Title:
ELECTRONIC LOCK SYSTEM
United States Patent 3848229
Abstract:
An electronic lock system in which a coded data word is stored in a key and, upon insertion of the key into a lock, compared with a master code, a positive comparison providing actuation of the lock. Lack of correspondence between the key code and the master code causes actuation of an alarm and can also cause seizure of the key in the lock. Digital circuitry is employed in both the key and lock and is configured to permit easy alteration of the stored code to greatly enhance system security. Only four interconnections need couple the key to the lock and the stored key code can be selectively altered to further enhance system security.
US Patent References:
Identification system
James - November 1959 - 2914746
Security system
O'Gorman - October 1964 - 3154761
Information card
Nugent - April 1966 - 3245697
Status-indicating system
Goldman - July 1968 - 3394246
Vending machine for credit card purchasing
Mathews - September 1968 - 3401830
Identification system
James - November 1959 - 2914746
Security system
O'Gorman - October 1964 - 3154761
Information card
Nugent - April 1966 - 3245697
Status-indicating system
Goldman - July 1968 - 3394246
Vending machine for credit card purchasing
Mathews - September 1968 - 3401830
Inventors:
Perron, Robert R. (Beverly, MA)
Fowler, John T. (Winthrop, MA)
Fowler, John T. (Winthrop, MA)
Application Number:
05/273529
Publication Date:
11/12/1974
Filing Date:
07/20/1972
View Patent Images:
Export Citation:
Assignee:
Arthur D. Little, Inc. (Cambridge, MA)
Primary Class:
Other Classes:
902/4
International Classes:
G07C9/00; H04Q9/00
Field of Search:
340/149A
US Patent References:
Primary Examiner:
Pitts, Harold I.
Attorney, Agent or Firm:
Stein, And Orman
Parent Case Data:
REFERENCE TO RELATED APPLICATIONS
This application is a continuation of Ser. No. 132,671 filed Apr. 9, 1971 and now abandoned.
Claims:
We claim
1. An electronic lock system comprising:
2. An electronic lock system according to claim 1 wherein:
3. An electronic lock system according to claim 1 wherein said lock includes means operative after comparison of said key code with said master code for reentering a key code into the electronic data memory of said key.
4. An electronic lock system according to claim 1 wherein said lock includes:
5. An electronic lock system according to claim 2 wherein said lock includes means within said receptacle for preventing removal of said key therefrom during comparison of said key code with said master code.
6. An electronic lock system according to claim 5 wherein said removal preventing means is operative in response to said second output indication from said comparison means to capture said key in said lock receptacle upon non-identity between said key code and master code.
7. An electronic lock system according to claim 2 wherein said comparison means is operative to compare said key code and said master code on a bit by bit basis and to provide said second signal indication upon detection of a bit of said key code which does not compare with the corresponding bit of said master code.
8. An electronic lock system according to claim 1 wherein said key data memory is of a data capacity to store predetermined data in addition to said key code;
9. An electronic lock system comprising:
10. An electronic lock system according to claim 9 wherein:
11. An electronic lock system according to claim 10 wherein said lock comparing means is also operative to provide said second signal indication in response to non-comparison between said enable code and said predetermined code.
12. An electronic lock system comprising:
13. An electronic lock system according to claim 12 wherein:
14. An electronic lock system according to claim 13 wherein said logic means includes:
15. An electronic lock system according to claim 14 wherein said timing means includes means for providing first clock pulses and second clock pulses delayed with respect to said first clock pulses by a predetermined amount, said first clock pulses being employed to control data bit transitions in said logic circuitry, said second clock pulses being employed to control data bit comparisons in said logic circuitry.
16. An electronic lock system according to claim 14 wherein said lock includes:
17. An electronic lock system according to claim 14 wherein said lock includes:
18. An electronic lock system according to claim 12 wherein said key shift register is of a data capacity to store a multiple bit code longer than said key code, said key code being stored in said shift register as part of the stored code.
19. An electronic lock system comprising:
20. An electronic lock system according to claim 19 wherein:
21. An electronic lock system comprising:
22. An electronic lock system according to claim 21 wherein:
23. An electronic lock system comprising:
1. An electronic lock system comprising:
2. An electronic lock system according to claim 1 wherein:
3. An electronic lock system according to claim 1 wherein said lock includes means operative after comparison of said key code with said master code for reentering a key code into the electronic data memory of said key.
4. An electronic lock system according to claim 1 wherein said lock includes:
5. An electronic lock system according to claim 2 wherein said lock includes means within said receptacle for preventing removal of said key therefrom during comparison of said key code with said master code.
6. An electronic lock system according to claim 5 wherein said removal preventing means is operative in response to said second output indication from said comparison means to capture said key in said lock receptacle upon non-identity between said key code and master code.
7. An electronic lock system according to claim 2 wherein said comparison means is operative to compare said key code and said master code on a bit by bit basis and to provide said second signal indication upon detection of a bit of said key code which does not compare with the corresponding bit of said master code.
8. An electronic lock system according to claim 1 wherein said key data memory is of a data capacity to store predetermined data in addition to said key code;
9. An electronic lock system comprising:
10. An electronic lock system according to claim 9 wherein:
11. An electronic lock system according to claim 10 wherein said lock comparing means is also operative to provide said second signal indication in response to non-comparison between said enable code and said predetermined code.
12. An electronic lock system comprising:
13. An electronic lock system according to claim 12 wherein:
14. An electronic lock system according to claim 13 wherein said logic means includes:
15. An electronic lock system according to claim 14 wherein said timing means includes means for providing first clock pulses and second clock pulses delayed with respect to said first clock pulses by a predetermined amount, said first clock pulses being employed to control data bit transitions in said logic circuitry, said second clock pulses being employed to control data bit comparisons in said logic circuitry.
16. An electronic lock system according to claim 14 wherein said lock includes:
17. An electronic lock system according to claim 14 wherein said lock includes:
18. An electronic lock system according to claim 12 wherein said key shift register is of a data capacity to store a multiple bit code longer than said key code, said key code being stored in said shift register as part of the stored code.
19. An electronic lock system comprising:
20. An electronic lock system according to claim 19 wherein:
21. An electronic lock system comprising:
22. An electronic lock system according to claim 21 wherein:
23. An electronic lock system comprising:
Description:
FIELD OF THE INVENTION
This invention relates to lock systems and more particularly to an electronic lock system employing active digital electronic circuitry in both the key and lock.
BACKGROUND OF THE INVENTION
Electronic locks have been proposed in which an electronic circuit in a lock is energized to activate the lock by use of a key containing circuitry cooperative with the lock circuit. The circuitry employed in a key has generally been of a type in which a plurality of coded interconnections are provided to appropriately energize an associated lock circuit. Such key circuitry, however, usually contains a fixed code which is alterable only by rewiring of the key circuit. There is little versatility of coding in such conventional systems. In addition, the configuration of the key circuit can be ascertained by appropriate analysis and the code thereby duplicated. As a further disadvantage, such keys usually require a relatively large number of interconnections with the lock, with attendant increase in system cost and complexity.
SUMMARY OF THE INVENTION
In accordance with the present invention, a highly reliable and secure electronic lock system is provided in which active data storage means are provided within a key containing a readily alterable coded data word corresponding to a master code stored in an associated lock circuit. Upon insertion of the key into the lock, the data stored in the key is compared with a master code in the lock, identity therebetween causing actuation of the lock. In the event that there is not exact comparison between the master code and the key code, an alarm can be actuated and the key seized within the lock to prevent its removal therefrom. By immediate actuation of an alarm in the event of detection of one or more incorrect bits of the key code, there is little opportunity to attempt duplication of the key code and thereby materially enhancing the security of the system. Analysis of the data storage circuitry within the key will not reveal the data code stored therein and even if the stored data were read out by interrogation of the key, the data can be selectively coded such that it would be, in practice, substantially impossible to analyze and decode the data content thereof.
In a typical embodiment of the invention, the key contains a multiple bit shift register for storing the key code and is typically of the integrated circuit type having extremely low energy requirements. Power is provided by a small battery source located within the key. Alternatively, the shift register can be of the nonvolatile type requiring no external power, in which case no battery need be employed. Only four connections are required between the key and the associated lock; one for transferring data from the key to the lock, one for transferring data from the lock back into the key, a ground connection and a clock line. Such connection can be made by various electrical contact elements suited to particular system requirements or, as an alternative, connection can be made inductively.
DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a simplified block diagram representation of a lock system according to the invention;
FIG. 2 is a block diagram of an alternative key circuit embodying the invention;
FIG. 3 is a partial block diagram of an alternative lock circuit embodying the invention;
FIG. 4 is a more detailed block diagram of a lock system according to the invention; and
FIG. 5 is a pictorial view, partly in section, illustrating a typical key configuration embodying the invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1 there is shown an electronic key 10 having a memory 12 powered by a suitable energy source such as a battery 14. The memory is typically a shift register of the low power type constructed by monolithic integrated circuit techniques and is, therefore, of extremely small physical configuration capable of being readily mounted in a small key member. The battery is typically a low power mercury battery also adapted for mounting in the key member and capable of energizing memory 12 for a long period of time. The power requirements of an integrated circuit shift register are sufficiently small that the effective life of battery 14 is determined more from the shelf life thereof rather than the power drain. The key 10 is cooperative with an electronic lock 16 and is coupled thereto by three lines, labeled data out, data in and clock. The data out line carries data from memory 12 to the lock circuit, the data in line carries data from the lock circuit back into memory 12, and the clock line carries clock pulses for shifting of data in and out of memory 12. In actual implementation, a ground line would also interconnect key 10 and lock 16.
The lock circuit 16 includes a data gate 18 connected to a memory 20, and operative to couple data from memory 12 to memory 20, and to recirculate data from memory 12 back into memory 12 for restorage of a key code therein. The memory 20 has an output thereof coupled to a comparator 22 which also receives data from a master code generator 24. The output of comparator 22 is connected to logic circuitry 26 which provides a first output signal for actuation of associated utilization means, and a second output signal for providing an alarm indication in the event that an improper key code is employed.
Memory 20 and associated components of the lock 16 can also be typically implemented by integrated circuits. Timing of data from the key to the lock circuit is accomplished by means of a clock 28 providing clock signals to memory 12 and to a control circuit 30 which governs operation of memory 20 and also provides master timing signals to the lock system. An insertion detector 32 is provided in the lock for sensing the presence of key 10 therein and for providing in response to key detection a start signal to clock 28 for initiation of the key identification process. As will be described, the insertion detector 32 can also cause mechanical clamping of the key within the lock to prevent its premature withdrawal during the code recognition cycle and also to capture the key in the event that an improper key code is detected.
In operation, a multiple bit data word specifying a key code is stored in memory 12 representative of a unique key identity, this code being identical to a master code provided by generator 24 located in the lock circuitry. The key code contained within memory 12 is compared with the master code, positive identity between the two codes enabling actuation of the lock. Non-correspondence between one or more bits of the key code and the master code causes actuation of an alarm indicating an attempt to utilize an improper key. Upon insertion of key 10 into lock 16, the presence of the key as determined by insertion detector 32 causes enabling of clock 28. Clock pulses from clock 28 are applied to memory 12 and cause readout of the data stored therein to data gate 18 and thence to memory 20.
The data being shifted out of memory 12 is also recirculated via data gate 18 back into memory 12 to reload the key code for subsequent use. Upon loading of the data word into shift register 20, comparator 22 is operative to compare the data contents of register 20 with that of master code generator 24 and to provide output signals to logic 26 indicative of whether or not the coded data from key 10 is identical to the master code pattern. Comparison of the key code with the master code can be accomplished on a bit by bit basis or on the entire code word after it is shifted into comparator 22. If upon comparison between the master code and the key code there is identical correspondence of all bits therebetween, logic 26 provides an output signal to actuate the associated lock or other utilization means. It will be appreciated that the lock 16 can be associated with any utilization means which is to be key operated, such as a locking mechanism for a door, vault or the like, or electrical apparatus. If there is a lack of correspondence between one or more bits of the master code and the key code, logic 26 provides an alarm signal indicative of an erroneous key code. The alarm signal can immediately actuate an alarm indicator or can be employed with suitable counting circuitry to permit a selected number of decoding attempts before an alarm is actuated. Delayed alarm actuation is useful, for example, to prevent a transient condition such as momentary contact loss from causing an alarm.
The security of the present system is considerably enhanced by the feature wherein any attempt to employ an incorrect key code will serve to actuate an alarm. There is thus no opportunity to try different possible key codes in an attempt to actuate the lock, as the first wrong code will cause an alarm indication. It is possible to cause readout of data stored in memory 12 to ascertain its data content and thereby reproduce the key code. However, a key code can be employed as part of the data in memory 12 such that interrogation thereof will not reveal the key code. For example, data stored in memory 12 can be configured such that the code itself is contained at predetermined bit positions within a longer stored word and coding schemes can be selected which are extremely difficult if not practically impossible to decode. The length of the data word stored in memory 12 also serves to enhance security of the system; for example a 32 bit memory permits 2 32 possible coding combinations.
System security can be further enhanced by use of a key which communicates data to the lock circuit only upon receipt by the key of a proper interrogation code. Such a technique is illustrated in FIG. 2 which shows a first memory 34 coupled to a comparator 36 which, in turn, is coupled to a second memory 38. Each of the memories 34 and 38 are typically integrated circuit shift registers as described above. The memory 34 contains a predetermined code word which is compared in comparator 36 with an enable code which can be provided by the lock circuit. Upon detection by comparator 36 of identity between the enable code and the code stored in memory 34, a read command is provided to memory 38 to cause readout of a different code stored in memory 38. The code word from memory 38 is operative to actuate the lock after identity is established between this code and the master code stored in the lock circuit, as described above.
Upon interrogation of the key by an enable code which does not compare with the preprogrammed data in memory 34, comparator 36 can provide an alarm signal to the associated lock circuit. An alarm indication can also be provided as above upon non-identity between the master code in the lock and the code from memory 38. The technique of FIG. 2 thus affords a dual encoding arrangement which is of a higher order of security than the coding arrangement of FIG. 1. Additional levels of coding can also be readily provided according to the principles of this invention since small, low power digital circuitry can achieve the key function.
In addition to storage in the key of a key identification code for gaining access to the associated lock, the key can also contain additional data representing the identity of the particular key, an account number or the like. The system disclosed in FIG. 1 can be modified as indicated in FIG. 3 to accommodate such additional identification data. Referring to FIG. 3, data from a key is composed of a first word representing the key code and a second word representing other data such as a key number. This data is applied from the key to a pair of memory stages. The key code word is stored in memory 20a while the other identification code is stored in 20b. The key code is compared with the master code in comparator 22 in the same manner as described hereinabove.
The output of the comparator is applied to one input of an AND gate 23. The output of memory 20b is applied to a decoder 25, the output of which is applied to the second input of AND gate 23. The code processing cycle is governed by a counter 21 operative in response to clock signals from clock 28, the counter providing a timing sequence sufficient for loading data from the key into memories 20a and 20b. Upon identification of the key code in comparator 22, an output signal is provided by AND gate 23 for actuation of the lock. Failure to detect a proper key code will prevent a lock actuation output. In the embodiment of FIG. 3 failure to detect a proper code in memory 20b will also prevent lock actuation. It is evident that an output signal from decoder 25 representative of the additional identity code stored in the key can be employed to record such key identity, for example to denote the time that a particular key was employed with the associated lock.
A more particular embodiment of the invention is illustrated in FIG. 4. The key includes and has disposed therein a shift register 40 typically of the monolithic integrated circuit type and capable of storing a predetermined number of data bits which comprise a key code. Register 40 is powered by a suitable battery 42 which is also of small physical size to fit within a key element. Data from shift register 40 is communicative with the lock circuit by way of a data gate 44 operative to recirculate data back into shift register 40 to retain the same key code, or to load register 40 with new data to provide a new key code, as will be described.
Data from register 40 is applied to a digital comparator 46 which also receives information from a master code register 48. Register 48 contains a master code word as provided by a master code selector 50, which is used for comparison with the key code contained in the shift register 40. System timing is governed by a clock 52 which is started upon receipt of a start signal from a key insertion detector 32, such as described above. Detector 32 also energizes key clamp 33 which captures the key in the lock during the identification cycle. A clock provides two output signals, labeled respectively φ 1 and φ 2 , which are clock pulses recurring at the same clock rate but shifted in phase one from the other by a predetermined amount, typically 180°. The clock pulses φ 1 are advanced in phase from the clock pulses φ 2 and are employed to control data bit transitions, while the delayed clock pulses φ 2 are employed to control bit comparisons. Thus it will be appreciated that bit comparisons are accomplished at the midpoint of a bit interval to assure that such comparisons are performed after transients which may occur during bit transitions.
The clock pulses φ 1 are applied to register 48 and also to a counter 54 operative to count the number of bits shifted out of register 48. By means of a counter decoder 56, the last bit shifted out of register 48 is recognized to denote the end of the code comparison process. The key insertion detector 32 is operative to clamp the key in the lock to prevent its premature removal prior to completion of the decoding process. Detector 32 also provides a signal to flip-flop 58 to set the flip-flop to one logical state, the output signal thereof being applied to one input of an AND gate 62. Data in key register 40 and master register 48 are clocked out bit by bit by clock pulses φ 1 and are compared bit by bit in comparator 46. The comparator is operative to provide a first output, say zero, if the bit from the key register is identical to the bit from the master register, and to provide a second output, say one, if there is not correspondence between the received data bits. The output of comparator 46 is coupled to an AND gate 60 which also receives the clock pulses φ 2 , the output of gate 60 being applied to the reset input of flip-flop 58. The output of flip-flop 58 is coupled to one input of an AND gate 62, the other input of which is the output signal from counter decoder 56 for enabling gate 62.
Upon correspondence between a data bit from key register 40 and a date bit from master register 48, AND gate 60 will remain disabled and no reset signal will be applied to flip-flop 58. Thus, flip-flop 58 remains in its set state so long as there is identity between the key code and the master code providing an output signal to gate 62. Upon detection of the last bit of the master code by decoder 56, an output signal is provided therefrom to AND gate 62 to enable the gate and cause a signal for lock actuation. The signal from decoder 56 is also employed to release key clamp 33 to permit removal of the key from the lock. The output signal from gate 62 is the system output signal for activating the associated lock or other utilization means upon detection of a proper key code.
If, during comparison of any bit of the key code, a lack of identity is found between this bit and the associated bit of the master code in register 48, the output signal from comparator 46 will cause enabling of AND gate 60 and consequent resetting of flip-flop 58 which causes removal of the flip-flop output signal to gate 62. No actuation signal can be provided by reason of the disabling of gate 62. An output signal from gate 60 is provided only upon detection of an error between a bit of the key code and a corresponding bit of the master code, and this output signal is also employed to activate an alarm circuit 64 to indicate detection of an erroneous key code. Upon sensing of an alarm condition, a stop signal can be generated by alarm circuitry 64 to stop clock 52 and discontinue the decoding process and to prevent release of the key clamped in the lock by clamp 33.
In one mode of operation, the master code stored in register 48 is recirculated back into this register so that the code is available for subsequent data comparison. Similarly, the code in shift register 40 is recirculated therein by means of data gate 44 so that the same key code can later be employed. To further enhance the security of the novel lock system, however, the invention is also operative in another mode wherein the code residing in shift register 40 and master code register 48 is replaced with a new code. Such new code can be replaced on a regular basis or from time to time depending on particular security requirements.
To employ such a new code, the output signal of gate 62 provided upon identity between the key code and the master code, is applied via a switch 63 to set a flip-flop 66, one output of which is employed to energize a timing circuit 67 which, in turn, provides a start signal to clock 52. The other output of flip-flop 66 is applied to an AND gate 68 which also receives clock signals φ 1 . The output of gate 68 is applied to the clock input of a new code register 70 which has stored therein a new data code provided by a new code selector 72. The output of new code register 70 is applied to data gate 44 for coupling of such new data into key shift register 40. The new data is also applied to the master code register 48 for use in a subsequent data comparison. In this latter mode of operation, clock 52 is enabled for only a sufficient period of time determined by timing circuit 67 to permit shifting in the new code data into the key shift register 40 and to prevent reinstitution of the digital comparison process until the key is again inserted into the lock at a subsequent time.
The new code selector 72 can be implemented in several different ways and can include a binary word generator which is manually actuable such as by an array of switches, or automatically actuable for example by means of a computer. By use of a digital computer a new key code can be provided from a random number sequence generated by the computer such that the code is readily identifiable only in computer memory and need not be known to operating personnel in order to alter the key code. The master code can be updated immediately after completion of a particular decoding process or, alternatively, can be updated on a periodic basis. For example, in some circumstances it is desirable to reprogram the key code immediately after use of the key and to reprogram the master code on a daily basis to permit use of the key only once per day.
The key can be implemented in a variety of mechanical configurations to suit particular operating requirements. The key can, for example, be in a form much like an ordinary mechanical key as illustrated in FIG. 5. In this instance the key 80 is formed of a nonconductive material such as an epoxy and has the storage register 82 encapsulated therein. The battery in the form of a small button cell is contained within a battery compartment located in the handle portion of key 80, access thereto being provided by a removable cover 84. Electrical connection is provided at the distal end of key 80 by means of four conductive bands 86 provided on the end thereof each being of generally U-shaped configuration as illustrated.
The key is inserted within a keyway 88 of an associated lock, the contact bands 86 being cooperative with an electrical connector 87 disposed at the inner end of the keyway to provide connection between the key and the lock circuitry. Also disposed at the inner end of the keyway is a microswitch 90 which includes an actuation arm 92 disposed for actuation by the end of key 80 upon its insertion into the lock. The switch 90 is part of insertion detector 32 (FIG. 1) and is operative to provide a key insertion signal to the system clock for commencement of the key decoding process. A notch 94 is provided in one side of key 80 and is cooperative with a rod 94 associated with solenoid 96 to prevent removal of the key during the decoding process. The solenoid 96 is typically energized by a signal from key insertion detector 32.
As described hereinabove, an alarm signal is provided by the invention in the event that there is lack of comparison between the key code and the master code of the lock. Premature withdrawal of the key could also cause an alarm condition and to prevent such an occurrence, the key is clamped within the lock by solenoid 96 until completion of the decoding cycle. The key can also be retained in the lock in the event that an erroneous code is detected to prevent its removal in such event. The key code can be arranged such that the first bit to be read out of the key is always of ground potential such that ground potential exists on all terminal contacts 86 when the key is not in use, to thereby prevent accidental shorting of the key which could destroy the stored data. The key terminals could alternatively be deactivated when the key is not in use by a suitable switch arrangement.
From the foregoing it will be evident that an electronic lock system has been provided which is both reliable and highly secure and which can be constructed in an efficient and commerically realistic manner. Various modifications and alternative implementations will occur to those versed in the art without departing from the spirit and true scope of the invention. For example, data can be conveyed from the key memory to the lock in a parallel rather than a serial manner, and various levels of coding can be provided to suit the desired level of security. The electronic circuitry and its mechanical housing can take a wide variety of forms adapted to specific installation requirements. Accordingly, it is not intended to limit the invention by what has been particularly shown and described, except as indicated in the appended claims.
This invention relates to lock systems and more particularly to an electronic lock system employing active digital electronic circuitry in both the key and lock.
BACKGROUND OF THE INVENTION
Electronic locks have been proposed in which an electronic circuit in a lock is energized to activate the lock by use of a key containing circuitry cooperative with the lock circuit. The circuitry employed in a key has generally been of a type in which a plurality of coded interconnections are provided to appropriately energize an associated lock circuit. Such key circuitry, however, usually contains a fixed code which is alterable only by rewiring of the key circuit. There is little versatility of coding in such conventional systems. In addition, the configuration of the key circuit can be ascertained by appropriate analysis and the code thereby duplicated. As a further disadvantage, such keys usually require a relatively large number of interconnections with the lock, with attendant increase in system cost and complexity.
SUMMARY OF THE INVENTION
In accordance with the present invention, a highly reliable and secure electronic lock system is provided in which active data storage means are provided within a key containing a readily alterable coded data word corresponding to a master code stored in an associated lock circuit. Upon insertion of the key into the lock, the data stored in the key is compared with a master code in the lock, identity therebetween causing actuation of the lock. In the event that there is not exact comparison between the master code and the key code, an alarm can be actuated and the key seized within the lock to prevent its removal therefrom. By immediate actuation of an alarm in the event of detection of one or more incorrect bits of the key code, there is little opportunity to attempt duplication of the key code and thereby materially enhancing the security of the system. Analysis of the data storage circuitry within the key will not reveal the data code stored therein and even if the stored data were read out by interrogation of the key, the data can be selectively coded such that it would be, in practice, substantially impossible to analyze and decode the data content thereof.
In a typical embodiment of the invention, the key contains a multiple bit shift register for storing the key code and is typically of the integrated circuit type having extremely low energy requirements. Power is provided by a small battery source located within the key. Alternatively, the shift register can be of the nonvolatile type requiring no external power, in which case no battery need be employed. Only four connections are required between the key and the associated lock; one for transferring data from the key to the lock, one for transferring data from the lock back into the key, a ground connection and a clock line. Such connection can be made by various electrical contact elements suited to particular system requirements or, as an alternative, connection can be made inductively.
DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a simplified block diagram representation of a lock system according to the invention;
FIG. 2 is a block diagram of an alternative key circuit embodying the invention;
FIG. 3 is a partial block diagram of an alternative lock circuit embodying the invention;
FIG. 4 is a more detailed block diagram of a lock system according to the invention; and
FIG. 5 is a pictorial view, partly in section, illustrating a typical key configuration embodying the invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1 there is shown an electronic key 10 having a memory 12 powered by a suitable energy source such as a battery 14. The memory is typically a shift register of the low power type constructed by monolithic integrated circuit techniques and is, therefore, of extremely small physical configuration capable of being readily mounted in a small key member. The battery is typically a low power mercury battery also adapted for mounting in the key member and capable of energizing memory 12 for a long period of time. The power requirements of an integrated circuit shift register are sufficiently small that the effective life of battery 14 is determined more from the shelf life thereof rather than the power drain. The key 10 is cooperative with an electronic lock 16 and is coupled thereto by three lines, labeled data out, data in and clock. The data out line carries data from memory 12 to the lock circuit, the data in line carries data from the lock circuit back into memory 12, and the clock line carries clock pulses for shifting of data in and out of memory 12. In actual implementation, a ground line would also interconnect key 10 and lock 16.
The lock circuit 16 includes a data gate 18 connected to a memory 20, and operative to couple data from memory 12 to memory 20, and to recirculate data from memory 12 back into memory 12 for restorage of a key code therein. The memory 20 has an output thereof coupled to a comparator 22 which also receives data from a master code generator 24. The output of comparator 22 is connected to logic circuitry 26 which provides a first output signal for actuation of associated utilization means, and a second output signal for providing an alarm indication in the event that an improper key code is employed.
Memory 20 and associated components of the lock 16 can also be typically implemented by integrated circuits. Timing of data from the key to the lock circuit is accomplished by means of a clock 28 providing clock signals to memory 12 and to a control circuit 30 which governs operation of memory 20 and also provides master timing signals to the lock system. An insertion detector 32 is provided in the lock for sensing the presence of key 10 therein and for providing in response to key detection a start signal to clock 28 for initiation of the key identification process. As will be described, the insertion detector 32 can also cause mechanical clamping of the key within the lock to prevent its premature withdrawal during the code recognition cycle and also to capture the key in the event that an improper key code is detected.
In operation, a multiple bit data word specifying a key code is stored in memory 12 representative of a unique key identity, this code being identical to a master code provided by generator 24 located in the lock circuitry. The key code contained within memory 12 is compared with the master code, positive identity between the two codes enabling actuation of the lock. Non-correspondence between one or more bits of the key code and the master code causes actuation of an alarm indicating an attempt to utilize an improper key. Upon insertion of key 10 into lock 16, the presence of the key as determined by insertion detector 32 causes enabling of clock 28. Clock pulses from clock 28 are applied to memory 12 and cause readout of the data stored therein to data gate 18 and thence to memory 20.
The data being shifted out of memory 12 is also recirculated via data gate 18 back into memory 12 to reload the key code for subsequent use. Upon loading of the data word into shift register 20, comparator 22 is operative to compare the data contents of register 20 with that of master code generator 24 and to provide output signals to logic 26 indicative of whether or not the coded data from key 10 is identical to the master code pattern. Comparison of the key code with the master code can be accomplished on a bit by bit basis or on the entire code word after it is shifted into comparator 22. If upon comparison between the master code and the key code there is identical correspondence of all bits therebetween, logic 26 provides an output signal to actuate the associated lock or other utilization means. It will be appreciated that the lock 16 can be associated with any utilization means which is to be key operated, such as a locking mechanism for a door, vault or the like, or electrical apparatus. If there is a lack of correspondence between one or more bits of the master code and the key code, logic 26 provides an alarm signal indicative of an erroneous key code. The alarm signal can immediately actuate an alarm indicator or can be employed with suitable counting circuitry to permit a selected number of decoding attempts before an alarm is actuated. Delayed alarm actuation is useful, for example, to prevent a transient condition such as momentary contact loss from causing an alarm.
The security of the present system is considerably enhanced by the feature wherein any attempt to employ an incorrect key code will serve to actuate an alarm. There is thus no opportunity to try different possible key codes in an attempt to actuate the lock, as the first wrong code will cause an alarm indication. It is possible to cause readout of data stored in memory 12 to ascertain its data content and thereby reproduce the key code. However, a key code can be employed as part of the data in memory 12 such that interrogation thereof will not reveal the key code. For example, data stored in memory 12 can be configured such that the code itself is contained at predetermined bit positions within a longer stored word and coding schemes can be selected which are extremely difficult if not practically impossible to decode. The length of the data word stored in memory 12 also serves to enhance security of the system; for example a 32 bit memory permits 2 32 possible coding combinations.
System security can be further enhanced by use of a key which communicates data to the lock circuit only upon receipt by the key of a proper interrogation code. Such a technique is illustrated in FIG. 2 which shows a first memory 34 coupled to a comparator 36 which, in turn, is coupled to a second memory 38. Each of the memories 34 and 38 are typically integrated circuit shift registers as described above. The memory 34 contains a predetermined code word which is compared in comparator 36 with an enable code which can be provided by the lock circuit. Upon detection by comparator 36 of identity between the enable code and the code stored in memory 34, a read command is provided to memory 38 to cause readout of a different code stored in memory 38. The code word from memory 38 is operative to actuate the lock after identity is established between this code and the master code stored in the lock circuit, as described above.
Upon interrogation of the key by an enable code which does not compare with the preprogrammed data in memory 34, comparator 36 can provide an alarm signal to the associated lock circuit. An alarm indication can also be provided as above upon non-identity between the master code in the lock and the code from memory 38. The technique of FIG. 2 thus affords a dual encoding arrangement which is of a higher order of security than the coding arrangement of FIG. 1. Additional levels of coding can also be readily provided according to the principles of this invention since small, low power digital circuitry can achieve the key function.
In addition to storage in the key of a key identification code for gaining access to the associated lock, the key can also contain additional data representing the identity of the particular key, an account number or the like. The system disclosed in FIG. 1 can be modified as indicated in FIG. 3 to accommodate such additional identification data. Referring to FIG. 3, data from a key is composed of a first word representing the key code and a second word representing other data such as a key number. This data is applied from the key to a pair of memory stages. The key code word is stored in memory 20a while the other identification code is stored in 20b. The key code is compared with the master code in comparator 22 in the same manner as described hereinabove.
The output of the comparator is applied to one input of an AND gate 23. The output of memory 20b is applied to a decoder 25, the output of which is applied to the second input of AND gate 23. The code processing cycle is governed by a counter 21 operative in response to clock signals from clock 28, the counter providing a timing sequence sufficient for loading data from the key into memories 20a and 20b. Upon identification of the key code in comparator 22, an output signal is provided by AND gate 23 for actuation of the lock. Failure to detect a proper key code will prevent a lock actuation output. In the embodiment of FIG. 3 failure to detect a proper code in memory 20b will also prevent lock actuation. It is evident that an output signal from decoder 25 representative of the additional identity code stored in the key can be employed to record such key identity, for example to denote the time that a particular key was employed with the associated lock.
A more particular embodiment of the invention is illustrated in FIG. 4. The key includes and has disposed therein a shift register 40 typically of the monolithic integrated circuit type and capable of storing a predetermined number of data bits which comprise a key code. Register 40 is powered by a suitable battery 42 which is also of small physical size to fit within a key element. Data from shift register 40 is communicative with the lock circuit by way of a data gate 44 operative to recirculate data back into shift register 40 to retain the same key code, or to load register 40 with new data to provide a new key code, as will be described.
Data from register 40 is applied to a digital comparator 46 which also receives information from a master code register 48. Register 48 contains a master code word as provided by a master code selector 50, which is used for comparison with the key code contained in the shift register 40. System timing is governed by a clock 52 which is started upon receipt of a start signal from a key insertion detector 32, such as described above. Detector 32 also energizes key clamp 33 which captures the key in the lock during the identification cycle. A clock provides two output signals, labeled respectively φ 1 and φ 2 , which are clock pulses recurring at the same clock rate but shifted in phase one from the other by a predetermined amount, typically 180°. The clock pulses φ 1 are advanced in phase from the clock pulses φ 2 and are employed to control data bit transitions, while the delayed clock pulses φ 2 are employed to control bit comparisons. Thus it will be appreciated that bit comparisons are accomplished at the midpoint of a bit interval to assure that such comparisons are performed after transients which may occur during bit transitions.
The clock pulses φ 1 are applied to register 48 and also to a counter 54 operative to count the number of bits shifted out of register 48. By means of a counter decoder 56, the last bit shifted out of register 48 is recognized to denote the end of the code comparison process. The key insertion detector 32 is operative to clamp the key in the lock to prevent its premature removal prior to completion of the decoding process. Detector 32 also provides a signal to flip-flop 58 to set the flip-flop to one logical state, the output signal thereof being applied to one input of an AND gate 62. Data in key register 40 and master register 48 are clocked out bit by bit by clock pulses φ 1 and are compared bit by bit in comparator 46. The comparator is operative to provide a first output, say zero, if the bit from the key register is identical to the bit from the master register, and to provide a second output, say one, if there is not correspondence between the received data bits. The output of comparator 46 is coupled to an AND gate 60 which also receives the clock pulses φ 2 , the output of gate 60 being applied to the reset input of flip-flop 58. The output of flip-flop 58 is coupled to one input of an AND gate 62, the other input of which is the output signal from counter decoder 56 for enabling gate 62.
Upon correspondence between a data bit from key register 40 and a date bit from master register 48, AND gate 60 will remain disabled and no reset signal will be applied to flip-flop 58. Thus, flip-flop 58 remains in its set state so long as there is identity between the key code and the master code providing an output signal to gate 62. Upon detection of the last bit of the master code by decoder 56, an output signal is provided therefrom to AND gate 62 to enable the gate and cause a signal for lock actuation. The signal from decoder 56 is also employed to release key clamp 33 to permit removal of the key from the lock. The output signal from gate 62 is the system output signal for activating the associated lock or other utilization means upon detection of a proper key code.
If, during comparison of any bit of the key code, a lack of identity is found between this bit and the associated bit of the master code in register 48, the output signal from comparator 46 will cause enabling of AND gate 60 and consequent resetting of flip-flop 58 which causes removal of the flip-flop output signal to gate 62. No actuation signal can be provided by reason of the disabling of gate 62. An output signal from gate 60 is provided only upon detection of an error between a bit of the key code and a corresponding bit of the master code, and this output signal is also employed to activate an alarm circuit 64 to indicate detection of an erroneous key code. Upon sensing of an alarm condition, a stop signal can be generated by alarm circuitry 64 to stop clock 52 and discontinue the decoding process and to prevent release of the key clamped in the lock by clamp 33.
In one mode of operation, the master code stored in register 48 is recirculated back into this register so that the code is available for subsequent data comparison. Similarly, the code in shift register 40 is recirculated therein by means of data gate 44 so that the same key code can later be employed. To further enhance the security of the novel lock system, however, the invention is also operative in another mode wherein the code residing in shift register 40 and master code register 48 is replaced with a new code. Such new code can be replaced on a regular basis or from time to time depending on particular security requirements.
To employ such a new code, the output signal of gate 62 provided upon identity between the key code and the master code, is applied via a switch 63 to set a flip-flop 66, one output of which is employed to energize a timing circuit 67 which, in turn, provides a start signal to clock 52. The other output of flip-flop 66 is applied to an AND gate 68 which also receives clock signals φ 1 . The output of gate 68 is applied to the clock input of a new code register 70 which has stored therein a new data code provided by a new code selector 72. The output of new code register 70 is applied to data gate 44 for coupling of such new data into key shift register 40. The new data is also applied to the master code register 48 for use in a subsequent data comparison. In this latter mode of operation, clock 52 is enabled for only a sufficient period of time determined by timing circuit 67 to permit shifting in the new code data into the key shift register 40 and to prevent reinstitution of the digital comparison process until the key is again inserted into the lock at a subsequent time.
The new code selector 72 can be implemented in several different ways and can include a binary word generator which is manually actuable such as by an array of switches, or automatically actuable for example by means of a computer. By use of a digital computer a new key code can be provided from a random number sequence generated by the computer such that the code is readily identifiable only in computer memory and need not be known to operating personnel in order to alter the key code. The master code can be updated immediately after completion of a particular decoding process or, alternatively, can be updated on a periodic basis. For example, in some circumstances it is desirable to reprogram the key code immediately after use of the key and to reprogram the master code on a daily basis to permit use of the key only once per day.
The key can be implemented in a variety of mechanical configurations to suit particular operating requirements. The key can, for example, be in a form much like an ordinary mechanical key as illustrated in FIG. 5. In this instance the key 80 is formed of a nonconductive material such as an epoxy and has the storage register 82 encapsulated therein. The battery in the form of a small button cell is contained within a battery compartment located in the handle portion of key 80, access thereto being provided by a removable cover 84. Electrical connection is provided at the distal end of key 80 by means of four conductive bands 86 provided on the end thereof each being of generally U-shaped configuration as illustrated.
The key is inserted within a keyway 88 of an associated lock, the contact bands 86 being cooperative with an electrical connector 87 disposed at the inner end of the keyway to provide connection between the key and the lock circuitry. Also disposed at the inner end of the keyway is a microswitch 90 which includes an actuation arm 92 disposed for actuation by the end of key 80 upon its insertion into the lock. The switch 90 is part of insertion detector 32 (FIG. 1) and is operative to provide a key insertion signal to the system clock for commencement of the key decoding process. A notch 94 is provided in one side of key 80 and is cooperative with a rod 94 associated with solenoid 96 to prevent removal of the key during the decoding process. The solenoid 96 is typically energized by a signal from key insertion detector 32.
As described hereinabove, an alarm signal is provided by the invention in the event that there is lack of comparison between the key code and the master code of the lock. Premature withdrawal of the key could also cause an alarm condition and to prevent such an occurrence, the key is clamped within the lock by solenoid 96 until completion of the decoding cycle. The key can also be retained in the lock in the event that an erroneous code is detected to prevent its removal in such event. The key code can be arranged such that the first bit to be read out of the key is always of ground potential such that ground potential exists on all terminal contacts 86 when the key is not in use, to thereby prevent accidental shorting of the key which could destroy the stored data. The key terminals could alternatively be deactivated when the key is not in use by a suitable switch arrangement.
From the foregoing it will be evident that an electronic lock system has been provided which is both reliable and highly secure and which can be constructed in an efficient and commerically realistic manner. Various modifications and alternative implementations will occur to those versed in the art without departing from the spirit and true scope of the invention. For example, data can be conveyed from the key memory to the lock in a parallel rather than a serial manner, and various levels of coding can be provided to suit the desired level of security. The electronic circuitry and its mechanical housing can take a wide variety of forms adapted to specific installation requirements. Accordingly, it is not intended to limit the invention by what has been particularly shown and described, except as indicated in the appended claims.