GB2228602A - A secure data communication system - Google Patents

A secure data communication system Download PDF

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Publication number
GB2228602A
GB2228602A GB8904443A GB8904443A GB2228602A GB 2228602 A GB2228602 A GB 2228602A GB 8904443 A GB8904443 A GB 8904443A GB 8904443 A GB8904443 A GB 8904443A GB 2228602 A GB2228602 A GB 2228602A
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GB
United Kingdom
Prior art keywords
control panel
identity code
communication system
information gathering
data communication
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.)
Withdrawn
Application number
GB8904443A
Other versions
GB8904443D0 (en
Inventor
Roy Alan Schofield
Roger William Leslie Hoyle
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shorrock Ltd
Original Assignee
Shorrock Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Shorrock Ltd filed Critical Shorrock Ltd
Priority to GB8904443A priority Critical patent/GB2228602A/en
Publication of GB8904443D0 publication Critical patent/GB8904443D0/en
Publication of GB2228602A publication Critical patent/GB2228602A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/02—Monitoring continuously signalling or alarm systems
    • G08B29/04—Monitoring of the detection circuits
    • G08B29/046—Monitoring of the detection circuits prevention of tampering with detection circuits
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B26/00—Alarm systems in which substations are interrogated in succession by a central station
    • G08B26/001—Alarm systems in which substations are interrogated in succession by a central station with individual interrogation of substations connected in parallel
    • G08B26/002—Alarm systems in which substations are interrogated in succession by a central station with individual interrogation of substations connected in parallel only replying the state of the sensor

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Alarm Systems (AREA)

Abstract

A security system includes a control panel 10 linked to a plurality of information gathering devices or interface modules 12, 14, 16, each of which receives information from an associated security loop or other sensor means (not shown) and is identifiable by the control panel 10 by a unique predetermined identity code. In order to prevent substitution of any one of the modules 12, 14, 16 by a non-functional alien module, provided by an intruder, the control panel 10 modifies the identity codes at regular or random time intervals. <IMAGE>

Description

SECURE DATA COMMUNICATION SYSTEM This invention relates to a secure date communication system especially in a security system between a central control panel and a plurality of information gathering or interface devices.
Multiplexed security control panels, in general, use various known forms of data communication to link them with subordinate interface or information gathering devices. In a first known type each device has its own unique address or identity code defined either by the system's user or predetermined for each such device. In this case the central control panel can address each device in turn or randomly, the device then sending information on the status of its inputs to the control panel and/or if necessary receiving information dispensed by the control panel.
Such a system offers a fairly high degree of security against tampering. However, they do not prevent the substitution of one interface or information gathering device for another. If an intruder having a knowledge of the system could gain access to the data communication highway between devices he could substitute an alien device which would give predetermined responses to enquiries from the control panel. In this way the system could be defeated by the substitution of false data for accurate data gathered by the security sensors. Where the device which is to be substituted has a particular address this information would be required in order to substitute an alien device. However, this knowledge is relatively easily available.
It is an object of the present invention therefore to provide secure data communication between a control panel and subordinate information gathering devices.
With this object in view the invention provides a secure data communication system comprising a central control panel linked to a plurality of information gathering devices by a data highway, each information gathering device being provided with a unique predetermined identity code, characterised in that the control panel is provided with means operative after the elapse of a predetermined time interval from activation of the control panel to assign a second unique identity code to each information gathering device linked thereto.
It will be appreciated that in this way only the control panel has a record of which information gathering device is referred to by a particular identity code. Thus it becomes relatively difficult to determine the particular identity code of any one interface device and hence the code necessary for substitution of an alien device in the system.
Preferably the control panel is operative to change the identity code of at least one information gathering device linked thereto after the elapse of a further predetermined time interval.
Advantageously the predetermined unique identity code for each device is replaced by the second identity code generated by the control panel. In this way only the control panel will know the correct identity code for each device.
Preferably the second identity code is added to the predetermined identity code to form a new two-part identity code for each device.
The invention will be described further by way of example with reference to the accompanying drawing in which the single figure is a block diagram of a preferred embodiment of a security system incorporating the invention.
Referring to the figure a security system comprises a control panel 10 and a plurality of information gathering modules or interface devices 12, 14, 16 of which three such devices are shown representatively.
Each of the interface devices 12, 14, 16 is in turn connected to a respective security loop, sensor or sensor arrangement (not shown) which is responsible for monitoring a specific area or function over which the security system has control.
The interface devices 12, 14, 16 are connected via respective connection means 18, 20, 22 to a central data communication highway 24 which serves to connect all the modules to the control panel 10. It will thus be appreciated that if any one security loop or sensor detects the presence of an intruder or any other alarm signal the interface device to which the security loop in question is connected will output an alarm signal which will be detected by the control panel and thence brought to the attention of the system's operator.
One common way of defeating such an arrangement is for an intruder to attempt to disable one or other of the security loops or the interface devices themselves. In order to overcome this possibility the control panel 10 is provided with the facility to "poll" each of the interface modules 12, 14, 16 to ascertain the status of the device and its associated input. In order to facilitate such "polling" each interface device 12, 14, 16 is given a unique identity code known as its address.
In this way the control panel can check on the status of any one particular interface device at a given time.
This function is usually controlled either by the system's operator or on a timed sequence initiated by the control panel 10 itself.
It would still be possible to overcome the system described and disable one interface device for example 12 by breaking the connection 18 between the interface device 12 and the data communication highway 24 and substituting a new, alien interface device provided by the intruder. In this case the new device would be preprogrammed to respond to control panel "polling" with a signal indicative of a correctly functioning interface device whereas it is in fact receiving no inputs from any sensor system. Thus it would be possible for an intruder to gain entry to a protected area through the security loop or sensors to which the original interface device 12 was connected. It would be appreciated however that in order to be correctly identified by the control panel 10 it is necessary in this instance for the alien interface device to respond to the correct address code.However this information is relatively easy to find as it is normally known to the system operator and others.
The invention provides a means of overcoming such an eventuality by providing the control panel 10 with programming means operative to instruct each interface device to change its respective code. This instruction can be controlled on a timed basis so as to perform this function at a specific time period after the system is switched on and can also be such as to change the address codes further at random or regular intervals thereafter. For example the instruction issued by the control panel 10 may be such as to increase or decrease the identity code of any one interface by one or more or to change the address code in total to a new number.
Furthermore the instruction may be directed to all interface devices connected to the control panel or may be directed to a specific identified individual interface device.
It will be appreciated that in this way only the control panel will have a record of which interface device has which address code. Thus it becomes difficult for an intruder to obtain the correct address code for the substituted interface device to operate correctly.
Furthermore the instruction to alter the address code may be in one of several forms. The new address code assiged to each interface device may replace completely the previously held address code or alternatively may form one segment of a new two part address code compring the original user determined address code and the new control panel determined address code. In either way it will be appreciated that it is impossible to access any one interface device in the system without going through the control panel 10.

Claims (5)

1. A secure data communication system comprising a central control panel linked to a plurality of information gathering devices by a data highway, each information gathering device being provided with a unique predetermined identity code, characterised in that the control panel is provided with means operative after the elapse of a predetermined time interval from activation of the control panel to assign a second unnique identity code to each information gathering device linked thereto.
2. A communication system as claimed in claim 1 wherein the control panel is operative to change the identity code of at least one information gathering device linked thereto after the elapse of a further predetermined time interval.
3. A communication system as claimed in claims 1 or 2 wherein the predetermined unique identity code for each device is replaced by the second identity code generated by the control panel.
4. A communication system as claimed in claims 1, 2, or 3 wherein the second identity code is added to the predetermined identity code to form a new two-part identity code for each device.
5. A secure data communication system substantially as hereinbefore described.
GB8904443A 1989-02-27 1989-02-27 A secure data communication system Withdrawn GB2228602A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8904443A GB2228602A (en) 1989-02-27 1989-02-27 A secure data communication system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8904443A GB2228602A (en) 1989-02-27 1989-02-27 A secure data communication system

Publications (2)

Publication Number Publication Date
GB8904443D0 GB8904443D0 (en) 1989-04-12
GB2228602A true GB2228602A (en) 1990-08-29

Family

ID=10652388

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8904443A Withdrawn GB2228602A (en) 1989-02-27 1989-02-27 A secure data communication system

Country Status (1)

Country Link
GB (1) GB2228602A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2666921A1 (en) * 1990-09-19 1992-03-20 Roubal Philippe High-security coding method and device for implementing this method
GB2269253A (en) * 1992-07-23 1994-02-02 Ab Automotive Electronics Ltd A security system
WO1999041725A1 (en) * 1998-02-11 1999-08-19 Scantronic Limited Electronic systems

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4581606A (en) * 1982-08-30 1986-04-08 Isotec Industries Limited Central monitor for home security system
GB2169175A (en) * 1984-12-20 1986-07-02 Reginald Conway Visual display system
US4686529A (en) * 1984-01-06 1987-08-11 Kiekert Gmbh & Co. Kommanditgesellschaft Remote-control lock system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4581606A (en) * 1982-08-30 1986-04-08 Isotec Industries Limited Central monitor for home security system
US4686529A (en) * 1984-01-06 1987-08-11 Kiekert Gmbh & Co. Kommanditgesellschaft Remote-control lock system
GB2169175A (en) * 1984-12-20 1986-07-02 Reginald Conway Visual display system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2666921A1 (en) * 1990-09-19 1992-03-20 Roubal Philippe High-security coding method and device for implementing this method
GB2269253A (en) * 1992-07-23 1994-02-02 Ab Automotive Electronics Ltd A security system
GB2269253B (en) * 1992-07-23 1995-12-13 Ab Automotive Electronics Ltd A security system
WO1999041725A1 (en) * 1998-02-11 1999-08-19 Scantronic Limited Electronic systems

Also Published As

Publication number Publication date
GB8904443D0 (en) 1989-04-12

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)