KR100734885B1 - Method for authenticating RFID tag and RFID server each other - Google Patents

Abstract

In the method of mutual authentication of an RFID tag and an RFID server according to the present invention, a method of authenticating an RFID server by an RFID tag includes a method in which an RFID tag performs mutual authentication with an RFID server, and the first to third secret keys of the RFID server. Sharing a plurality of secret keys including their fourth to sixth secret keys; Setting a private key retention state and transmitting the request according to a request of an RFID server; Authenticating the RFID server by receiving the server authentication information generated by the RFID server based on a predetermined random number and secret keys; Transmitting, by the RFID server, tag authentication information for authenticating the RFID tag if the server is an authenticated RFID server; And updating the secret keys that have been received and maintained by the RFID server when the authentication is successful and the secret key update information is transmitted. The implementation is based on a relatively short secret key and an exclusive-OR operation function. Since it is possible, it can be applied to a passive RFID tag that does not have its own power source, and can be spread to various RFID fields that require authentication by producing a tag at a low manufacturing cost.

RFID tag, secret key

Description

Method for mutual authentication of RFID server and RFID tag {Method for authenticating RFID tag and RFID server each other}

1 is a block diagram showing an RFID authentication network structure to which the present invention is applied.

2 is a flowchart illustrating a process in which an RFID tag authenticates an RFID server according to the present invention.

3 is a flowchart illustrating a process of authenticating an RFID tag by an RFID server according to the present invention.

4 is a flowchart illustrating a mutual authentication process between an RFID server and an RFID tag according to the present invention.

5 is a flowchart illustrating an operation of the RFID tag of FIG. 2 in more detail.

6 is a flowchart illustrating an operation of an RFID tag authentication server of FIG. 3 in more detail.

7 is a command and message format to be added to the EPC GEN2 standard.

The present invention relates to a method for mutual authentication between an RFID tag and an RFID server, and more particularly, an RFID tag and an RFID tag authentication server sharing a secret key determine the legitimacy or authenticity of an RFID tag by verifying mutual secret keys. Relates to how to do it.

RFID began as a field of automatic recognition technology to replace barcodes used to identify objects. RFID enters unique information into tags attached to all objects including people, reads this information through readers, and integrates with information systems in connection with existing satellites, mobile communication networks and Internet networks. RFID has a number of advantages over barcodes. RFID may have its own memory that can store information other than the identification code, and does not affect whether the field of view or packaging material is recognized, and transmits information in a wireless section, and has a relatively long recognition distance. These features enable more diverse forms of application services in simple object identification. It is spreading to infinite application areas such as automation of manufacturing process, inventory management, shipment control, animal tracking, container identification (e-seal) and ticketing. RFID systems applied in manufacturing, logistics, and distribution networks are tagged with goods, and performed by humans in inventory management, shipment and receipt management, and goods tracking that occur during the existing production and distribution process through contactless and wireless communication. Not only is it cumbersome and time consuming, but the result also enables the transformation of highly inaccurate tasks into automated, accurate and efficient tasks.

RFID tag is composed of simple control circuit without CPU, memory and transmit / receive antenna. Due to the non-contact wireless communication characteristic of the RFID, it is possible to easily collect and duplicate tag information using a reader. RFID technology is expanding its application area to prevent identification and product forgery and alteration. Complex cryptographic algorithms are commonly used to provide secure application services. However, due to the limited computational power of RFID tags and constraints to lower the tag manufacturing cost, the RFID technology field makes it difficult to apply to various security application services.

The technical problem to be achieved by the present invention is a method of authenticating an RFID server by providing a simple operation method for exchanging and verifying a secret key having a short length in a tag-based RFID system with limited computing power and resources, and a simple operation method therefor. To provide.

Another technical problem to be achieved by the present invention is to provide a simple operation method for exchanging and verifying a secret key having a short length in a tag-based RFID system having limited computational power and resources, and an RFID server to authenticate an RFID tag. To provide a method.

Another technical problem to be solved by the present invention is to exchange and verify a secret key having a short length in a tag-based RFID system with limited computing power and resources, and to provide a simple operation method for the mutual communication between the RFID tag and the RFID server. To provide an authentication method.

In order to achieve the above technical problem, a method of authenticating an RFID server by an RFID tag according to the present invention, in a method in which an RFID tag performs mutual authentication with an RFID server, the first to third secret keys of the RFID server and Sharing a plurality of secret keys, including a fourth to sixth secret key; Setting a private key retention state and transmitting the request according to a request of an RFID server; Authenticating the RFID server by receiving the server authentication information generated by the RFID server based on a predetermined random number and secret keys; Transmitting, by the RFID server, tag authentication information for authenticating the RFID tag if the server is an authenticated RFID server; And updating, by the RFID server, the secret keys which have been received and maintained by the secret key update information transmitted when the authentication is successful.

In order to achieve the above technical problem, a method of authenticating an RFID tag by an RFID server according to the present invention comprises the steps of: sharing at least one secret key with an RFID tag in a method in which an RFID server performs mutual authentication with an RFID tag; ; Receiving a secret key holding state of the RFID tag and determining the secret keys to apply accordingly; Generating server authentication information generated based on a predetermined random number and a secret key and transmitting the generated server authentication information to the RFID tag; Receiving tag authentication information from the RFID tag and authenticating the RFID tag; And generating successful secret key update information, transmitting the generated secret key update information to the RFID tag, and updating the secret keys.

According to another aspect of the present invention, a method for performing mutual authentication between an RFID tag and an RFID server according to the present invention generates an RFID server and a fourth to sixth secret key for generating an RFID first to third secret key. In a method of mutual authentication between an RFID server and an RFID tag sharing a plurality of secret keys, the RFID tag communicates through a reader, and the RFID tag transmits according to a request of the RFID server after setting its own secret key holding state. Doing; Determining, by an RFID server, secret keys to be applied to the secret key holding state; And transmits server authentication information including first to second parameters generated based on a first random number generated by the RFID server, a first secret key of the secret key, and a second secret key. The tag authenticating the RFID server; If the RFID tag authenticates the RFID server, the second random number extracted from the first parameter of the server authentication information, the third random number generated by the RFID tag, and the fourth to sixth secret keys are generated. Generating the tag authentication information including the fourth to sixth parameters based on the secret key and transmitting the generated tag authentication information to the RFID server; Receiving, by the RFID server, the tag authentication information, and authenticating the RFID tag and updating secret keys held by the RFID server when the authentication is successful, transmitting secret key update information to the RFID tag; And updating the secret keys held by the RFID according to the secret key update information, and updating the secret key holding state.

With reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. 1 is a block diagram showing an RFID authentication network structure to which the present invention is applied. 2 is a flowchart illustrating a process of authenticating an RFID server by an RFID tag according to the present invention, and FIG. 3 is a flowchart illustrating a process of authenticating an RFID tag by an RFID server according to the present invention. 4 is a flowchart illustrating a mutual authentication process between an RFID server and an RFID tag according to the present invention, FIG. 5 is a flowchart showing the operation of the RFID tag of FIG. 2 in more detail, and FIG. 6 is an RFID tag authentication server of FIG. A flowchart showing the operation of the in more detail. Finally, Figure 7 is a command and message format to be added to the EPC GEN2 standard.

Referring to FIG. 1, an RFID authentication network structure, an RFID tag block 110 representing an article, a product, a poster, a card, etc. to which an RFID tag is attached, an RFID reader 120 reading an RFID tag, and an RFID It consists of an RFID authentication server 130 for authenticating the tag (110). Under this network configuration, the present invention is directed to providing authentication services for tags, particularly in untrusted reader environments. That is, the reader 120 may be operated by a normal user or may not be trusted in an environment in which the reader 120 may be operated by an illegal user who collects authentication information, that is, a secret key, and attempts to duplicate a tag. It aims at providing authentication service in environment. In addition, when the RFID tag authentication server 120 shares a secret key used for authentication with a tag, an EPC information service (EPC IS), a mobile application server or a separate authentication server defined by EPCGlobal may serve as the authentication server. Can be.

Referring to FIGS. 2 and 3, a method of authenticating an RFID server by an RFID tag and a method of authenticating an RFID tag by an RFID server will be described in general, and with reference to FIGS. 4 and 5, it will be described in detail. .

First, the operation of the RFID tag will be described. The RFID tag stores a plurality of secret keys including three secret keys (first to third secret keys) generated by the RFID server and three secret keys (four to six secret keys) generated by the RFID server. Share (S210). First, it sets its own secret key holding state, that is, a changed value or a previous value, and transmits it according to the request of the RFID server (S220). At this time, by selecting one field (Authentication-bit) of the message (720 of FIG. 7) that can know whether the secret keys are updated or not, and setting it to a bit value indicating one of updating or maintaining the previous value, the secret key is maintained. Tells. Next, the RFID server receives server authentication information generated based on a predetermined random number and a secret key to authenticate the RFID server (S230 to S240). As a result, if the RFID server is authenticated, the RFID server transmits tag authentication information for authenticating the RFID tag (S250). Finally, the RFID server receives and maintains the secret key update information transmitted when the RFID server succeeds in authentication. The procedure is terminated by updating the secret keys (S260).

Referring now to Figure 3, look at the performance of the RFID server. First, as in the case of the above RFID tag, at least one secret key is shared with the RFID tag. In this case, it is preferable to share six secret keys (S310). Next, a secret key holding state maintained by the tag is received from the RFID tag, and the secret keys to be applied are determined accordingly (S320). At this time, if the RFID tag is normally authenticated, it is decided to apply the updated secret keys, and if it is not normally authenticated, the previous secret keys are applied. In operation S330, server authentication information generated based on a random number and a secret key is generated and transmitted to the RFID tag. Next, the tag authentication information is received from the RFID tag to authenticate the RFID tag (S340). If the RFID tag authentication succeeds because the information is identical, the secret key update information is generated, transmitted to the RFID tag, and the secret keys are updated. End (S350).

Now, with reference to Figures 4 to 6 to look at the process of the RFID tag and the RFID server interworking authentication. Prior to describing a preferred embodiment of the present invention, a secret key, a random number, and an authentication bit are defined in the following description.

-S, S ', S' ', T, T', T '': 6 secret keys shared by RFID tag and RFID certificate server

-S, S ', S' ': Secret key presented to RFID tag by RFID authentication server

-T, T ', T' ': Secret key presented by RFID tag to RFID server

In order to prevent the replay attack, the key transmitted between the RFID tag and the RFID authentication server is EXCLUSIVE-OR with the next random number to transmit and receive the result value.

-R: Random number generated by RFID certificate server

-R ': Random number generated from RFID tag

-R '': Random number generated to check response of RFID authentication server in RFID tag

-authentication bit: a bit indicating the status of the authentication procedure managed by the tag, which indicates that the authentication and secret key update procedures have been completed, or that only the authentication procedure has been performed and the secret key update procedure has not been completed.

In case of the RFID application service that needs to check whether the RFID tag is a legitimate non-replicated tag, the reader 120 reads the code of the RFID tag 110 through an inventory procedure and determines whether the tag is authentic or not. The authentication request is delivered to the RFID authentication server 130. In particular, in the present invention, it is possible to transmit the maintenance state of the secret key to determine whether the secret key to be applied is the previous value or the updated value. That is, the RFID reader 120 transmits the EPC code of the RFID tag, which is the authentication target, to the RFID authentication server 130 and requests authentication of the tag (S410). The RFID authentication server 130 first queries the RFID tag 110 with status information of the RFID tag 110. The reader 120 relays the status information request message of the RFID authentication server 130 to the tags (S420 to S430). The RFID authentication server 130 generates a random number and transmits a result value obtained by performing an exclusive OR operation with the secret key to the RFID tag 110 via the reader 120 (S440). The RFID tag 110 compares the secret key sent by the RFID authentication server 130 with the secret key stored therein to confirm whether the authentication process is started from a legitimate authentication server. Create and send the result of XOR operation of the secret key to present to the RFID authentication server (130) (S450). The RFID authentication server 130 checks whether the secret key sent by the RFID tag 110 and the secret key managed by the RFID tag 110 are the same, and determines whether the RFID tag is legal or authentic. In addition, when authentication is completed, the RFID tag 110 and the RFID authentication server 130 renews the secret key to a new secret key using the existing secret key and random number (S460). According to the authentication mechanism defined in the present invention, even if an untrusted illegal leader exists, the authentication mechanism can be restored without being compromised. Secrets are used in a one-time-password fashion to prevent malicious readers from inferring the secret key.

Now, the RFID authentication server 130 generates a random number R and XORs the secret keys S and S (S ⓧ R, S ⓧ R) to the RFID tag 110 and receives it (S510). ) Confirms that the server is authorized by checking the secret keys S1 and S2 sent by the RFID authentication server 130 in the following manner.

Step 1. From the first parameter S ⓧ R of the message sent from the RFID authentication server 130, the RFID tag 110 performs the following.

(S ⓧ R) ⓧ S-> R: If S sent by the RFID authentication server 130 and S being stored in the RFID tag 110 are the same, the RFID tag 110 is R sent by the RFID authentication server 130. It is extracted (S513).

Step 2. From the second parameter S 'ⓧ R of the message sent from the RFID authentication server 130, the RFID tag 110 performs the following.

(S 'ⓧ R) ⓧ R-> S': If R extracted by the RFID tag 110 and R generated by the RFID authentication server 130 are the same at step S440, the tag normally restores S 'sent by the server. It may be (S513).

Step 3. It is determined whether S 'sent from the RFID authentication server 130 and S' stored in the RFID tag 110 are the same (S515). As a result of the determination, the RFID tag 110 confirms that the RFID authentication server 130 is an authorized node and performs step S450 of FIG. 4.

If it is not the same, the RFID tag 110 does not respond and ends the procedure.

Next, the RFID tag 110 generates a random number R ', R' ', and generates a secret key T, T', T '' and an exclusive-OR (T ⓧ R ', T' ⓧ R 'ⓧ R, T'). 'Ⓧ R') is sent to the RFDI authentication server 130 (S517), and the tag maintains a new bit (A bit) indicating the authentication status in an unclear state (S519). Next, when the authentication for the RFID tag 110 is successful, the RFID authentication server 130 transmits the random number R '' transmitted by the RFID authentication server `` S '' and Exclusive-OR (S '' 한). R '') is received (S521), and if the transmitted R '' and the received R '' are identical, and if they are the same, the secret keys (S, S ', S' ', T, T', T '') is updated (S523 to S527).

Meanwhile, the RFID authentication server 130 authenticates the RFID tag 110 by checking the secret keys T and T 'in the following manner. First, after receiving the EPC from the reader 120 (S610), and requests the state of the RFID tag 110 (S613), and receives a response corresponding thereto (S615). The A bit, which is the value, is checked (S617), and if it is 0, the old secret key is deleted and the new secret key is applied (S619). If it is 1, the old secret key is deleted and the new secret key is applied. It determines (S621). In addition, S ⓧ R and S ′ ⓧ R are transmitted to the RFID tag 110 (S623). Where S ⓧ R and S 'ⓧ R' are the same as described above. Then, T) R ', T' ⓧ R 'ⓧ R, T' 'ⓧ R' are received from the RFID tag 110 (S625). Again, T ⓧ R ', T' ⓧ R 'ⓧ R, T' 'ⓧ R' are the same as described above. Now, if the secret key to be applied is determined, authenticate as follows.

Step 1. From the first parameter T ⓧ R 'of the message sent from the RFID tag 110, the RFID authentication server 130 performs the following.

     (T ⓧ R ') ⓧ T-> R': If the T sent by the RFID tag 110 and the T stored in the RFID authentication server 130 are the same, the RFID authentication server 130 determines that the RFID tag 110 is the same. The sent R 'is extracted (S627).

Step 2. From the second parameter (T 'ⓧ R' ⓧ R) of the message sent from the RFID tag 110, the RFID authentication server 130 performs the following.

(T 'ⓧ R' ⓧ R) ⓧ R 'ⓧ R-> T': If R 'extracted by the RFID authentication server 130 in step 1 of S450 and R' generated by the RFID tag 110 are the same, If R sent by the RFID tag 110 and R generated by the RFID authentication server 130 are the same, the RFID authentication server 130 may restore T 'sent by the RFID tag 110 normally (S627).

Step 3. It is determined whether T 'sent from the RFID tag 110 and T' stored by the RFID authentication server 130 are the same (S629).

If the same, the RFID authentication server 130 confirms that the tag is a normal tag, and sends the received random number R '' and S '' and Exclusive-OR (S '' ⓧ R '') to the tag (S631). On the basis, the RFID tag 110 checks whether the transmitted R '' and the received R '' are the same, and if it is the same, the secret keys S, S ', S' ', T, T' are identical to the RFID authentication server 130. , T ''). The RFID authentication server also updates and holds the secret key (S633).

If authentication fails, the RFID authentication server 130 returns the result to the reader 120 and terminates the procedure.

However, when the reader 120 is a trusted legitimate leader, authentication is completed according to the authentication procedure, and the secret key will also be normally updated. However, if the reader is a malicious reader and the malicious reader does not transmit the message sent by the RFID authentication server 130 to the RFID tag in S460 of FIG. 4, the RFID tag does not renew the secret key. As a result, since the secret key stored in the RFID tag and the RFID authentication server is different, the authentication will fail even though the RFID tag and the RFID authentication server are legitimate in the next authentication procedure.

In order to solve this problem in the present invention, the RFID authentication server is a new secret key (S _i , S ' _i , S'' _i , T _i , T' _i , T '' _i ) and a new one to be used in the next authentication procedure. The private keys (S _{i + 1} , S ' _{i + 1} , S'' _{i + 1} , T _{i + 1} , T' _{i + 1} , T '' _{i + 1} ) are stored together, and the RFID tag Introducing a new bit (A-bit) to receive the Ack message (S''ⓧR '') from the RFID authentication server as shown in S460 of Figure 4, clears the A-bit ("0"), if If an Ack message (S '' \ R '') is not received, the RFID tag keeps the A-bit unclear ("1").

Before performing the authentication procedure, the RFID authentication server queries the RFID tag for the A-bit value, and if it is determined that the A-bit secret key has not been renewed, the RFID authentication server determines that the previous authentication session has not been completed normally. It works in conjunction with a trusted dedicated device (reader) to authenticate the RFID tag and renew the key. At this time, since the RFID tag is storing the old secret keys (S _i , S ' _i , S'' _i , T _i , T' _i , T '' _i ), the RFID authentication server uses a new secret key (S _{i + 1).} , S ' _{i + 1} , S'' _{i + 1} , T _{i + 1} , T' _{i + 1} , T '' _{i + 1} ) and delete the previous secret key (S _i , S ' _i , S'' _i , T _i , T ' _i , T'' _i ).

In the interval between the RFID tag and the RFID authentication server, in order to conceal the secret key delivered for authentication, the random number and the exclusive-OR operation were used and the values were transmitted and received over the network and the RF radio section. However, it is possible for an attack leader to infer a secret key from numerous messages obtained by repeatedly performing normal authentication. Therefore, the private key is used only once by one-time password method, and it is designed to use the updated private key in the next authentication procedure. Here's how to create a new key:

는 one-linear 함수이고, here,

Is a one-linear function,

:0과1로 구성된ℓ길이의 비트열이다.

: Is a bit-length string of lengths 0 and 1.

(R,R'_i) S _{i + 1} <-S _i ⓧ

(R, R ' _i )

(R'_i,R''_i)S ' _{i + 1} <-S' _i ⓧ

(R ' _i , R'' _i )

(R''_i,R)S '' _{i + 1} <-S '' _i ⓧ

(R '' _i , R)

(R''_i,R)T _{i + 1} <-T _i ⓧ

(R '' _i , R)

(R'_i,R''_i)T ' _{i + 1} <-T' _i ⓧ

(R ' _i , R'' _i )

(R,R'_i)T '' _{i + 1} <-T '' _i ⓧ

(R, R ' _i )

7 illustrates a command to be used in an RFID radio section between an RFID tag and a reader. If the present invention is applied to the EPC Gen2 to be used as the industry standard of the 900MHz frequency band, it is necessary to further define the commands not defined in the EPC Gen2 standard while complying with the EPC Gen2 standard. 710 and 720 of FIG. 7 are query message and response message formats for a command for querying state information storing a state of a previous authentication procedure of an RFID tag, and 730 and 750 indicate a secret key between an RFID tag and an RFID authentication server. Message format, and 760 and 770 are acknowledgment message for key update and its response message format. If the present invention is applied to the EPC Gen2 standard, the secret key is stored in the EPC Reserved memory bank area where the Kill / Access password is stored.

The invention can also be embodied as computer readable code on a computer readable recording medium. Computer-readable recording media include all kinds of recording devices that store data that can be read by a computer system.

Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, which are also implemented in the form of carrier waves (for example, transmission over the Internet). It also includes. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims.

Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the mutual authentication method of the RFID tag and the RFID server according to the present invention can be implemented by using only a relatively short secret key and exclusive-OR operation function, and thus can be applied to a passive RFID tag that does not have its own power source, thereby making it inexpensive. It is possible to spread to various RFID fields that require authentication function by making low tag.

The present invention has the effect of providing a variety of application services that require tag authentication by verifying the legitimacy of the tag by verifying the secret key between the RFID tag sharing the secret key and the RFID tag authentication server.

In addition, when the authentication process through mutual verification of the secret key is completed, the present invention updates the secret key used for authentication to a new value. Thus, even if a secret key is leaked by an attack of an unreliable RFID reader, a tag copy protection can be obtained through the secret key update method according to the present invention.

Claims (19)

In a method in which an RFID tag performs mutual authentication with an RFID server, (a) sharing a plurality of secret keys including a first to third secret key of the RFID server and a fourth to sixth secret key thereof; (b) setting the private key holding state and transmitting it according to a request of the RFID server; (c) receiving, by the RFID server, server authentication information generated based on a predetermined random number and secret keys to authenticate the RFID server; (d) if the RFID server is an authenticated RFID server, transmitting tag authentication information for authenticating the RFID tag; And (e) updating the secret keys that have been received and maintained by the RFID server when the authentication is successful and the secret key update information transmitted by the RFID server, wherein the RFID tag performs mutual authentication with the RFID server. . The method of claim 1, wherein step (b) An RFID tag may be configured to select a field of a message transmitted / received between the RFID server and the RFID tag to determine whether the secret keys are updated, and to set a value indicating one of updating or maintaining a previous value. How to perform authentication. The method of claim 1, wherein step (c) (c1) receiving the server authentication information including first to second parameters generated based on a first random number generated by the RFID server, a first secret key of the secret key, and a second secret key; And verifying whether the RFID tag is an authenticated RFID server. The method of claim 3, wherein step (c1) (c11) extracting a random number by performing an exclusive OR on the first parameter with a first secret key; (c12) determining whether the extracted secret key is the same as the second secret key by performing an exclusive OR of the random number extracted in the step (c11) and the second parameter; And (c13) if not equal, determine as an unauthorized RFID server, and if same, determine as an authenticated RFID server; wherein the RFID tag performs mutual authentication with the RFID server. The method of claim 1, wherein step (d) (d1) In the case of the authenticated RFID server, the fourth to the fifth based on the second random number extracted from the first parameter of the server authentication information, the third random number generated by itself, and the fourth to sixth secret keys of the secret key. And generating the tag authentication information including the six parameters and transmitting the generated tag authentication information to the RFID server. The method of claim 5, wherein step (d1) (d11) generating a fourth parameter by performing an exclusive OR on the fourth secret key and the second random number; (d12) generating a fifth parameter by performing an exclusive OR on the fifth secret key, the second random number, and the third random number; And (d13) generating a sixth parameter by performing an exclusive logical OR of the sixth secret key and the fourth random number to generate the fourth to sixth parameters as tag authentication information; How to perform mutual authentication with an RFID server. The method of claim 1, wherein step (e) (e1) receiving the secret key update information having a result of an exclusive OR of a third secret key and a fourth random number; And (e2) if the random number extracted from the secret key update information is the same as the fourth random number, updating the first to sixth secret keys; wherein the RFID tag performs mutual authentication with the RFID server. Way. The method of claim 1 or 7, wherein step (e) If the authentication is successful, an exclusive logical sum of the secret key including the stored first to sixth secret keys, the generated value using the random numbers as the input of the first nonlinear function, and the corresponding first to sixth secret keys, respectively, is determined. And the first to sixth secret keys are updated to perform mutual authentication with the RFID server. In the RFID server to perform mutual authentication with the RFID tag, (a) sharing at least one secret key with an RFID tag; (b) receiving a secret key holding state of the RFID tag and determining the secret keys to apply accordingly; (c) generating server authentication information generated based on a predetermined random number and secret keys and transmitting the generated server authentication information to the RFID tag; (d) authenticating the RFID tag by receiving tag authentication information from the RFID tag; And (e) generating a secret key update information and transmitting the generated secret key update information to the RFID tag and updating the secret keys if the authentication is successful, wherein the RFID server performs mutual authentication with the RFID tag. The method of claim 9, wherein step (b) And if the RFID tag is normally authenticated, apply the updated secret keys, and if it is not normally authenticated, determine to apply previous secret keys. The method of claim 9, wherein step (c) Generate and transmit the server authentication information including a first parameter that results from the exclusive OR of the first random number and the first secret key, and a second parameter that results from the exclusive OR of the first random number and the second secret key. And mutual authentication with the RFID tag by the RFID server. The method of claim 9, wherein step (d) (d1) a fourth parameter having an exclusive logical sum of the fourth random number and the second random number generated by the RFID tag; a fifth parameter having an exclusive logical sum of the fifth secret key and the second random number and the first random number; Receiving tag authentication information including a sixth parameter having an exclusive logical sum of the third random number generated by the key and the RFID tag; (d2) extracting the second random number by performing an exclusive logical OR between the fourth parameter and the fourth secret key held by the RFID server; (d3) extracting a fifth secret key by performing an exclusive logical OR on the fifth parameter, the second random number extracted in the step (d2), and the first random number generated by the RFID server; (d4) The third random number is successfully extracted by performing an exclusive logical OR of the sixth parameter and the sixth secret key held by the RFID server, and finally the sixth secret key extracted from the tag authentication information is the RFID server. If the authentication is the same as the sixth secret key to maintain the authentication; RFID server comprising a method for performing mutual authentication with the RFID tag. The method of claim 9, wherein step (e) (e1) generating the secret key update information by performing an exclusive logical OR on the third random number extracted from the server authentication information; (e2) by performing an exclusive OR of the secret key including the stored first to sixth secret keys, the generated value using the random numbers as the input of the first nonlinear function, and the corresponding first to sixth secret keys, respectively. And the RFID server performs mutual authentication with the RFID tag, wherein the first to sixth secret keys are updated. In the RFID server for generating the first to third secret key and the RFID tag for generating the fourth to sixth secret key communicates through a reader, and the mutual authentication method of the RFID server and the RFID tag sharing the secret keys, (a) transmitting the RFID tag according to a request of the RFID server after setting its secret key holding state; (b) determining, by the RFID server, secret keys to be applied to the secret key holding state; (c) transmitting server authentication information including first to second parameters generated based on a first random number generated by the RFID server, a first secret key of the secret key, and a second secret key, respectively; Accordingly, the RFID tag authenticating the RFID server; (d) If the authentication of step (c) succeeds, the second random number extracted from the first parameter of the server authentication information, the third random number generated by the RFID tag, and the fourth to sixth secret keys of the secret key. Generating the tag authentication information including the fourth to sixth parameters, respectively, and transmitting the generated tag authentication information to the RFID server; (e) the RFID server receiving the tag authentication information, authenticating the RFID tag accordingly, and updating the secret keys held by the RFID server while transmitting the secret key update information to the RFID tag upon successful authentication. ; And (f) updating the secret keys held by the RFID according to the secret key update information, and updating the secret key holding state. The method of claim 14, wherein step (b) And if the RFID tag is normally authenticated, apply the updated secret keys, and if not, determine to apply previous secret keys. The method of claim 14, wherein step (c) (c1) extracting a random number by performing an exclusive logical OR of the first parameter generated based on the first random number generated by the RFID server and the first secret key generated by the RFID server; (c2) a RFID in which the secret key extracted by exclusively ORing the random number extracted in the step (c1), the second parameter generated based on the first random number generated by the RFID server and the second secret key is maintained by the RFID; Determining whether it is the same as 2 a secret key; And (c3) if not the same, determine as an unauthorized RFID server, and if the same as an authenticated RFID server; mutual authentication method of the RFID server and the RFID tag comprising a. The method of claim 14, wherein step (e) (e1) extracting a second random number by performing an exclusive logical OR between the fourth parameter and the fourth secret key held by the RFID server; (e2) extracting a fifth secret key by performing an exclusive logical OR on the fifth parameter, the second random number extracted in the step (e1), and the first random number generated by the RFID server; And (e3) The third random number is successfully extracted by performing an exclusive logical OR of the sixth parameter and the sixth secret key held by the RFID server, and finally the sixth secret key extracted from the tag authentication information is the RFID server. If it is equal to the sixth secret key held by the user, making the authentication successful; And and (e4) generating the secret key renewal information by performing an exclusive logical OR of the third random number extracted from the server authentication information and the third secret key. The method of claim 14, Updating the secret key may include generating the secret key including the stored first to sixth secret keys, a generated value for inputting the random numbers as a primary nonlinear function, and corresponding first to sixth secret keys, respectively. And performing an exclusive logical OR to replace the first to sixth secret keys to perform mutual authentication of the RFID server and the RFID tag. 15. A recording medium readable by a cup computer that records a program that can execute the mutual authentication method of any one of claims 1, 9, or 14 on a computer.

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