GB2272560A - Data dependent coding for preventing copying of credit/ID cards. - Google Patents
Data dependent coding for preventing copying of credit/ID cards. Download PDFInfo
- Publication number
- GB2272560A GB2272560A GB9223923A GB9223923A GB2272560A GB 2272560 A GB2272560 A GB 2272560A GB 9223923 A GB9223923 A GB 9223923A GB 9223923 A GB9223923 A GB 9223923A GB 2272560 A GB2272560 A GB 2272560A
- Authority
- GB
- United Kingdom
- Prior art keywords
- data
- bits
- transitions
- code
- writing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/16—Digital recording or reproducing using non self-clocking codes, i.e. the clock signals are either recorded in a separate clocking track or in a combination of several information tracks
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K19/08—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code using markings of different kinds or more than one marking of the same kind in the same record carrier, e.g. one marking being sensed by optical and the other by magnetic means
- G06K19/10—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code using markings of different kinds or more than one marking of the same kind in the same record carrier, e.g. one marking being sensed by optical and the other by magnetic means at least one kind of marking being used for authentication, e.g. of credit or identity cards
- G06K19/12—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code using markings of different kinds or more than one marking of the same kind in the same record carrier, e.g. one marking being sensed by optical and the other by magnetic means at least one kind of marking being used for authentication, e.g. of credit or identity cards the marking being sensed by magnetic means
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
- G06Q20/00—Payment architectures, schemes or protocols
- G06Q20/30—Payment architectures, schemes or protocols characterised by the use of specific devices or networks
- G06Q20/34—Payment architectures, schemes or protocols characterised by the use of specific devices or networks using cards, e.g. integrated circuit [IC] cards or magnetic cards
- G06Q20/347—Passive cards
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07F—COIN-FREED OR LIKE APPARATUS
- G07F7/00—Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus
- G07F7/08—Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus by coded identity card or credit card or other personal identification means
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07F—COIN-FREED OR LIKE APPARATUS
- G07F7/00—Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus
- G07F7/08—Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus by coded identity card or credit card or other personal identification means
- G07F7/12—Card verification
- G07F7/125—Offline card verification
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
- G11B20/00884—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Signal Processing (AREA)
- Business, Economics & Management (AREA)
- Theoretical Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Computer Networks & Wireless Communication (AREA)
- Accounting & Taxation (AREA)
- Strategic Management (AREA)
- General Business, Economics & Management (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
Abstract
A method of recording a security code onto a recording medium eg. a credit card in which the recording of the security code (b) is dependent upon a pre-recorded, non-erasable code (a) already present on the medium. Transitions within code (a) occuring in a predetermined direction eg. from high to low determine each transition between successive bits within the security code (b). In this way security code (b) has its bit period automatically chosen by code (a) and thus prevents un-authorised copying of credit/ID cards. <IMAGE>
Description
WRITING OF A FIRST SET OF DATA
IN DEPENDENCE UPON READING A SECOND SET OF DATA
The present invention relates to a method and apparatus for writing data on a carrier and has particular, although not exclusive, relevance to magnetically encoded credit/debit cards and the like.
The invention particularly relates to a method of writing a first set of data in dependence upon reading a second type of data, both sets of data taking the form of respective digital codes carried by a common carrier, the digital code of the second set of data representing bits of constant bit period in such manner that bits of one value are represented by a different number of transitions within the code from bits of the other value, and to apparatus for carrying out such a method.
A known method of this general kind is disclosed in United States Patent US-A5,028,768. In this document the carrier takes the form of a track disposed on a substrate. The track comprises two portions, the first portion containing fixed data to be read and the second portion, when written, containing variable data. As the first portion passes over a read/write head system, the time intervals between successive transitions of the self-clocking data therein (the "second set of data") are measured and the result is used in order to establish a clock-rate for use in subsequently writing the data on the second portion of the track (the "first set of data").
Although such a system obviates the much-recognised problem of having to drive the carrier past the read/write heads at known speeds, there still remains a compromise over the security of any data written in this way. By simply reading the rate of transitions of data in the second portion, it is possible to determine the boundaries of the bits represented by the data within the second portion, thus leading to a compromised data storage system.
It is an object of the present invention to at least alleviate the abovementioned shortcomings.
According to one aspect the present invention provides a method as defined in the second paragraph above which is characterised by writing the first set of data such that transitions between successive bits therein are determined by successive transitions in a predetermined direction within the second set of data.
Because the first set of data is written at an instantaneous rate determined only by specific transitions within the second set of data, this bit rate can be determined by reading the first set of data in isolation. However, should the first set of data be fraudulently transferred to another carrier having a different second set of data, even with the same clocking rate as that on the original carrier, no match will occur and so a fraud can easily be detected.
Preferably the first set of data is erasable and the second set of data is nonerasable. Hence the data which supplies the instantaneous bit rate is always held on the carrier and so may be used as a unique reference in cases of suspected fraudulence or forgery.
According to another aspect of the present invention there is provided apparatus for writing a first set of data in dependence upon reading of a second set of data, both sets of data taking the form of respective digital codes carried by a common carrier, the digital code of the second set of data representing bits of constant bit period in such manner that bits of one value are represented by a different number of transitions within the code from bits of the other value, the apparatus comprising reading means for reading along the second set of data in order to determine the occurrence of each successive transition in a predetermined direction and writing means for writing the first set of data such that transitions between successive bits therein are determined by these successive transitions in a predetermined direction.
The present invention will now be described, by way of example only, with reference to the accompanying drawings, of which:
Figure 1 illustrates schematically a carrier bearing first and second sets of data;
Figures 2(a) and 2(b) illustrate graphically the correlation between the first and second sets of data;
Figure 3 illustrates schematically an embodiment of the present invention used to read the second set of data and to write the first set of data, and;
Figure 4 illustrates schematically an embodiment of the present invention used to verify the first set of data by reference to the second set of data.
Referring to figure 1 it will be seen that a carrier, in the present example a plastics card 2, has formed thereon on oxide layer 4. The layer 4 is liquid during its application to the card 2 and, while it is in this state, portions thereof are subjected to a magnetic field such as to orientate certain portions of the oxide in respective parallel directions, 6. The oxide layer 4 is then cured to leave these portions 6 as a track 8 having respective parallel directions possibly as a permanent feature on the card 2.
It will be understood that the above track 8 only occupies a fraction of the width of card 2 and that card 2 may support many such tracks.
Figures 2(a) and 2(b), illustrate how two tracks in the oxide layer are used to store respective sets of data. Figure 2(a) relates to a track 8 which carries the first set of data in the form of a non-erasable magnetic digital code 9.
It can be seen that the code represents, from left to right, bits of value 1001100.
The bit period is chosen to be constant along the length of the co#de 9. Also it can be seen that a bit "0" is represented by a transition within the code only at the boundaries of each bit, whereas a "1" is represented by a further transition intermediate, in this example midway between, the boundary transitions.
Figure 2B relates to a second track which carries the second set of data, in the form
of an erasable magnetic digital code 11. It can be seen how this code 11 is related to the code 9.
Transitions within code 9 occurring only in a predetermined direction, in the present example from high to low, are made to be determinant of every transition between each successive bit within code 11.
It will be appreciated that the bit values of the code 11 are themselves arbitrary, but the successive bit period are determined from code 9 in the aforementioned manner.
In this way the code 11 has its bit period automatically chosen by the code 9 and because the data embodied by code 9 is chosen to be non-erasable, i.e. a permanent feature of the track 8 on card 2, then if the erasable code 11 is fraudulently transferred to another card, then the bit transition information, i.e. bit period correlation, from the other card's non-erasable data will not match that of the fraudulently transferred erasable data and will hence fail to provide correct decoding.
Referring now to figures 3 and 4 which illustrate respectively schematic representations of systems for encoding the erasable data using the nonerasable data and for decoding, it will be seen that, with particular reference firstly to Figure 3, the card 2 bearing track 8 and the second track is passed by a detector, in the present example a magnetic read head 10. The read head 10 reads along the data on the track 8, i.e. the non-erasable data as shown in figure 2(a). Having read these non-erasable data pulses, which have all been encoded with the aforementioned constant bit period, this information is passed to a pulse generator 12.Pulse generator 12 responds to the up4odown transitions by generating respective timing pulses which are used by a signal synchronisation circuit 14 to control the spacing of the soft data, in the manner shown in figure 2(b), to be recorded. This correctly spaced soft data is fed via a magnetic head driver 16 to a writing (or encoding) head 18 which writes this soft data onto the second track (not shown) on card 2.
Concentrating now on figure 4, the decoding system includes a detector, in this example magnetic read head 20 and a magnetic read head 22 which simultaneously read both the erasable and non-erasable data from their respective tracks on card 2. Read head 20 then feeds the signal derived therefrom to pulse generator 24 which sends a clock signal, derived from the erasable data, to signal decoder 26.
The decoder 26 then reads from read head 22 the occurrence of the high-to-low transitions in the non-erasable data and compares these, using the clock signal, with the occurrence of all transitions in the erasable data. Only if the decoder 28 decides that the erasable data has been genuinely encloded for the non-erasable data does it provide a serial data output stream.
Although in the above description certain portions 6 of the oxide layer have been arranged to possess parallel orientations, and all remaining portions are shown in figure 1 to have random orientations, this need not necessarily be the case. It may be useful, in certain applications, to have the remaining portions oriented also in parallel directions, but this direction being at an angle, say 90 , to the direction of orientation of the portions 6.
It will be appreciated also that in the foregoing although reference is made to the oxide layer being formed across only part of the width of the card 2, clearly the layer 4 may extend totally across the width of the card 2 if required. Furthermore the first set of data may either be written adjacent to, or directly on top of track 8 which carries the second set of data. It will also be apparent that the tracks 8 are able not only to be deposited on the card 2, thereby effectively being disposed within a carrier rather than simply overlying the same. This provides an advantage that the tracks 8 may not be readily visible to the naked eye.
It will be apparent to those skilled in the art that, whilst in the above example the first and second sets of data are erasable data and non-erasable respectively, this is not essential. Thus, for example, both types of data may be erasable.
It will also be apparent that although up-to-down transitions in the second set of data have been described as determining the bit boundaries in the first set, down-toup transitions could alternatively be used for this purpose.
Claims (10)
1. A method of writing a first set of data in dependence upon reading a second set of data, both sets of data taking the form of respective digital codes carried by a common carrier, the digital code of the second set of data representing bits of constant bit period in such manner that bits of one value are represented by a different number of transitions within the code from bits of the other value, the method being characterised by writing the first set of data such that transitions between successive bits therein are determined by successive transitions in a predetermined direction within the second set of data.
2. A method according to claim 1 wherein the first set of data is erasable and the second type of data is non-erasable.
3. A method according to either claim 1 or claim 2 wherein the first and second sets of data are carried by respective tracks disposed on or within the common carrier.
4. A method according to any one of the preceding claims wherein the transitions within the code of the second set of data representing bits of the one value occur only at the boundaries of these bits and the transitions representing bits of the said other value occur also intermediate the boundaries of these bits.
5. A method according to any one of the preceding claims wherein the data are magnetic data.
6. A method as substantially hereinbefore described with reference to the accompanying drawings.
7. Apparatus for writing a first set of data in dependence upon reading a second set of data, both sets of data taking the form of respective digital codes carried by a common carrier, the digital code of the second set of data representing bits of constant bit period and wherein bits of one value are represented by a different number of transitions within the code from bits of the other value, the apparatus comprising:
reading means for reading along the second set of data to determine the occurrence of each successive transition in a predetermined direction
and writing means for writing the first set of data such that transitions between successive bits therein are determined by these each successive transitions in a predetermined direction.
8. Apparatus according to either Claim 7 wherein the first and second sets of data are carried by respective tracks disposed on or within the carrier.
9. Apparatus according to Claim 8 or Claim 7 wherein the reading means and writing means comprise magnetic read heads and write heads respectively.
10. Apparatus as substantially hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9223923A GB2272560B (en) | 1992-11-14 | 1992-11-14 | Writing of a second set of data in dependence upon reading a first set of data |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9223923A GB2272560B (en) | 1992-11-14 | 1992-11-14 | Writing of a second set of data in dependence upon reading a first set of data |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9223923D0 GB9223923D0 (en) | 1993-01-06 |
| GB2272560A true GB2272560A (en) | 1994-05-18 |
| GB2272560B GB2272560B (en) | 1996-07-17 |
Family
ID=10725109
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9223923A Expired - Lifetime GB2272560B (en) | 1992-11-14 | 1992-11-14 | Writing of a second set of data in dependence upon reading a first set of data |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2272560B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999024942A1 (en) * | 1997-11-10 | 1999-05-20 | Thorn Secure Science Limited | A method of labelling an article |
| WO2012041206A1 (en) * | 2010-09-30 | 2012-04-05 | 山东新北洋信息技术股份有限公司 | Magnetic recording method and apparatus |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2186732A (en) * | 1986-01-15 | 1987-08-19 | Uniqey | Improvements in encoding magnetic cards |
| US5028768A (en) * | 1988-09-27 | 1991-07-02 | Societe Anonyme Dite: Compagnie Generale D'automatise Cga Hbs | System for reading and encoding a magnetic track carried by a manually-displaced supporting document |
-
1992
- 1992-11-14 GB GB9223923A patent/GB2272560B/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2186732A (en) * | 1986-01-15 | 1987-08-19 | Uniqey | Improvements in encoding magnetic cards |
| US5028768A (en) * | 1988-09-27 | 1991-07-02 | Societe Anonyme Dite: Compagnie Generale D'automatise Cga Hbs | System for reading and encoding a magnetic track carried by a manually-displaced supporting document |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999024942A1 (en) * | 1997-11-10 | 1999-05-20 | Thorn Secure Science Limited | A method of labelling an article |
| GB2346243A (en) * | 1997-11-10 | 2000-08-02 | Thorn Secure Science Ltd | A method of labelling an article |
| GB2346243B (en) * | 1997-11-10 | 2001-04-25 | Thorn Secure Science Ltd | A method of labelling an article |
| US6832315B1 (en) | 1997-11-10 | 2004-12-14 | Thorn Secure Science Limited | Method of labelling an article |
| WO2012041206A1 (en) * | 2010-09-30 | 2012-04-05 | 山东新北洋信息技术股份有限公司 | Magnetic recording method and apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2272560B (en) | 1996-07-17 |
| GB9223923D0 (en) | 1993-01-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
| PE20 | Patent expired after termination of 20 years |
Expiry date: 20121113 |