GB2272092A - Data storage and recovery devices - Google Patents
Data storage and recovery devices Download PDFInfo
- Publication number
- GB2272092A GB2272092A GB9224534A GB9224534A GB2272092A GB 2272092 A GB2272092 A GB 2272092A GB 9224534 A GB9224534 A GB 9224534A GB 9224534 A GB9224534 A GB 9224534A GB 2272092 A GB2272092 A GB 2272092A
- Authority
- GB
- United Kingdom
- Prior art keywords
- data
- sentinel
- storage medium
- writing
- enabled
- 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
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Classifications
-
- 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
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
Abstract
Encrypted data is stored on a magnetic stripe on a card, the data being stored in separate tracks, each containing a number of characters. By storing encrypted data within a predetermined number of data character locations between a 'start sentinel' character and an 'end sentinel' character, a value appearing somewhere in the encrypted data corresponding to a start sentinel or an end sentinel can be recognised as ordinary data, not a sentinel.
Description
DATA STORAGE AND RECOVERY DEVICES
This invention relates to data storage and recovery devices and particularly, but not exclusively, to the storage of data in encrypted form on a magnetic recording medium and to the recovery of such data by reading the recording.
A standard ISO character set is conventionally used for the storage of data on a conventional magnetic stripe card. The normal format of data on each of the three 'tracks' of such a magnetic card is as follows.
All three tracks contain a number of characters. The first character on each track is called a start sentinel and is used to indicate the start position of data on the track. The start sentinel is followed by a variable number of data characters. After the data characters comes an end sentinel character, which indicates the end position of data on the track. The end sentinel is followed by a longitudinal redundancy check (LRC) character which enables the card reader to detect data corruption.
There can be only one start sentinel and one end sentinel written on a track. This is to ensure that the card reader can correctly identify the start and end positions of the track data.
For this reason, data characters cannot use the start and end sentinel character values.
A problem has arisen in the circumstance that the data is encrypted prior to recordal on the magnetic stripe, for example by using the
DES encryption algorithm. The encrypted data may itself happen to contain values which are used to denote the start and end sentinels.
A possible solution would be to employ an encryption algorithm that does not generate the values corresponding to the start and end sentinels, but this would be inconvenient and restrictive.
According to one aspect of the invention a method of storing data on a data storage medium in encrypted form comprises writing a start sentinel on the storage medium, writing the encrypted data, and writing an end sentinel on the storage media at a predetermined number of data character locations from said start sentinel.
The data storage medium is preferably a magnetic medium, and most preferably is in the form of a magnetic stripe on a card.
According to a second aspect of the invention a writing system for writing data on a data storage medium comprises writing means for writing on a data storage medium, means for generating a start sentinel, for supply to the writing means to write a start sentinel on the storage medium, means for encrypting a data package and for supplying the encrypted data package to the writing means, and means for generating an end sentinel at a predetermined number of character locations from said start sentinel and supplying the end sentinel to the writing means.
According to a third aspect of the invention a method of recovering data from a data storage medium comprises looking for a start sentinel, on detection of a start sentinel reading encrypted data which follows the start sentinel, looking for the occurrence of an end sentinel at a location of the storage medium which is a predetermined distance from said start sentinel, and terminating the reading of said data on detection of said end sentinel, the occurrence of any character in the encrypted data that happens to correspond to either a start sentinel or an end sentinel being treated as an ordinary data character.
According to a fourth aspect of the invention a data recovery apparatus for recovering data from a data storage medium on which encrypted data has been written, comprises a reading means for reading the data storage medium, start sentinel detection means responsive to the reading means to detect, when enabled, a start sentinel, data handling means responsive to the reading means for receiving encrypted data from the reading means when the data handling means is enabled, the data handling means being enabled only in response to detection of a start sentinel by the start detection means when enabled, and end sentinel detection means responsive to the reading means to detect, when enabled, an end sentinel, the arrangement being such that the end sentinel detection means is enabled only after a predetermined period following detection of a start sentinel, by the enabled start sentinel detection means, and the start sentinel detection means is disabled following detection of a start sentinel and is enabled again only following detection of an end sentinel by the enabled end sentinel detection means.
The data handling means may be arranged to decrypt the encrypted data or may transmit the data in encrypted form to other equipment.
It will be appreciated that when encrypted data is read from a data storage medium using the method and apparatus in accordance with the invention, it does not matter that a value corresponding to a start sentinel or an end sentinel appears somewhere in the block of data, because such a value is treated as ordinary data, not as a sentinel.
This enables the full range of values to be used for the encrypted data.
The data storage medium may be part of an identity device such as a card.
Each identity device preferably has a unique serial ID number which is embossed or printed on the identity device. This serial number is preferably arranged always to form a part of the encrypted data stored on the magnetic stripe of the identity device. This feature allows the detection of replication of data to another identity device by comparison of embossed and stored serial numbers.
Claims (11)
1. A method of storing data on a data storage medium in encrypted form comprising writing a start sentinel on the storage medium, writing the encrypted data, and writing an end sentinel on the storage medium at a predetermined number of data character locations from said start sentinel.
2. A method of recovering data from a data storage medium comprising looking for a start sentinel, on detection of a start sentinel reading encrypted data which follows the start sentinel, looking for the occurrence of an end sentinel at a location of the storage medium which is a predetermined distance from said start sentinel, and terminating the reading of said data on detection of said end sentinel, the occurrence of any character in the encrypted data that happens to correspond to either a start sentinel or an end sentinel being treated as an ordinary data character.
3. A method as claimed in claim 1 or claim 2 in which the data storage medium is a magnetic medium.
4. A method as claimed in any one of the preceding claims in which the data storage medium is part of an identity device.
5. A method as claimed in claim 4 in which the identity device bears a serial ID number separately from data on the storage medium.
6. A method as claimed in claim 5 in which the serial ID number forms a part of the encrypted data stored on the data storage medium.
7. A method as claimed in any one of the preceding claims in which the storage medium is in the form of a magnetic stripe on a card.
8. A writing system for writing data on a data storage medium comprising writing means for writing on a data storage medium, means for generating a start sentinel, for supply to the writing means to write a start sentinel on the storage medium, means for encrypting a data package and for supplying the encrypted data package to the writing means, and means for generating an end sentinel at a predetermined number of character locations from said start sentinel and supplying the end sentinel to the writing means.
9. A data recovery apparatus for recovering data from a data storage medium on which encrypted data has been written, comprising a reading means for reading the data storage medium, start sentinel detection means responsive to the reading means to detect, when enabled, a start sentinel, data handling means responsive to the reading means for receiving encrypted data from the reading means when the data handling means is enabled, the data handling means being enabled only in response to detection of a start sentinel by the start detection means when enabled, and end sentinel detection means responsive to the reading means to detect, when enabled, an end sentinel, the arrangement being such that the end sentinel detection means is enabled only after a predetermined period following detection of a start sentinel, by the enabled start sentinel detection means, and the start sentinel detection means is disabled following detection of a start sentinel and is enabled again only following detection of an end sentinel by the enabled end sentinel detection means.
10. A data recovery apparatus as claimed in claim 9 in which the data handling means is adapted to decrypt the encrypted data.
11. An identity device bearing data stored according to the method of any one of claims 1 to 6.
11. A data recovery apparatus as claimed in claim 9 in which the data handling means is adapted to transmit the data in encrypted form to other equipment.
12. An identity device bearing data stored according to the method of any one of claims i to 7.
Amendments to the claims have been filed as follows 1. A method of storing data on a magnetic data storage medium in encrypted form comprising writing a start sentinel on the storage medium, writing the encrypted data, and writing an end sentinel on the storage medium at a predetermined number of data character locations from said start sentinel.
2. A method of recovering data from a magnetic data storage medium comprising looking for a start sentinel, on detection of a start sentinel reading encrypted data which follows the start sentinel, looking for the occurrence of an end sentinel at a location of the magnetic storage medium which is a predetermined distance from said start sentinel, and terminating the reading of said data on detection of said end sentinel, the occurrence of any character in the encrypted data that happens to correspond to either a start sentinel or an end sentinel being treated as an ordinary data character.
3. A method as claimed in claim 1 or.2 in which the magnetic data storage medium is part of an identity device.
4. A method as claimed in claim 3 in which the identity device bears a serial ID number separately from data on the storage medium.
5. A method as claimed in claim 4 in which the serial ID number forms a part of the encrypted data stored on the data storage medium.
6. A method as claimed in any one of the preceding claims in which the magnetic storage medium is in the form of a magnetic stripe on a card.
7. A writing system for writing data on a magnetic data storage medium comprising writing means for writing on a data storage medium, means for generating a start sentinel, for supply to the writing means to write a start sentinel on the storage medium, means for encrypting a data package and for supplying the encrypted data package to the writing means, and means for generating an end sentinel at a predetermined number of character locations from said start sentinel and supplying the end sentinel to the writing means.
8. A data recovery apparatus for recovering data from a magnetic data storage medium on which encrypted data has been written, comprising a reading means for reading the data storage medium, start sentinel detection means responsive to the reading means to detect, when enabled, a start sentinel, data handling means responsive to the reading means for receiving encrypted data from the reading means when the data handling means is enabled, the data handling means being enabled only in response to detection of a start sentinel by the start detection means when enabled, and end sentinel detection means responsive to the reading means to detect, when enabled, an end sentinel, the arrangement being such that the end sentinel detection means is enabled only after a predetermined period following detection of a start sentinel, by the enabled start sentinel detection means, and the start sentinel detection means is disabled following detection of a start sentinel and is enabled again only following detection of an end sentinel by the enabled end sentinel detection means.
9. A data recovery apparatus as claimed in claim 8 in which the data handling means is adapted to decrypt the encrypted data.
10. A data recovery apparatus as claimed in claim 8 in which the data handling means is adapted to transmit the data in encrypted form to other equipment.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB929222855A GB9222855D0 (en) | 1992-10-31 | 1992-10-31 | Data storage and recovery devices |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9224534D0 GB9224534D0 (en) | 1993-01-13 |
| GB2272092A true GB2272092A (en) | 1994-05-04 |
| GB2272092B GB2272092B (en) | 1995-06-28 |
Family
ID=10724344
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB929222855A Pending GB9222855D0 (en) | 1992-10-31 | 1992-10-31 | Data storage and recovery devices |
| GB9224534A Expired - Fee Related GB2272092B (en) | 1992-10-31 | 1992-11-24 | Data storage and recovery devices |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB929222855A Pending GB9222855D0 (en) | 1992-10-31 | 1992-10-31 | Data storage and recovery devices |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB9222855D0 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997027565A1 (en) * | 1996-01-25 | 1997-07-31 | Central Research Laboratories Limited | Method of identifying a data carrier |
| WO1999024942A1 (en) * | 1997-11-10 | 1999-05-20 | Thorn Secure Science Limited | A method of labelling an article |
| EP2083376A1 (en) * | 2006-09-11 | 2009-07-29 | Future Technology Institute Corporation | Counterfeit card detecting system, authentication judgment information writing device, and counterfeit card detecting device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1306116A (en) * | 1969-04-14 | 1973-02-07 |
-
1992
- 1992-10-31 GB GB929222855A patent/GB9222855D0/en active Pending
- 1992-11-24 GB GB9224534A patent/GB2272092B/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1306116A (en) * | 1969-04-14 | 1973-02-07 |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997027565A1 (en) * | 1996-01-25 | 1997-07-31 | Central Research Laboratories Limited | Method of identifying a data carrier |
| AU710207B2 (en) * | 1996-01-25 | 1999-09-16 | Central Research Laboratories Limited | Method of identifying a data carrier |
| US6179211B1 (en) | 1996-01-25 | 2001-01-30 | Central Research Laboratories Limited | Method of identifying a data carrier |
| 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 |
| JP2002511174A (en) * | 1997-11-10 | 2002-04-09 | ソーン セキュア サイエンス リミティド | How to label a product |
| US6832315B1 (en) | 1997-11-10 | 2004-12-14 | Thorn Secure Science Limited | Method of labelling an article |
| EP2083376A1 (en) * | 2006-09-11 | 2009-07-29 | Future Technology Institute Corporation | Counterfeit card detecting system, authentication judgment information writing device, and counterfeit card detecting device |
| JPWO2008032351A1 (en) * | 2006-09-11 | 2010-01-21 | 株式会社フューチャーテクノロジー研究所 | Counterfeit card discrimination system, authenticity judgment information writing device, and counterfeit card discrimination device |
| EP2083376A4 (en) * | 2006-09-11 | 2011-03-02 | Future Technology Inst Corp | Counterfeit card detecting system, authentication judgment information writing device, and counterfeit card detecting device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9224534D0 (en) | 1993-01-13 |
| GB2272092B (en) | 1995-06-28 |
| GB9222855D0 (en) | 1992-12-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20031124 |