Mutual authentication method and authentication device for providing method

Abstract

The present invention relates to a mutual authentication method and an authentication device for providing the method, and an authentication device of the present invention comprises: an authentication communication unit for receiving first identification information from an electronic device that requests primary authentication; an authentication storage unit for storing second identification information, a one-way encryption algorithm, a random number generation algorithm, and an initial vector inputted during operation of the random number generation algorithm; and an authentication control unit, which compares the first identification information with the second identification information to verify the first identification information, and determines whether to approve the primary authentication according to the verification result, wherein, if the primary authentication is approved, the authentication control unit encrypts the second identification information with the one-way encryption algorithm to generate authentication encryption text, and transmits the authentication encryption text to the electronic device to request secondary authentication, and, if a first random number is received from the electronic device in response to the secondary authentication request, inputs the second identification information and the initial vector into the random number generation algorithm to generate a second random number, compares the first random number with the second random number to verify the first random number, and determines whether to approve the secondary authentication according to the verification result.

Description

BACKGROUND OF THE INVENTION(a) Field of the InventionThe present invention relates to a cross certification method and acertifying device for providing the method.(b) Description of the Related ArtRecently, rechargeable batteries are widely used in mobile devices suchas laptops or mobile phones, various power transportation vehicles such aselectric bicycles, electric vehicles, or hybrid vehicles, power backup devices forsupplying power in case of blackouts, and large-capacity power storage devicesfor storing large-capacity power in advance and supplying power to otherdevices.Particularly, regarding devices for supplying a huge amount of power orstoring the same such as for electric vehicles (EV) or energy storage systems(ESS), a battery is configured with a battery cell that is a rechargeable battery, abattery module in which a plurality of battery cells are connected in series, anda battery pack in which a plurality of battery modules are connected in seriesand / or in parallel.Particularly, the battery pack is managed by a battery managementsystem (BMS). The battery management system (BMS) maintains andmanages the battery by monitoring a voltage, a current, and a temperature ofthe battery pack. The battery management system (BMS) manages thebattery system including the battery and its peripheral devices by, for example,predicting a replacement time of the battery and checking battery drawbacks inadvance.There are attempts to store various data collected by the batterymanagement system (BMS) for the purpose of research and development in aremote central server. However, transmission and storage of data through aradio network have problems such as security and certification. That is,solutions to the drawbacks including certifying of a data transmitting device anda data receiving and storing device, and security against external maliciousattacks are needed.SUMMARY OF THE INVENTIONThe present invention has been made in an effort to provide a crosscertification method for an electronic device and a certifying device torespectively request a certification, approve the requested certification, andaccordingly perform a cross certification, and a certifying device for providingthe method.An embodiment of the present invention provides a certifying deviceincluding: a certification communication unit configured to receive firstidentification information from an electronic device requesting a firstcertification; a certification storage unit configured to store second identificationinformation, a unidirectional encryption algorithm, a random number generatingalgorithm, and an initial vector that is input when the random number generatingalgorithm is operated; and a certification control unit configured to compare thefirst identification information and the second identification information to verifythe first identification information, and determine whether to approve the firstcertification according to a result of the verification, wherein when the firstcertification is approved, the certification control unit encrypts the secondidentification information with the unidirectional encryption algorithm to generatea certification cryptogram, and transmits the certification cryptogram to theelectronic device to request a second certification, when receiving a firstrandom number from the electronic device in response to the request for thesecond certification, the certification control unit inputs the second identificationinformation and the initial vector to the random number generating algorithm togenerate a second random number, and the certification control unit comparesthe first random number and the second random number to verify the firstrandom number, and determines whether to approve the second certificationaccording to a result of the verification.The certification control unit may decrypt data that are encrypted with afirst key of a bidirectional encryption algorithm with a second key of thebidirectional encryption algorithm, and may transmit the data encrypted with thesecond key to the electronic device.The first key may be a private key, and the second key may be a publickey.The first identification information and the second identificationinformation may respectively include a serial number of the electronic deviceand a serial number of the certifying device.The certification control unit may block a network access to theelectronic device when the first identification information and the secondidentification information do not correspond to each other or when the firstrandom number and the second random number do not correspond to eachother.Another embodiment of the present invention provides a crosscertification method for a certifying device to perform a cross certification withan electronic device including same certification information, the methodincluding: receiving first identification information from the electronic devicerequesting a first certification; comparing the first identification information andstored second identification information to verify the first identificationinformation; when the first identification information and the secondidentification information are found to correspond to each other and passverification according to a result of the comparison, encrypting the secondidentification information with a unidirectional encryption algorithm to generate acertification cryptogram; transmitting the certification cryptogram to theelectronic device to request a second certification; receiving a first randomnumber from the electronic device in response to the request for the secondcertification; inputting an initial vector that is input when a random numbergenerating algorithm is operated and the second identification information to therandom number generating algorithm to generate a second random number;comparing the first random number and the second random number; and whenthe first random number and the second random number are found tocorrespond to each other according to a result of the comparison, determiningwhether to approve the second certification.The certifying device may decrypt data that are encrypted with a first keyof a bidirectional encryption algorithm with a second key of the bidirectionalencryption algorithm, and may transmit the data encrypted with the second keyto the electronic device.The first key may be a private key, and the second key may be a publickey.The first identification information and the second identificationinformation may respectively include a serial number of the electronic deviceand a serial number of the certifying device.The cross certification method may further include, after the verifying offirst identification information, blocking a network access to the electronic devicewhen the first identification information and the second identification informationare found to not correspond to each other according to a result of thecomparison.The cross certification method may further include, after the comparingof the first random number and the second random number, blocking a networkaccess to the electronic device when the first random number and the secondrandom number are found to not correspond to each other.The present invention may identify the respective devices performing across certification, and may provide the certification method and device withhigh reliability.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 shows a certification system according to an embodiment.FIG. 2 shows a configuration of an electronic device of FIG. 1.FIG. 3 shows a configuration of a certifying device of FIG. 1.FIG. 4 shows a flowchart of a certification method according to anembodiment.FIG. 5 shows a flowchart of operations of an electronic device and acertifying device for performing a certification method of FIG. 4.DETAILED DESCRIPTION OF THE EMBODIMENTSHereinafter, embodiments disclosed in the present specification will bedescribed in detail with reference to the accompanying drawings. In thepresent specification, the same or similar components will be denoted by thesame or similar reference numerals, and an overlapped description thereof willbe omitted. The terms "module" and "unit" for components used in thefollowing description are used only in order to make the specification easier.Therefore, these terms do not have meanings or roles that distinguish themfrom each other by themselves. In describing embodiments of the presentspecification, when it is determined that a detailed description of the well-knownart associated with the present invention may obscure the gist of the presentinvention, it will be omitted. The accompanying drawings are provided only inorder to allow embodiments disclosed in the present specification to be easilyunderstood and are not to be interpreted as limiting the spirit disclosed in thepresent specification, and it is to be understood that the present inventionincludes all modifications, equivalents, and substitutions without departing fromthe scope and spirit of the present invention.Terms including ordinal numbers such as first, second, and the like, willbe used only to describe various components, and are not interpreted aslimiting these components. The terms are only used to differentiate onecomponent from others.It is to be understood that when one component is referred to as being"connected" or "coupled" to another component, it may be connected or coupleddirectly to another component or be connected or coupled to anothercomponent with the other component intervening therebetween. On the otherhand, it is to be understood that when one component is referred to as being"connected or coupled directly" to another component, it may be connected orcoupled to another component without the other component interveningtherebetween.It will be further understood that terms "comprises" or "have" used in thepresent specification specify the presence of stated features, numerals, steps,operations, components, parts, or a combination thereof, but do not precludethe presence or addition of one or more other features, numerals, steps,operations, components, parts, or a combination thereof.A "network" signifies a connecting structure for respective mutual nodessuch as terminals and servers to exchange information, and includes the localarea network (LAN), the wide area network (WAN), the Internet (WWW: WorldWide Web), wired / wireless data communication networks, telephone networks,and wired / wireless television communication networks. Examples of the datacommunication networks include the 3G, 4G, 5G, 3rd generation partnershipproject (3GPP), long term evolution (LTE), world interoperability for microwaveaccess (WIMAX), Wi-Fi, Bluetooth communication, infrared ray communication,5 ultrasonic wave communication, visible light communication (VLC), and LiFi.FIG. 1 shows a certification system according to an embodiment.Referring to FIG. 1, the certification system 1 includes an electronicdevice 20 and a certifying device 30.A battery management system (BMS) 10 shown in FIG. 1 monitors a cellvoltage, a current, and a temperature of a battery pack (not shown) in real timeto adjust a voltage among a plurality of battery cells to be uniform, and preventsexcessive charging / discharging to manage the battery to be in an optimizedstate. The battery management system (BMS) 10 may estimate a state ofcharge (SOC) and a state of health (SOH) of the battery. In this instance,information generated in the battery system including the measured cellvoltages, currents, and temperatures, and the estimated SOC and SOH aredefined to be battery data (hereinafter, data). The device for generating data isillustrated to be the battery management system (BMS) 10 in FIG. 1, andwithout being limited thereto, it may include a device for generating data inmany fields.The electronic device 20 performs a cross certification with the certifyingdevice 30 before transmitting data to the remote certifying device 30.According to an embodiment, the electronic device 20 may configure the batterysystem together with the battery management system (BMS) 10, and may beincluded in various types of systems such as the electric vehicle (EV) or theenergy storage system (ESS).The certifying device 30 performs a cross certification with the electronicdevice 20 before receiving data and storing the data. According to anembodiment, the certifying device 30 may configure a storage system togetherwith a database (not shown), and may be included in various sorts of systemssuch as a server or a data center.FIG. 2 shows a configuration of an electronic device of FIG. 1.Referring to FIG. 2, the electronic device 20 includes a devicecommunication unit 21, a device storage unit 23, and a device control unit 25.The device communication unit 21 may include a first communicationmodule for communicating with the battery management system (BMS) 10 anda second communication module for communicating with the certifying devicethrough a radio network.The first communication module may include a communication protocolfor communication among devices in the electric vehicle (EV) and may receivedata from the battery management system (BMS) 10. For example, the firstcommunication module may include a controller area network (CAN)communication module, a local interconnect network (LIN) communicationmodule, or a FlexRay communication module.The second communication module may transmit / receive data to / fromthe certifying device 30 through the radio network. For example, the secondcommunication module may include a radio Internet module such as thewireless LAN (WLAN), the Wi-Fi, the wireless broadband (WiBro), the worldinteroperability for microwave access (WiMAX), or high speed downlink packetaccess (HSDPA).The device storage unit 23 may include a first region for storing firstcertification information for a cross certification and a second region fortemporarily storing the data received from the battery management system(BMS) 10. According to another embodiment, the data generated by thebattery management system (BMS) 10 are not temporality stored in the secondregion of the device storage unit 23, and when the cross certification issuccessful, the data may be transmitted to the certifying device 30.The device storage unit 23 may include at least one type of storagemedium from among a flash memory type, a hard disk type, a multimedia cardmicro type, a card type memory (e.g., an SD or XD memory), a random accessmemory (RAM), a static random access memory (SRAM), a read-only memory(ROM), an electrically erasable programmable read-only memory (EEPROM), aprogrammable read-only memory (PROM), a magnetic memory, a magneticdisk, and an optical disc.The first certification information may include first identificationinformation for identifying devices that transmit and receive data, a bidirectionalencryption algorithm, a unidirectional encryption algorithm, a random numbergenerating algorithm, and an initial vector that is input when a random numbergenerating algorithm is operated. According to an embodiment, the firstcertification information may include the same information as the secondcertification information.The first identification information may include a serial number of thedevice for transmitting data after the cross certification is approved. Forexample, the serial number of the device for transmitting data may include oneof a serial number of the electronic device 20, a serial number of the batteryfrom which data will be collected, and a serial number of the batterymanagement system (BMS) 10 for collecting data.The first identification information may include a serial number of thedevice for receiving data and storing the data after the cross certification isapproved. For example, the serial number of the device for receiving data andstoring the data may include one of a serial number of the certifying device 30,and a serial number of the server or the data center for storing the data.According to an embodiment, the first identification information mayinclude a serial number of the electronic device 20 and a serial number of thecertifying device 30. That is, the first identification information may includeidentification information of a first side and a second side for performing a crosscertification.The bidirectional encryption algorithm is an encryption algorithm forencryption and decryption. The data transmitted and received whenperforming a cross certification between the electronic device 20 and thecertifying device 30 may be encrypted by the bidirectional encryption algorithmand may be transmitted. According to an embodiment, the electronic deviceand the certifying device 30 may use an asymmetric key type of bidirectionalencryption algorithm using different keys for encryption and decryption.For example, the electronic device 20 may use a private key to performencryption and decryption, and the certifying device 30 may use a public key toperform encryption and decryption.In detail, the electronic device 20 transmits a cryptogram generated byencrypting data with a private key to the certifying device 30. The certifyingdevice 30 may decrypt the cryptogram with a public key to restore the data.The certifying device 30 transmits the cryptogram generated by encrypting thedata with a public key to the electronic device 20. The electronic device 20may decrypt the cryptogram with a private key to restore the data.For another example, the electronic device 20 may perform encryptionand decryption by using a public key, and the certifying device 30 may performencryption and decryption by using a private key.The unidirectional encryption algorithm may perform encryption and maynot perform decryption. In detail, the same data are encrypted into the samecryptogram, but the cryptogram may not be restored into the data. Forexample, the data may be certified by a verifying process for respectivelyencrypting the same data with the same unidirectional encryption algorithm andmutually comparing the encrypted values. The unidirectional encryptionalgorithm generally uses a hash scheme which is SHA-256 or SHA-3.The random number generating algorithm may generate pseudorandom numbers. Random numbers represent values that are randomlyextracted within a defined range, no generation method thereof is determined,and values to be generated next are not predicted at all. The pseudo-randomnumbers represent numbers that are generated by a predetermined mechanism(a pseudo-random number generator) by using an initially provided input value(an initial value), and they are not real random numbers but are arbitrarynumbers that may be considered as random numbers without problems whenused.For example, the pseudo-random numbers may be generated by acomputer using the random number generating algorithm. When a generationcondition or the input value is the same, the pseudo-random numbers that areresultant values thereof are always the same. When a seed value that is theinput value is changed to have a different value, a resultant pseudo-randomnumber is also changed, and the pseudo-random number has the meaning ofthe random number. The seed value may use a present time that changesevery moment. The pseudo-random number will be described as a randomnumber hereinafter.According to an embodiment, the device control unit 25 may generate afirst random number by setting an initial vector that is an initial value used whenthe random number generating algorithm is operated and first identificationinformation as seed values, and using the present time. The device controlunit 25 may calculate the present time based on a reference time that is thetime when the electronic device 20 is first operated and a number of countingticks at predetermined intervals.According to an embodiment, the device control unit 25 performs across certification with the certifying device 30 by using first certificationinformation stored in the first region of the device storage unit 23. When thecross certification is successful, the device control unit 25 may transmit the datastored in the second region of the device storage unit 23 to the certifying device30. That is, the device control unit 25 may perform a cross certification withthe certifying device 30, and may transmit the data to the certifying device 30.According to another embodiment, the device control unit 25 performs across certification with the certifying device 30 by using first certificationinformation stored in the first region of the device storage unit 23. When thecross certification is successful, the device control unit 25 may transmit a crosscertification result to the battery management system (BMS) 10. The batterymanagement system (BMS) 10 may transmit the data to the certifying device 30.That is, the device control unit 25 may perform a cross certification with thecertifying device 30, and the battery management system (BMS) 10 maytransmit the data to the certifying device 30.FIG. 3 shows a configuration of a certifying device of FIG. 1.Referring to FIG. 3, the certifying device 30 includes a certificationcommunication unit 31, a certification storage unit 33, and a certification controlunit 35.The certification communication unit 31 may transmit / receive datato / from the electronic device 20 through the radio network. For example, thecertification communication unit 31 may include a radio Internet module such asthe wireless LAN (WLAN), the Wi-Fi, the wireless broadband (WiBro), the worldinteroperability for microwave access (WiMAX), or the high speed downlinkpacket access (HSDPA).The certification storage unit 33 may store second certificationinformation for the cross certification. The certification storage unit 33 mayinclude at least one type of storage medium from among a flash memory type, ahard disk type, a multimedia card micro type, a card type memory (e.g., an SDor XD memory), a random access memory (RAM), a static random accessmemory (SRAM), a read-only memory (ROM), an electrically erasableprogrammable read-only memory (EEPROM), a programmable read-onlymemory (PROM), a magnetic memory, a magnetic disk, and an optical disc.According to an embodiment, the server or the data center may includea database (DB) for storing the data transmitted from the electronic device 20after success of the cross certification through the certifying device 30. Forexample, the server or the data center may store large-capacity battery datatransmitted at predetermined intervals or in real time from a plurality of batterymanagement systems (BMS) mounted on a plurality of electric vehicles (EV) inthe database (DB).The second certification information may include second identificationinformation for identifying devices that transmit and receive data, a bidirectionalencryption algorithm, a unidirectional encryption algorithm, a random numbergenerating algorithm, and an initial vector that is input when a random numbergenerating algorithm is operated. According to an embodiment, the secondcertification information may include the same information as the firstcertification information stored in the electronic device 20.According to an embodiment, the second identification information mayinclude a serial number of the electronic device 20 and a serial number of thecertifying device 30. That is, the second identification information may includeidentification information on the first side and the second side for performing across certification. For example, the second identification information mayinclude the same identification information as the first identification information.The certification control unit 35 performs a cross certification with theelectronic device 20 by using the second certification information stored in thecertification storage unit 33. When the cross certification is successful, thecertification control unit 35 may transmit a cross certification result to a centralcontrol unit (not shown) of the server or the data center. The central controlunit (not shown) may maintain a network access to the electronic device 20,and may store the data transmitted from the electronic device 20 in thedatabase (DB).FIG. 4 shows a flowchart of a certification method according to anembodiment.The electronic device 20 and the certifying device 30 perform a crosscertification. Here, differing from a single certification method for, when oneside requests a certification and another side verifies it and determines anapproval of certification or a rejection of certification, the cross certificationrepresents a certification method for the electronic device 20 and the certifyingdevice 30 to determine an approval of certification or a rejection of certificationon the request of certification from the other side. According to anembodiment, the electronic device 20 and the certifying device 30 may store thesame certification information and encryption algorithm, and may perform thecross certification based upon the same.Referring to FIG. 4, when the electronic device 20 encrypts firstidentification information with the first key of the bidirectional encryptionalgorithm and transmits the encrypted first identification information to thecertifying device 30 to request a first certification, the certifying device 30determines whether to approve the first certification (S110).The electronic device 20 may encrypt the first identification informationwith a private key and may transmit the same to the certifying device 30. Thefirst identification information may include a serial number of the electronicdevice 20 and a serial number of the certifying device 30. The electronicdevice 20 may encrypt the first identification information with a public key andmay transmit the same to the certifying device 30.For example, when the electronic device 20 uses the private key as afirst key, the certifying device 30 may use the public key as a second key.When the electronic device 20 uses the public key as a first key, the certifyingdevice 30 may use the private key as a second key. The electronic device 20and the certifying device 30 may then respectively decrypt the receivedencrypted information with their own keys.The certifying device 30 compares the first identification information andthe stored second identification information and determines whether to approveor reject the first certification (S120).The certifying device 30 decrypts the encrypted first identificationinformation with the second key of the bidirectional encryption algorithm.According to an embodiment, the certifying device 30 compares the serialnumber of the electronic device 20 and the serial number of the certifyingdevice 30 included in the first identification information and the stored secondidentification information, that is, the serial number of the stored electronicdevice 20 and the serial number of the certifying device 30, to determinewhether they correspond to each other.When they are found to correspond to each other according to acomparison result, the first certification is approved (S120, Yes), the certifyingdevice 30 encrypts the second identification information with the unidirectionalencryption algorithm to generate a certification cryptogram, and transmits thecertification cryptogram to the electronic device 20 to request a secondcertification (S130).According to an embodiment, the certifying device 30 may encrypt thecertification cryptogram with the second key of the bidirectional encryptionalgorithm and may transmit the same to the electronic device 20. That is, thecertifying device 30 may first-encrypt the second identification information withthe unidirectional encryption algorithm, may second-encrypt the certificationcryptogram generated by the first encryption with the second key of thebidirectional encryption algorithm, and may transmit a result to the electronicdevice 20.The certifying device 30 may encrypt the data with the second key of thebidirectional encryption algorithm and may transmit the same to the electronicdevice 20 in a final stage of transmitting the data. The certifying device 30may decrypt the data that are encrypted with the first key of the bidirectionalencryption algorithm and are received with the second key of the bidirectionalencryption algorithm.The electronic device 20 decrypts the certification cryptogram encryptedwith the second key and received, with the first key. The electronic device 20encrypts the first identification information with the unidirectional encryptionalgorithm to generate a device cryptogram. When the electronic device 20 andthe certifying device 30 use the same unidirectional encryption algorithm, andthe first identification information and the second identification information arethe same, the certification cryptogram and the device cryptogram have thesame value because of a characteristic of the unidirectional encryptionalgorithm.The electronic device 20 compares the certification cryptogram and thedevice cryptogram to verify the certification cryptogram. When they are foundto correspond to each other according to a comparison result, the electronicdevice 20 inputs the initial vector and first identification information to therandom number generating algorithm to generate a first random number, andencrypts the generated first random number with the first key. The firstidentification information input as the seed value is the serial number of theelectronic device 20 or the serial number of the certifying device 30, and it maybe a serial number that is predefined by the certifying device 30.The electronic device 20 transmits the first random number encryptedwith the first key to the certifying device 30 in response to the request of secondcertification. The certifying device 30 inputs the stored initial vector and thesecond identification information to the random number generating algorithm togenerate a second random number. The second identification informationinput as the seed value is the serial number of the electronic device 20 or theserial number of the certifying device 30, and it may be a serial number that ispredefined by the electronic device 20.The certifying device 30 decrypts the first random number with thesecond key and compares it with the second random number to determinewhether they correspond to each other (S140).That is, the certifying device 30 may request a second certification fromthe electronic device 20, and may determine whether to approve the secondcertification based on the response to the request.When they are found to correspond to each other according to a resultof determination (S140, Yes), the certifying device 30 approves the secondcertification (S150). The network access of the electronic device 20 and thecertifying device 30 is maintained, and when the electronic device 20 transmitsdata, the certifying device 30 may receive the data and may store the same.When they are found to not correspond to each other according to theresult of determination (S140, No), the certifying device 30 rejects the secondcertification and blocks the network access of the electronic device 20 and thecertifying device 30 (S160).FIG. 5 shows a flowchart of operations of an electronic device and acertifying device for performing a certification method of FIG. 4.FIG. 5 shows a detailed drawing of FIG. 4. A cross certification methodwill now be described with reference to FIG. 1 to FIG. 5.Referring to FIG. 5, the electronic device 20 encrypts the firstidentification information with the first key of the bidirectional encryptionalgorithm and transmits the same to the certifying device 30 to request a firstcertification (S201 and S202).The electronic device 20 may encrypt the first identification informationwith the private key and may transmit the same to the certifying device 30.The first identification information may include the serial number of theelectronic device 20 and the serial number of the certifying device 30.The certifying device 30 compares the first identification information andthe stored second identification information to verify the first identificationinformation (S203).The certifying device 30 decrypts the encrypted first identificationinformation with the second key of the bidirectional encryption algorithm. Forexample, the certifying device 30 may decrypt the first identification informationwith the public key.According to an embodiment, the certifying device 30 may compare theserial number of the electronic device 20 and the serial number of the certifyingdevice 30 included in the first identification information and the stored secondidentification information, that is, the serial number of the stored electronicdevice 20 and the serial number of the certifying device 30, and may determinewhether they correspond to each other.When they are found to correspond to each other and pass theverification according to a result of comparison (S204, Yes), the certifyingdevice 30 approves the first certification (S205).The certifying device 30 encrypts the second identification informationwith the unidirectional encryption algorithm to generate a certificationcryptogram, encrypts the certification cryptogram with the second key, andtransmits the encrypted certification cryptogram to the electronic device 20 torequest a second certification (S206 and S207).According to an embodiment, the certifying device 30 may encrypt thecertification cryptogram with the second key of the bidirectional encryptionalgorithm and may transmit the encrypted certification cryptogram to theelectronic device 20. That is, the certifying device 30 may first-encrypt thesecond identification information with the unidirectional encryption algorithm,may second-encrypt the certification cryptogram generated by the firstencryption with the second key of the bidirectional encryption algorithm, andmay transmit a result to the electronic device 20.The certifying device 30 may encrypt the data with the second key of thebidirectional encryption algorithm and may transmit the same to the electronicdevice 20 in a final stage of transmitting the data. The certifying device 30may decrypt the data that are encrypted with the first key of the bidirectionalencryption algorithm and are received with the second key of the bidirectionalencryption algorithm.The electronic device 20 encrypts the first identification information withthe unidirectional encryption algorithm to generate a device cryptogram, andcompares the received certification cryptogram and the device cryptogram toverify the certification cryptogram (S208).When the electronic device 20 and the certifying device 30 use thesame unidirectional encryption algorithm, and the first identification informationand the second identification information are the same, the certificationcryptogram and the device cryptogram have the same value because of acharacteristic of the unidirectional encryption algorithm.The electronic device 20 decrypts the certification cryptogram encryptedwith the second key and received, with the first key. The electronic device 20compares the certification cryptogram and the device cryptogram to verify thecertification cryptogram.When they are found to correspond to each and pass the verificationaccording to a result of comparison (S209, Yes), the electronic device 20 inputsthe first identification information and the initial vector to the random numbergenerating algorithm to generate a first random number (S210). The firstidentification information input as the seed value is the serial number of theelectronic device 20 or the serial number of the certifying device 30, and it maybe a serial number that is predefined by the certifying device 30.The electronic device 20 encrypts the first random number with the firstkey and transmits the encrypted first random number to the certifying device 30in response to the request of second certification (S211).When they are found to not correspond to each other and they fail topass the verification according to a result of comparison (S209, No), theelectronic device 20 blocks the network access to the certifying device 30(S216). For example, the electronic device 20 may determine the certifyingdevice 30 to be unreliable, and it may not transmit various types of data such asbattery data to the certifying device 30.The certifying device 30 inputs the second identification information andthe initial vector to the random number generating algorithm to generate asecond random number (S212). The second identification information input asthe seed value is the serial number of the electronic device 20 or the serialnumber of the certifying device 30, and it may be a serial number that ispredefined by the electronic device 20.The certifying device 30 decrypts the first random number with thesecond key and compares the decrypted first random number with the secondrandom number to determine whether they correspond to each other (S213).When they are found to correspond to each other according to a resultof determination (S213, Yes), the certifying device 30 approves the secondcertification (S214).According to an embodiment, the certifying device 30 may request asecond certification from the electronic device 20, and may determine whetherto approve the second certification based on the response to the request.When the second certification is approved, the network access of the electronicdevice 20 and the certifying device 30 is maintained, and when the electronicdevice 20 transmits data, the certifying device 30 may receive the data and maystore the same.When the first identification information and second identificationinformation do not correspond to each other and fail to pass the verificationaccording to a result of comparison (S204, No) or when they do not correspondto each other according to a result of determination (S213, No), the certifyingdevice 30 determines whether to reject the first certification or reject the secondcertification, and to block the network access of the electronic device 20 and thecertifying device 30 (S215).While this invention has been described in connection with what ispresently considered to be practical embodiments, it is to be understood thatthe invention is not limited to the disclosed embodiments, but, on the contrary, isintended to cover various modifications and equivalent arrangements includedwithin the spirit and scope of the appended claims.

Claims

1. A certifying device comprising: a certification communication unit configured to receive first identification information from an electronic device requesting a first certification; a certification storage unit configured to store second identification information, a unidirectional encryption algorithm, a random number generating algorithm, and an initial vector that is input when the random number generating algorithm is operated; and a certification control unit configured to compare the first identification information and the second identification information to verify the first identification information, and determine whether to approve the first certification according to a result of the verification, wherein: when the first certification is approved, the certification control unit encrypts the second identification information with the unidirectional encryption algorithm to generate a certification cryptogram, and transmits the certification cryptogram to the electronic device to request a second certification, when receiving a first random number from the electronic device in response to the request for the second certification, the certification control unit inputs the second identification information and the initial vector to the random number generating algorithm to generate a second random number, and the certification control unit compares the first random number and the second random number to verify the first random number, and determines whether to approve the second certification according to a result of the verification.

2. The certifying device of claim 1, wherein the certification control unit decrypts data that are encrypted with a first key of a bidirectional encryption algorithm with a second key of the bidirectional encryption algorithm, and transmits the data encrypted with the second key to the electronic device.

3. The certifying device of claim 2, wherein the first key is a private key, and the second key is a public key.

4. The certifying device of claim 2, wherein the first identification information and the second identification information respectively include a serial number of the electronic device and a serial number of the certifying device.

5. The certifying device of claim 1, wherein the certification control unit blocks a network access to the electronic device when the first identification information and the second identification information do not correspond to each other or when the first random number and the second random number do not correspond to each other.

6. A cross certification method for a certifying device to perform a cross certification with an electronic device including same certification information, the method comprising: receiving first identification information from the electronic device requesting a first certification; comparing the first identification information and stored second identification information to verify the first identification information; when the first identification information and the second identification information are found to correspond to each other and pass verification according to a result of the comparison, encrypting the second identification information with a unidirectional encryption algorithm to generate a certification cryptogram; transmitting the certification cryptogram to the electronic device to request a second certification; receiving a first random number from the electronic device in response to the request for the second certification; inputting an initial vector that is input when a random number generating algorithm is operated and the second identification information to the random number generating algorithm to generate a second random number; comparing the first random number and the second random number; and when the first random number and the second random number are found to correspond to each other according to a result of the comparison, determining whether to approve the second certification.

7. The cross certification method of claim 6, wherein the certifying device decrypts data that are encrypted with a first key of a bidirectional encryption algorithm with a second key of the bidirectional encryption algorithm, and transmits the data encrypted with the second key to the electronic device.

8. The cross certification method of claim 7, wherein the first key is a private key, and the second key is a public key.

9. The cross certification method of claim 7, wherein the first identification information and the second identification information respectively include a serial number of the electronic device and a serial number of the certifying device.

10. The cross certification method of claim 6, further comprising, after the verifying of first identification information, blocking a network access to the electronic device when the first identification information and the second identification information are found to not correspond to each other according to a result of the comparison.

11. The cross certification method of claim 6, further comprising, after the comparing of the first random number and the second random number, blocking a network access to the electronic device when the first random number and the second random number are found to not correspond to each other.