KR20100111998A - Method for encryption communication in radio frequency identification - Google Patents

Abstract

PURPOSE: A communication encryption method in an RFID system for increasing the protection of personal information without the influence about a passive type tag and a reader communication method is provided to protect personal information by encrypting a response to the tag from the reader. CONSTITUTION: A reader(20) transmits a command for the encryption to a tag(10). The tag generates 16 bit pseudo random number. The reader encrypts the 16 bit pseudo random number according to the priority. The tag compares the pseudo random number with the decoded pseudo random number after decoding the encrypted pseudo random number. The tag transmits ACK signal to the reader.

Description

Method for encryption communication in radio frequency identification}

The present invention relates to a communication encryption method in an RFID system that protects information by encrypting a response of a tag from an unauthenticated reader in an RFID system that performs communication between a reader and a tag.

Radio frequency identification (RFID) technology is recognized as a core technology that enables optimal operation of supply chain management (SCM) among existing technologies. Through RFID technology, administrators can create and process all information related to identification of objects, location movement tracking, and history management to be obtained from the SCM network. In addition, RFID technology is one of the closest technologies that can realize the ubiquitous network world among various technologies, and its importance is increasing.

UHF band RFID technology can recognize tags even at a distance of about 8.4 meters in a wireless environment.

On the other hand, the tag contains unique identification number (UID) information. The tag is attached to each object to store the UID of the object, and the reader can not only identify the UID information of the tag but also record additional information in the internal storage space of the tag and read the recorded additional information.

In the communication between the reader and the tag, various communication standards exist in data coding, modulation, anti-collision, data demodulation and demodulation, but at present, electronic product code (EPC) class1 generation2 (C1 Gen2). The standard is registered in ISO / IEC and is widely used internationally.

1 is a block diagram showing the internal configuration of a passive RFID tag (hereinafter referred to as a 'tag') according to the prior art.

Referring to FIG. 1, the passive tag 10 includes an antenna 1, a demodulator 2, a decoder 3, a controller 4, a memory 5, an encoder 6, a modulator 7, and a clock generator. 8 and the voltage supply part 9 can be provided.

The antenna 1 is a part that receives a signal such as a command or data from a reader located outside. The antenna 1 receives the modulated signal to generate a high frequency alternating current or alternating voltage.

The demodulator 2 demodulates a modulated signal such as the command or data and restores the original signal. The demodulation may be to remove the combined carrier from the received signal upon modulation.

The decoder 3 decodes the signal for the command or data recovered in the demodulator 2.

The controller 4 receives the result of decoding the signal from the decoder 4 and controls each part inside the tag 10 to execute a command corresponding to the signal according to the result. The controller 4 may record the received data in the memory 5 to be described later, and read data stored in the memory 5.

The memory 5 stores various kinds of passwords (access passwords, kill passwords, etc.), various information about the article to which the tag 10 is attached, and the like.

The encoder 6 encodes the data read out from the memory 5 or the control signal generated by the controller 4. The hatched control signal may be a command for requesting an external reader to perform a specific operation.

The modulator 7 modulates the encoded data or control signal and provides it to the antenna 1.

The clock generator 8 generates a clock signal of a constant frequency and applies a clock signal to the controller 4 so that the controller 4 operates in synchronization with the clock signal.

The voltage supply unit 9 generates power from a signal received from the reader, and supplies power for operation of each part. The voltage supply unit 9 converts the AC voltage generated by the antenna 1 into a DC voltage and supplies the same to each part inside the tag 1.

Such a tag is pointed out as a problem of ease of leakage of personal information by expanding the base of RFID technology and the possibility of privacy invasion by commercialization of personal information. In other words, the information stored in the tag is very vulnerable to security because there is no restriction on the reader's access to the tag's internal information. Therefore, it is necessary to use a technique to protect the information stored in the tag. However, the conventional passive tag has a problem that it is difficult to use the existing information protection technique because of the limited capacity of the memory.

Technical problem to be solved by the present invention by changing the encryption generation criteria of the pseudo-random number generated in the tag from time to time to communicate between the reader and the tag, RFID to encrypt the response of the tag from the unauthorized reader to protect personal information The present invention provides a method for encrypting communication in a system.

Communication encryption method in the RFID system for solving the technical problem to be achieved by the present invention is an operating method of the RFID system that the reader and the tag performs the communication, (a) any of the reader transmits the encryption command to the tag step; (b) the tag generating a pseudo random number and transmitting the pseudo random number to the reader; (c) the reader encrypting the pseudo random number and transmitting the encrypted random number to the tag; And (d) comparing the encrypted pseudo random number received by the tag and the pseudo random number stored therein to perform the reader authentication.

In the present invention, in step (b), the reader may reorder by applying the priority set to the received pseudo random number and transmit the rearrangement to the tag.

In the present invention, in step (d), the tag may decode the encrypted pseudo random number according to the set priority, and compare the decoded pseudo random number with a pseudo random number stored therein.

In the present invention, in step (d), if the encrypted pseudorandom number and the pseudorandom number stored therein match, a confirmation signal is transmitted to the reader, otherwise, the reader may not respond.

In the present invention, the method may be performed in an access process in which the reader performs a read / write operation on the tag memory.

In the present invention, the method may be performed in an inventory process in which the reader recognizes the tag.

As described above, according to the present invention, the encryption method due to insufficient memory capacity of the existing passive tag is improved, thereby creating an effect of strengthening personal information without affecting the passive tag and reader communication method.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

2 is an RFID system diagram illustrating data communication between an authenticated reader and an unauthenticated reader and a tag. According to FIG. 2, the RFID system includes a reader 20 (including an antenna connected to the reader 20 to transmit radio waves to a tag), a tag 10 for storing information and exchanging data with the reader 10, The reader 20 includes a first reader 21 as an authenticated reader and a second reader 22 and a second reader 23 as an unauthenticated reader.

In the RFID system, the data communication method between the reader 20 and the tag 10 is composed of three processes, namely, a select process, an inventory process, and an access process. The select process is a process of selecting a tag group corresponding to a condition desired by a user, and a select command exists. The inventory process is to recognize the tags 10 of the selected tag 10 group. The inventory process selects one of the four sessions existing in the tag 10, and the reader 20 sends a Query command to the inventory round. Begins. One or more tags 10 may be responded to by sending the Query command of the reader 20. The inventory process includes various commands such as Query, QueryAdjust, QureyRep, ACK, NAK, and so on. In the inventory process, tag 10 generates two 16-bit pseudo-random numbers. The access process is an operation of reading data from or writing data to the memory of the tag 10, and the tag 10 must be uniquely identified before the access. The access process includes various commands such as Req_RN, Read, Write, Kill, Lock, and so on.

In the present invention, to protect personal information by encrypting the tag 10 response from the reader (the second reader 22 and the third reader 23) that is not authenticated in the communication between the reader 20 and the tag 10.

As shown in FIG. 1, the passive tag 10 does not have its own power supply and should be designed to minimize power and area as much as possible in the encryption process. And if the encryption format is fixed, it can identify the data format encrypted by malicious. Considering these points and designing using the existing communication method to the maximum, the area can be minimized and encryption can be achieved. The encryption generation criterion selects a 16-bit pseudo random number from the tag response of the conventional communication method, and changes the encryption data format from time to time by changing the encryption generation criteria from time to time using this pseudo random number. The design also compares only 16-bit data sizes to minimize power usage. Encryption generation criteria may be more complicated, and the encryption process may be more complicated, but it does not meet the low power and minimal aspects that are the basic characteristics of the tag 10. If the power consumption increases, the communication distance between the tag 10 and the reader 20 may be shortened. And since tag 10 has a minimum response time for commands from reader 20, this should also be considered.

3 is a flowchart illustrating the operation of a communication encryption method in an RFID system according to the present invention.

The reader 20 transmits an encryption command to the tag 10 (step 301).

The tag 10 receiving the encryption command from the reader 20 generates a 16-bit pseudo random number (step 302), and transmits the generated pseudo random number to the reader 20 (step 305).

The reader 20 which receives the 16-bit pseudorandom number from the tag 10 encrypts it according to the priority (step 307) and transmits it to the tag 10 (step 309).

16-bit pseudo-random encryption divides pseudorandom numbers into regular blocks, arranges them in a matrix, and transfers them in columns and rows. However, when processing data through encryption, a memory having a capacity for temporarily storing data is required, which is a signal generation concern. However, the tag 10 response may solve the problem of signal delay by changing a memory address when determining response data by reading and responding to a memory value.

4 is a diagram for explaining the priority determination when the reader 20 encrypts 16-bit pseudo-random numbers. Receiving the 16-bit pseudo-random number, the reader 20 may determine the priority through the process of step 1 to step 4 as shown in FIG. In the first step, it is assumed that many days have higher priority by comparing the upper 8 bits and the lower 8 bits. If the number of 1s is the same, the priority is given the lower bit. In step 2, the 8 bits performed in step 1 are further divided by 4 bits to proceed as in step 1 to determine priority. In step 3, the 4 bits performed in step 2 are divided by 2 bits, and the priority is determined by the same operation as in step 1. In step 4, the 2 bits performed in step 3 are divided by 1 bit and the same as in step 1. Work to determine final priority.

When the final priority is determined, the reader 20 starts transmitting data from the higher priority, and the tag 10 decodes the data from the higher priority. That is, in FIG. 4, the data priority is the 15th bit → 14th bit → 12th bit → 13th bit → 10th bit → 11th bit → 9th bit → 8th bit → 1st bit in step 4, which is the last step. → 0th bit → 3rd bit → 2nd bit → 7th bit → 6th bit → 5th bit → 4th bit The data is transmitted in order. As shown in the example shown in FIG. 4, the 16-bit pseudo random number received from the tag 10 is divided into specific blocks to prioritize them (regardless of the size of the blocks), and various types of rows and columns are defined and used. Can be.

Upon receiving the encrypted pseudo random number, the tag 10 decodes it and compares the decoded pseudo random number with the pseudo random number previously transmitted to the reader 20 to determine whether it is the same (step 311).

As a result of the comparison, if the decoded pseudorandom number and the pseudorandom number previously transmitted to the reader 20 are the same, the previous 16-bit pseudorandom number is transmitted while transmitting an acknowledgment (ACK) signal to the reader 20, and the decoded pseudorandom number and the previous If the pseudo random number transmitted to the reader 20 is not the same, a request for retransmission of the encrypted data is not requested or a response signal is not transmitted (step 313). For example, in the case of the first reader 21, the decoded pseudorandom number and the pseudorandom number previously transmitted to the reader 20 are the same to be authenticated, and the second reader 22 and the third reader 23 are authenticated. Since the decoded pseudo random number and the pseudo random number previously transmitted to the reader 20 are not the same, authentication is not performed.

 5 and 6 illustrate changes in the state of the tag 10 for viewing data from an unauthorized reader 20.

FIG. 5 illustrates a method in which an unauthenticated reader 20 cannot read or write a specific memory area of the tag 10. When the response signal of the tag 10 after the open state in the tag uses data generated through encryption. to be.

In FIG. 5, when the tag 10 detects a signal from the reader 20, the tag 10 wakes up from a sleep state and determines whether the tag 10 is in the Kill state. If the tag 10 is not in the Kill state, the tag 10 transitions the state to the Ready state after initializing the internal setting.

The reader 20 transmits an inventory command to the tag 10 in the ready state, and the tag 10 receiving the inventory command transitions its state to a reply state when the slot value is 0. On the other hand, if the slot value is not 0, it waits for the QueryAdjust and QueryReq commands and then transitions to the Reply state when the slot value becomes 0. The inventory command may include Query, QueryAdjust, QueryRep.

Meanwhile, the tag 10 transmits a 16-bit pseudo random number to the reader 20 in response to the inventory command from the reader 20.

Then, when the reader 20 transmits an ACK value to the tag 10, the tag 10 transmits a protocol control (PC), a unique item identifier (UII), and a CRC-16 to the reader 20 and transitions to the acknowledgment state. do. In addition, the reader 20 transmits a signal requesting to transmit the pseudo random number to the tag 10 again, and the reader 20 responds with a handle value and transitions to the open state.

In the open state, the reader 20 may perform a read and write function with respect to the memory of the tag. Thereafter, the reader 20 transmits an encryption command to the tag 10 for data protection, and the tag 10 transmits a 16-bit pseudorandom number to the reader 20. The reader 20 encrypts the pseudo random number in order of priority and transmits it to the tag 10. The tag decodes the encrypted pseudo random number and transmits an ACK signal to the reader 20 when the pseudo random number is the same as the previously sent pseudo random number. Otherwise, no response signal is transmitted.

6 is to prevent the unauthorized reader 20 from reading or using the data for all areas of the tag 10 by using the data generated through encryption of the response signal of the tag 10 after the Reply State. In FIG. 6, the method of FIG. 3 is applied to the tag 10 that is transitioned to the Reply state. The reader 20 sends an encryption command to the tag 10 in the Reply state, and the tag 10 transmits a 16-bit pseudorandom number to the reader 20. The reader 20 encrypts the pseudo random number in order of priority and transmits it to the tag 10. The tag decodes the encrypted pseudo random number and transmits an ACK signal to the reader 20 when the pseudo random number is the same as the previously sent pseudo random number. Otherwise, no response signal is transmitted.

The difference between FIG. 5 and FIG. 6 is whether to encrypt and transmit a specific area in the tag 10 or to encrypt and transmit data in all memory areas of the tag 10. Determining the memory area to be protected in FIGS. 5 and 6 may be defined in the encryption command in step 301. After the instruction, the required number of bits is allocated to determine the memory area to be protected.

The above detailed description and drawings are merely exemplary of the present invention, but are used only for the purpose of illustrating the present invention and are not intended to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical protection scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a block diagram showing the internal configuration of a passive RFID tag according to the prior art.

2 is an RFID system diagram illustrating data communication between an authenticated reader and an unauthenticated reader and a tag.

3 is a flowchart illustrating the operation of a communication encryption method in an RFID system according to the present invention.

FIG. 4 is a diagram for describing priority determination at the time of encryption according to FIG. 3.

5 is a view showing a state change of the RFID tag according to the first embodiment of the present invention.

6 is a view showing a state change of the RFID tag according to the second embodiment of the present invention.

Claims (6)

An operating method of an RFID system in which a reader and a tag communicate with each other, (a) any reader sending an encryption command to the tag; (b) the tag generating a pseudo random number and transmitting the pseudo random number to the reader; (c) the reader encrypting the pseudo random number and transmitting the encrypted random number to the tag; And (d) comparing the encrypted pseudo random number received by the tag with the pseudo random number stored therein and performing the reader authentication. The method of claim 1, wherein in step (b) And the reader reorders the priorities set to the received pseudo random numbers and transmits them to the tag. The method of claim 2, wherein in step (d) And the tag decodes the encrypted pseudorandom number according to the set priority, and compares the decoded pseudorandom number and the pseudorandom number stored therein. The method of claim 3, wherein in step (d) And transmitting an acknowledgment signal to the reader when the encrypted pseudorandom number and the pseudorandom number stored therein are matched, and otherwise responding to the reader. The method of claim 4, wherein the method And the reader performs an access process of performing a read / write operation on the tag memory. The method of claim 4, wherein the method Communication encryption method characterized in that the reader is performed in the inventory process to recognize the tag.

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