-volatile memory for write status information to be written, performing a data write operation to write data to said first region, and writing information to said second region signifying a valid data write if, and only if, the data write operation is performed satisfactorily.
In a microprocessor environment there are many copy and write procedures for transferring data and program information between regions of RAM and from RAM to EEPROM, for example, and vice versa. At the operating system level or higher there are usually verification techniques available for verifying the validity of a copy or write operation. This may involve an automatic comparison of the copied or written material with the original or, more usually, the provision of a checksum routine which adds one or more checksum bits to the data which, in accordance with a particular algorithm, provide a link to the data which can be verified to ensure that no write or copy computation has taken place. If corruption is detected the operation can be repeated until satisfactory. The present invention is not concerned with such techniques and is additional to them, where provided. However, such inbuilt techniques can be used as the basis for determining whether the write operation has been performed satisfactorily in order to write the appropriate information into the second region of memory. Thus, for example, if data is successfully written to an ICC with inbuilt write verification techniques present then the conclusion of the write process can be taken as indicati
REFERENCES:
patent: 4827115 (1989-05-01), Uchida et al.
patent: 5200600 (1993-04-01), Shinagawa
patent: 5365045 (1994-11-01), Iijima
patent: 5386539 (1995-01-01), Nishi
patent: 5390148 (1995-02-01), Saito
patent: 5475697 (1995-12-01), Katz et al.
patent: 5479637 (1995-12-01), Lisimaque et al.
Everett David B.
Jackson Keith M.
Miller Ian
Chan Eddie P.
Mondex International Limited
Nguyen Hiep T.
LandOfFree
Tamper proof security measure in data writing to non-volatile me does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tamper proof security measure in data writing to non-volatile me, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tamper proof security measure in data writing to non-volatile me will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-671482