Patent Publication Number: US-8536979-B2

Title: Authentication apparatus and authentication method using random pulse generator

Description:
TECHNICAL FIELD 
     The present invention relates to an authentication apparatus and an authentication method using a completely random signal as an authentication signal from a random pulse generator to generate completely random pulses. 
     BACKGROUND ART 
     In the conventional authentication apparatus such as an electronic lock, a key manufacturer determines an authentication data in advance, and completes and sells, as a set, a key body (or a lock) and a key to be inserted into the key body. The user purchases the complete product and uses by mounting it on the front door, for example, at a required point. In electronic locks of other types, the time when the lock has been shut is stored in the key body and the key as authentication data, which is collated at the time of opening the lock (Japanese Patent Application Laid-open No. H07-233663), or a voiceprint (or a voice pattern) is used as authentication data (for example, Japanese Patent Application Laid-open No. H08-257216). 
     DISCLOSURE OF THE INVENTION 
     The conventional authentication apparatuses are discussed below with reference to the electronic lock as a specific application. In the conventional electronic locks fabricated with authentication data predetermined by the manufacturer, the authentication data are fixed and cannot be freely changed (actually, the manufacturer creates the authentication data according to a program, and the number of sets thereof is limited, so that the same authentication data is liable to be used undesirably), or even if changeable, the authentication data is input by ten-keys or the like and therefore the number of digits and the number of sets available are limited. 
     In many cases, the manufacturer is required to hold the authentication data of the products for maintenance and services necessitates a vast amount to secure confidentiality. When the key sets are limited, for example, the chance of the same authentication data being used increases. The manufacturer, therefore, is required to manage the keys by taking care not to distribute the same key sets in the same area. Further, the prevention of data leakage unavoidably depends on the quality of the manager, and therefore the preventive measures cannot be complete and limited. 
     Incidentally, when a plurality of the same authentication data are used, the use of an electronic lock, for example, in an automotive vehicle may also inconveniently open the door of another vehicle which may be parked in the same parking lot. 
     Assume, on the other hand, that the locked time is used as authentication data. In view of the fact that time is data changing regularly with time, however, the locked time is not proper as authentication data requiring irregularities. The data may be easily decoded from the number of digits thereof, or a copy key can be easily fabricated by simultaneous use, thereby inconveniently posing the security problem. 
     The authentication data using the voiceprint, on the other hand, requires a complicated device to identify the voiceprint and therefore is not suitable as a generally applicable electronic lock. 
     Both time and the voiceprint depend on the external environments (namely an authentication signal completely free of environmental factors cannot be generated in the key or the key body). The key system, therefore, can be unlocked by the artificial operation of a person having full knowledge of the mechanism thereof, and has a limit in security. 
     This invention has been achieved to obviate the problems of the conventional authentication apparatuses, or especially the electronic lock described above, and an object thereof is to provide an authentication apparatus comprising a body, a partner side paired with the body, in which there are compared with a random pulse generator (hereinafter referred to as the RPG), arranged in the body or the partner side or in both the body and the partner side, which generates random pulses, a means which outputs authentication data based on the random pulses generated by the RPG, a means which stores authentication data, a communication means which transmits/receives authentication data, and a control means which controls the communication of authentication data and collates authentication data. 
     Another object of the invention is to provide an authentication method comprising the steps of: generating random pulses by a random pulse generator (hereinafter referred to as the RPG) arranged in a body or a partner side paired with the body or in both in the body and the partner side; outputting authentication data based on the random pulses generated by the RPG; storing authentication data; transmitting/receiving authentication data; and controlling the communication of authentication data and collating authentication data. 
     In the authentication apparatus and the authentication method according to this invention, a RPG utilizing the a particles infinitely released by the natural collapse, for example, is incorporated in the key body, and an original, random signal completely free of the effects of the environmental conditions and never controllable artificially is obtained from the RPG. This signal is used as an authentication signal of a key. Therefore, the authentication signal can be generated any time in the key, and a new, completely random data can be written each time of use. It is impossible to copy it, and therefore the data management by the key manufacturer is eliminated. In this way, the security of the user is fully maintained and safety established. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a diagram for explaining a key authentication apparatus using a random pulse generator (RPG) according to an embodiment of the invention. 
         FIG. 1B  is a diagram for explaining the manner in which the authentication apparatus shown in  FIG. 1A  is used. 
         FIG. 2  is a block diagram showing a random pulse generator used in an embodiment of the invention. 
         FIG. 3  is a front view showing a diode with an α radiator used with the random pulse generator according to the invention. 
         FIG. 4  is a perspective view of a zener diode used with the random pulse generator according to the invention. 
         FIG. 5  is a graph showing an example of an output waveform of the random pulse generator according to the invention. 
         FIG. 6  is a block diagram showing an example of the circuit of the key body according to the invention. 
         FIG. 7  is a block diagram showing an example of the circuit of the key according to the invention. 
         FIG. 8  is a flowchart showing the communication procedures between a key body and a key paired with the key body according to the invention. 
         FIG. 9  is a diagram for explaining a method of displaying by classification of the output pulses of the random pulse generator according to the invention. 
         FIG. 10  is a block diagram showing an example of the configuration of a RPG module according to the invention. 
         FIG. 11  is a diagram for explaining the configuration of the random pulse generator using RF. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     An authentication apparatus and method using a random pulse generator (RPG) according to the invention are explained in detail below with reference to an electronic lock as an embodiment. 
       FIG. 1A  is a diagram for briefly explaining an electronic lock according to this invention, and  FIG. 1B  is a diagram for explaining the manner in which the electronic lock shown in  FIG. 1A  is used. In the drawings, the reference numeral  1  denotes a door knob, the reference numeral  2  denotes a fingerprint authentication apparatus, the reference numeral  3  denotes a ten-key unit, the reference numeral  10  denotes an electronic lock body, the reference numeral  11  denotes a random pulse generator (hereinafter referred to as the RPG) built in the electronic lock body, the reference numeral  12  denotes a memory built in the electronic lock body, the reference numeral  20  denotes a key, and the reference numeral  21  denotes a memory built in the key. 
     The RPG used for generating completely random pulses is constituted of an a particle detector described in, for example, Japanese Patent No. 2926539 granted to the present inventor. The α particle radiator used in this case is  241 Am,  244 Cm,  210 Pb- 210 Po,  210 Po, or the like which naturally collapses. In the case of the electronic lock used for the part having a shield space such as a safety box, the RPG for generating random pulses using the beta ray or the gamma ray may be used. 
     The α particles, the beta ray and the gamma ray are not affected by the environmental factors such as temperature, pressure, humidity or electromagnetic wave, and therefore cannot be controlled artificially. This property is an important factor to secure safety which cannot be realized by other methods. For the electronic lock used for the part not requiring a complete safety, on the other hand, thermal electrons or semiconductor jitters may be used as a source of random pulses. 
     The key body has built therein a RPG, an electronic circuit for making it possible to use the random pulses sent out from the RPG as an authentication signal, a circuit (storage element) for storing the authentication signal, a circuit for transmitting and receiving the authentication signal in accordance with the communication mode and, if necessary, an antenna, a communication device, a power supply, etc. Incidentally, power may alternatively be supplied from an external source by communication (electromagnetic induction, radio wave or terminal connection). 
     First, a random pulse generator (RPG)  11  for generating random pulses voluntarily is explained. 
     The RPG, as shown in  FIG. 2 , includes a pulse generating unit  11 A, a pre-amplifier  11 B, a main amplifier  11 C and a waveform shaping unit  11 D. 
     The pulse generating unit  11 A is, configured of a device selected in accordance with the safety required of the key (electronic lock). For the key requiring the highest safety, a device (diode with the α particle radiator) having an α particle radiator shown in  FIG. 3  is used. In the drawing, the reference numeral  11   b  denotes a can seal. The α particles (He atoms) are released from the α radiator semipermanently and voluntarily in accordance with the half life period thereof without any power supply in a manner completely free of the effects of the environmental factors such as temperature, pressure or electromagnetic wave. Specifically, this method has the feature that the original signal used for authentication is produced from a signal source totally incapable of human control. This signal source, therefore, can never be changed from outside. Incidentally, the use of a radioactive capsule is disclosed in Japanese Patent No. 2926539 described above. 
     When the key mounting portion does not always require complete safety, the pulse generating unit may be configured of a diode (zener diode) as shown in  FIG. 4 . 
     In the pre-amplifier  11 B, a minute pulse signal generated by the pulse generating unit  11 A is amplified as an input signal of the main amplifier  11 C. 
     The main amplifier  11 C amplifies a signal to discriminate the signal clearly from noises. In this circuit, the voltage of 0.5 or lower containing noises is processed separately as a band containing a noise signal. The voltage processed as a discrete level is set in accordance with the signal strength and noise level required ( FIG. 5 ). 
     In the waveform shaping unit  11 D, a pulse width is added to the pulse output as a leading waveform from the main amplifier  11 C so that it can be handled as an authentication signal. The pulse waveform output from the RPG is shown in  FIG. 5 . 
     Incidentally, the random pulse of the RPG has a height (or crest) value and pulse interval which are both random, as shown in  FIG. 9 . Therefore, the voltage of the height value can be converted into a digital random value, and since the number of clock pulses to measure the pulse interval can also be used as a random value. Also, as shown in the same drawing, a combination of voltage and number of clock pulses may be used. For example, a pulse  1  is given as (9, 5), a pulse  2  is given as (4, 3), a pulse  3  is given as (7, 6) and a pulse  4  is given as (10, 3). 
     The circuit of the key body is shown in  FIG. 6 . The key body  10  is configured of a power supply module  13 , an insertion detection module  14 , a transceiver module  15  and a RPG module  16 . 
     The power supply module  13  supplies an operation power to the constituent circuits as a whole, and according to the embodiment shown in the drawing, includes a DC-DC converter U 1  for supplying a stabilized voltage of 5 V. 
     The insertion detection module  14  detects the insertion of the key constituting the partner side by, for example, the contact between the key body and the key (switch SW 2  on), and sends a start signal to the RPG module through a buffer gate U 7 . 
     The transceiver module  15  transmits and receives a signal by infrared light communication to and from the key inserted. The reference character U 2  denotes an infrared light communication module, and the one used in the shown embodiment is a package of an infrared light emitting LED, a photodiode and a waveform shaping LSI. The reference character U 3 A denotes a monostable multivibrator which is supplied with the output pulse signal of the infrared light communication module as a trigger signal and sends an output pulse signal to the RPG module U 6 . Incidentally, the reference character U 4  denotes an AND circuit and U 5  denotes an inverter circuit to prevent the interference of the signals transmitted to and received from the infrared light communication module. The transceiver module may use a radio communication with light or radio wave other than the infrared light communication. 
     In the shown embodiment, the transmitting and receiving of the authentication data using the transceiver module is illustrated. Nevertheless, this invention is not limited to such means, but may use a circuit connection by contact as communication means (means for transmitting and receiving the authentication signal). 
     The RPG module  16 , which executes the communication procedures, sends out a signal, receives a signal and stores the data, has built therein a RPG providing a signal source. The RPG module also outputs an unlocking output to open the electronic lock when it is determined that the authentication data of the key body and the key are identical with each other. To open the electronic lock, well known means is used. In the case of an electromagnetic lock mechanism, for example, a control signal is sent to a control means to give an unlock instruction. The communication procedures between the key body and the key are described later. 
       FIG. 10  shows an example of configuration of the RPG module. This module is configured of a random pulse generator  16 A, an A/D converting circuit  16 B, a reference voltage generating circuit  16 C, a clock pulse generating circuit  16 D, a pulse counter  16 E, an input/output terminal (input/output circuit)  16 F, an arithmetic operation circuit (arithmetic operation, processing and control circuit)  16 G, a storage circuit  16 H, a display/operation sound output circuit  16 I and a lock operation output circuit  16 J. The arithmetic operation circuit  16 G determines whether the authentication signal input from the input/output terminal  16 F is identical with the authentication signal stored in the storage circuit  16 . The result of determination is displayed on the display/operation sound output circuit  16 I on the one hand and notified aurally from an external speaker, according to need. In the case of coincidence, an unlock output is produced through the lock operation output circuit. 
     The interval of the pulses output from the random pulse generator  16 A is random, and therefore, the pulse interval is calculated using the clock pulse generating circuit  16 D and the pulse counter  16 E. The number of clock pulses thus obtained is used as an authentication signal (authentication data). As an alternative, since the height value and the interval of the pulses output from the random pulse generator  16 A are random, the voltage of the height value is digitally converted using the A/D converting circuit  16 B and the reference voltage generation circuit  16 C, and the resulting digital signal is used as an authentication signal (authentication data). The embodiment shown in the drawing is so configured that the authentication signal can be obtained by any one or both of the methods described above. Nevertheless, only one of the configurations may be employed. 
     In registering a key, the authentication data obtained by the means described above is stored in the storage circuit  16 H, while at the same time being sent from the input/output terminal  16 F to the transceiver module  15  of the key body. The transceiver module sends the authentication data to the key, and stores it in an operation/storage module  24  through a transceiver module  23  of the key. 
     The RPG module  16  is not limited to the configuration shown in the drawing, but in accordance with the security level with which the key body (a lock) is mounted, can be replaced with a device having a CPU or a PIC that can construct a determining circuit or an internal clock. A one-chip configuration with ASIC is also possible. 
     The key inserted into the key body has built therein a circuit and a storage element to store the authentication signal, a circuit for transmitting and receiving the authentication signal corresponding to the communication mode, and if required, an antenna, a communication device and a power supply. The power can alternatively be supplied from an external source by communication (electromagnetic induction, radio wave or terminal connection). 
     The circuit configuration of the key paired with the key body is shown in  FIG. 7 . The key is configured of a power supply module  22 , the transceiver module  23  and the operation/storage module  24 . Incidentally, the key may have a shape and configuration like an IC card. 
     The power supply module  22  supplies the operation power to all the component circuits, and in the shown embodiment, is configured of a DC-DC converter U 1  to supply a stabilized voltage of 5 V. According to this embodiment, the power module  22  has such a configuration as to supply the signal power with a battery inserted therein. As an alternative, a switch may be built in to start communication as soon as it is depressed. 
     The transceiver module  23  is for transmitting and receiving a signal by infrared light communication with the key body. This configuration is similar to that of the transceiver module  15  of the key body. The output of the one-shot multivibrator U 3 A, however, is sent to the asynchronous receiving port of the operation/storage module  24 . 
     The operation/storage module  24  is a general-purpose PIC (peripheral interface controller) and has an arithmetic operation unit, a memory and an input/output unit. This operation/storage module  24  stores the authentication data and controls the communication between the key body and the key and the collation procedures of the authentication data. The module  24  according the embodiment shown in the drawing also includes a timer and a general-purpose communication port. 
     Next, the procedures of authenticating the key body and the key are started with registering the key as a partner side of authentication. In key registration, the key is automatically authenticated by insertion and can be registered as a partner side. In accordance with the safety level of the device and unit mounted, however, a fingerprint authentication device  2  or a ten-keys unit  3  (to input the pass word) as shown in  FIG. 1A  can also be combined. 
     To register the key, the key is inserted into the body of the electronic lock and a signal is written in the key from the RPG while at the same time being stored in the key body. 
     For authentication to open the lock, on the other hand, the authentication data sent from the registered key inserted into the key body is compared with the authentication data held in the key body. Upon coincidence of the authentication data, the lock is opened. Once the lock is opened, the data thereof is deleted while at the same time writing new authentication data in both the key body and the key. This authentication procedures and the storage of the authentication data are repeated each time the key is used. 
     The RPG (random pulse generator) can be so configured as to generate a random pulse by receiving the RF (radio wave) used in an IC tag, for example.  FIG. 11  shows a related embodiment. The RF is so weak that it is affected by the propagation conditions (environment, transmitting/receiving distance, or the like) and constitutes a substantially random signal from the viewpoint of e.g. the height value thereof. In  FIG. 11 , the RF ((a) of  FIG. 11 ) transmitted from the key body, the partner side or a RF transmitter  30  independent of them is received by a RPG  17  of the partner side or the key body. The RPG  17 , though plotted as a block different from the RPG module  16  in the shown embodiment, may of course be packaged in the RPG module  16 . According to this embodiment, the RPG  17  includes a RF receiver  17 A for receiving the RF, a RF dividing circuit  17 B (the output waveform of which is shown in (b) of  FIG. 11 ) for dividing (sampling) the RF height value (voltage) by the clock pulse, and an A/D converter  17 C for producing a random signal by A/D conversion of the divided height value ((c) of  FIG. 11 ). The output of the A/D converter  17 C is transmitted to the pulse counter  16 E of the RPG module  16  ( FIG. 10 ). According to this embodiment, the divided height value providing an output of the RF dividing circuit  17 B may be directly converted into a digital value by the A/D converting circuit  16 B of the RPG module  16 , and the resultant numerical value may be used. 
     In the authentication apparatus or the authentication method according to this invention, the key body or the partner side can include the computer hardware. Also, as a corresponding configuration, the RPG may be mounted on the partner side or the key body, and then mounted integrally or individually to the computer hardware. For example, the RPG is mounted on the computer or a peripheral device (such as a USB memory) connectable with the computer to execute the authentication between the computer and the peripheral device using a random authentication signal. 
     The authentication steps according to the invention can be programmed. Such an authentication program can be installed in the body, the partner side, or each of them, and it includes, for example, a code to generate random pulses from a random pulse generator arranged in the body or the partner side paired with the body, or in both the key body and the partner side, a code to output authentication data based on the random pulse generated by the RPG, a code to store authentication data, a code to transmit/receive authentication data and a code to control the communication of authentication data and collate authentication data. 
     Also, the program to control the communication of authentication data and collate authentication data includes, for example, a code to receive authentication data stored in a storage means stored on the partner side, a code to collate the received authentication data with authentication data of a storage means arranged in the body, a code to authenticate the partner side in accordance with the collation result, a code to update authentication data after completion of authentication and a code to write thus updated new authentication data in the storage means of the body and the partner side. 
     The communication procedures between the key body and the key constituting the partner side are shown in detail in  FIG. 8 .
     (i) The key body, upon detection of the key insertion by an insertion detection trigger module, sends the character key I(inquire)↓ (I command) to the key constituting the partner side thereby to request the transmission of the collation data.   (ii) The key, upon receipt of the I command from the key body, transmits the stored collation data to the key body with a character string “Rx . . . x↓” (x . . . x changes with the RPG data).   (iii) The key body, upon receipt of the collation data from the key, compares it with the data held in the key body, and upon incoincidence, generates a NG sound to end the authentication process.   (iv) Upon coincidence in (iii), on the other hand, an unlock output from the RPG module is sent to an appropriate drive control circuit to open the electronic lock. At the same time, the RPG module updates the authentication data (interval data of about 100 μsec) and transmits it to the key as a new authentication data in the command form of Wx . . . x↓”.   (v) Upon receipt of the W command, the key holds the new data for the next collation.   (vi) In order to check whether the authentication data sent by the W command is received rightly by the key, the key body transmits the I command again to the key.   (vii) In response to the I command, the key returns the new authentication data to the key body with the R command.   (viii) The key body collates the received authentication data, and upon coincidence, considers the process as a success and generates an OK sound.   (ix) Upon incoincidence in (viii), on the other hand, the data is transmitted again to the key as the W command. Subsequently, the steps (v) to (viii) are repeated several times, and if the process still ends in a failure, a fatal error sound is issued thereby to end the authentication process.   

     In the case of the fatal error, the authentication data held by the key body and the key remain different from each other, and therefore could not be used permanently as they are. To avoid this inconvenience, according to this invention, the process is initialized according to the steps described below to forcibly enable both units to hold the same data.
     (i) The 20 pins of the RPG module are shorted to GND.   (ii) The key is inserted into a lever switch (insertion detection trigger module).   (iii) The initialization is successful if the OK sound is generated.   

     These steps used in this method are illustrative, and the initialization is possible also by another process. In any way, it is important to select a method by which safety can be secured. 
     INDUSTRIAL APPLICABILITY 
     An example in which the RPG is built in the body of the electronic lock is explained above. This invention, however, is not limited to such a configuration and applicable to an IC tag, or the like. The RPG can be incorporated in the body, the partner side or both the body and the partner side. Also, the communication procedures and the authentication procedures between the key body and the partner side can of course be changed in accordance with the arrangement of the RPG, the memory and the communication/authentication control units.