GB2265412A

GB2265412A - Electronic key and lock

Info

Publication number: GB2265412A
Application number: GB9207005A
Authority: GB
Inventors: Ian Francis Deviny
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-03-27
Filing date: 1992-03-27
Publication date: 1993-09-29
Also published as: GB9207005D0

Abstract

An electronic key and lock wherein a randomly generated binary digit sequence is generated by the lock, transmitted to the key, is received by the key and a changed binary digit sequence is generated by applying a unique and predetermined boolean function of the input digit sequence to produce each digit of the output. The changed output digit sequence is transmitted to the lock whereupon the lock determines from previously programmed instructions whether the key used is the same as previously authorised key.

Description

ELECTRONIC KEY AND LOCK This invetion relates to an electronic tey and lock.

Electronic devices that, operate electronic locks are known as an alternative to mechanical lock and kej systems. Their advantage being an increased umber of combinations, a non physical contact mode of operation, and resistance to riefeate of tne lock by nechanical means, Such derices use various types of transmission mediums such as ultrasonic sound infra red light, and radio waves, to transmit a coded signal from the key to the lock that if previously authorised and programmed to accept the coded signal will open +.he loc. < .

The degree of security of such a lock is related to the ease of detecting ard copying +ne transmitted signals from key to lock. Methods are known of changing the coded signal after eah use of the key however in some cases this prevents the use of mere than one key for each lock.

According to the present invention there is provided a:1 electronic lock and key wherein a randomly generated binary digit sequence transmitted by the lock anr received by the key, is changed by the key in a unique way specific to the particular key being used, and transmitted back to the lock, whereupon the lock determines wnether the changed binary digit sequence matches that which the lock has determined would be the case for a own and authorised send.

Also according to tis in-rention there is roved a method cf electronic circuitry for the key wnerein a unique combination of boolean function in the form cf MOR,NAND,XOR, or otner basic logic gate structure is programmed irto the key to operate on the received binary digit sequence and produce a changed, or scrambled, but unique binary digit sequence to be trarsTit+ed to the lock.

Also according to this irvention there is provided an electronic lock wherein the unique boolean function for a particular key is programmed into the lock so that after sending a randomly generated binary digit sequence and receiving the scrambled binary digit sequence back from the key, a central processing unit (CPU) can deterrrine whether the key being used is the same as for that which the boolean function therein programmed is tre same.

X specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which The drawings are in block function format wherein each blocs describes an electronic function that can be created using known methods of electronic design from the functional description herewith described.

Figure 1 shows in block functional diagram format, electronic circuitry to be encompassed in the electronic key wherein; The Signal Reception Device is the component that converts the received signal into an electronic series of pulses, for example a phototransistor, a radio receiver, or an ultrasonic transducer, and supplies these pulses to the Input Signal Decoding logic.

The Input Signal Decoding is the logic circuitry that interprets beginning and ending markers of the received signal, converts the signal into a sequence of binary digits, for example 32 digits, and serially clocks these digits into the Input Word Shift Register.

The Input Word Shift Register is filled with the binary digit sequence and when full, as indicated by the detection of an end of sequence signal from the Input Signal Decoding, enables the SCRAMBLE logic.

The Scramble logic performs the boolean function on the digit sequence in a way programmed during manufacture, or afterwards, and provides the resulting sequence for entry into the Output Word Shift Register.

The Output Signal Coding formats the digit sequence, adding start and ending control signals, into a form suitable for transmission through the Signal Transmission Device.

Te signal transmission device is the compliment to the reception device, for example light emitting diode.

The programming interface enables external input to the Scamble logic and Owner Identification Register during manufacture or afterwards.

The Owner Identification Register contains logic to be programmed in binary format with unique information, for example the key owners name, to be used as a reference name for the key by the lock.

Figure 2 snows in block functional diagrari. format, electronic circuitry to be encompassed in the electronic lock wherein: The Signal Reception Device converts a received signal from.

the Key into an electronic series of pulses and supplies these pulses to the Input ignal Decoding logic.

The Input Signal Decoding Logic interprets the received signal and either, in the case of receiving an initiate lock sequence, detects an iniate sequence command and enables the CPU (Embedded Controller) t.o begin it's programmed function, or in the case of receiving the scrambled binary digit sequence from the Key, interprets beginning and end markers of the received signal, converts the signal into a sequence of binary digits and serially clocks these digits into the Input Word Shift Register Thh Input Word Shift register is filled with the binary digit sequence and when full lags the CPU.

The CPU, on detection of an initiate sequence, sends a command signal 0 the Output Signal Coding which when received by the key iniates the key to send the contents of it's Owner Identification register. On receipt of the contents of the Owner Identification register, via the Input Word Shift Register, the CPU uses a lockup table to identify if the key being used has been previously programmed to open the lock. If this is not the case then no further functions are performed. If the contents of the Owner Identification register are found to be from a valid key, the CPU then generates a random binary digit sequence, of for example 32 digits, for transmission via the Output Word register to the key. On receipt of the scrambled sequence from the key a fixed time later, the CPU performs the programmed boolean function on the original binary digit sequence and compares it with the received scrambled sequence, and if the same sends a signal to the Unlock Activation circuitry.

The Unlock Activation circuitry enables a servo mechanism via a relay or power transistor which opens the lock.

The Output Word shift register receives binary digit sequences to be output serially to the Output Signal Coding.

The C'utput Signal Coding formats the digit sequence, adding start and end control signals, into a form suitable for transtnission and outputs the signal to the signal Transmission Device.

Phe Sicnal Transmission Device is the complement transmission device to the examples given for the signal receiving device.

The Progamming interface enables external input to program the CPU during manufacture, or afterwards, to program the lock to accept a given key defined by a unique boolean function, or to remove key functions already programmed.

Figure 3 shows an arrangement of logic gates (1) and programmable connections (2 that can be programmed to produce one of a large number of different boolean functions cn an inputted binary digit sequence to ize used in the Scramble logic section of figure 1.

The section shown , to produce the first binary digit output, is indicated as being repeated for each digit up to the length of the incoming binary digit sequence, for example for 32 digits the value of n would be equal to 32. lach repeated section is programmed randomly and uniquely during manufacture or afterwards to produce a boolean function for each output digit which is a function of the whole input binary digit sequence.

An example of the boolean function for the nth output digit would be: On = (I1+I7.I30.I25+l9+I27)+(I11.I19.I25.I8) where "." refers to logical AND, "+" refers to logical OR, and "I" refers to logical inverse of I.

Referring to the drawing of figure 1, the electronic key comprises Seauence Initiation logic which on detection of a key operating event, for example operation of a push button swithh, causes the Output Signal coaxing to issue a signal via the Signal Transmission device, for example an LED (light emitting diode), which any lock within reception distance of the signal will detect and interpret as a command to send a signal back to the key which the key will interpret as a command to be,in sending unique data stored in the Owner Identification register via the Output Signal coding and LED to be received by the lock.

The lock 1 recieve this data and use. it to identify which set cf programming instructions, pèviousl;9 stored, will be used when the lock comes to the stage of identif/ing whether the key is authorised to open the lock.

After receiving the contents of the Owner Identification register, the CPU as shown in figure 2 will generate a random series of binary digits which will be sent to the key.

The key will recieve te series of binary digits and pass them into the Input Word Shift register as shown in figure 1. When the final binary digit is received by the key the The Input Signal Decoding will enable the received word to be input to the Scramble logic. Each digit output of the Scramble logic becomes a boolean function of the input word shift register and the output digit sequence is then transmitted via the output signal coding and LWD to the lock.

On receipt of the returned digit sequence, the loge of the CPU compares this sequence with the result obtained from performing the previously determined programming instructions on the original word sent out to the key and If they are the same then the unlock activation is enabled, and if not the same the unlock activation logic remains disabled.

Claims

1 An electronic key and 1sok wherein a randomly generated binary digit sequence transmitted by the lock and received by the key, is changed by the key in a unique way specific to the particular key being used, and transmitted back to the lock whereupon the lock determines whether the changed binary digit sequence matches that which the lock has determined would he the case for a known and authorised key.

2 An electronic key as claimed in claim 1, wherein the method of changing the binary digit sequence is performed by an arrangement of logic gates that can configured during manufacture, or afterwards, in many different ways to provide many different combinations of ways of changing a binary digit sequence and therefore many different key.

combinations by performing a boolean function on the binary digit sequence.

3 An electronic look as claimed in claim 1 wherein a; set ot program instructions is provided that allow the lock to determine if-the chånged sequence of binary digits received from the key in response to a random binary digit sequence sent by the lock as claimed in claim 1 or claim 2 is the same as would be received from a key with the correct and previously allowed combination.

4 An electronic key and lock as claimed in claims -1.2 and 3 wherein; many different keys can be authorised or programmed ito allow opening of the lock by using as many different sets of programming instruction within the electronic lock.