CN106203579A - A kind of safe RFID label tag random number automatic update method - Google Patents

Abstract

The RFID authentication method must have the ability to resist tracking attacks. It cannot be realized only by simple key update, but also needs to generate random numbers in the tag, and add the random numbers to the calculation of the information transmitted during the authentication process. However, the random number generator will increase the design complexity and cost of the label. Therefore, designing a random number automatic update method has important research significance and use value. The present invention proposes a safe method for automatically updating random numbers of RFID tags to replace traditional random number generators, and adds random numbers to the calculation of transmission information in the authentication process to ensure that the feedback information of RFID tags in each authentication is accurate. The same, so as to play the role of tag anti-tracking. The random number automatic update method is based on the original encryption algorithm in the tag, such as HASH, MIXBITS, Rabin and so on. The method solves the problem of high label production cost in the current RFID system, and simultaneously improves the security and authentication efficiency of RFID authentication.

Description

A Safe Automatic Update Method of RFID Tag Random Number

technical field

The invention relates to the field of radio frequency identification research, in particular to a method for automatically updating tag random numbers in a safe RFID system, wherein the random numbers are used for the calculation of transmission information in the RFID authentication process.

Background technique

Radio Frequency Identification (RFID) is a technology that uses radio frequency signals to achieve contactless information transmission, and uses the transmitted information to achieve authentication and identification purposes. With the popularization of RFID, the specifications, cost and performance requirements of RFID tags are getting higher and higher. Small size, low cost, high performance and high security are called standards for measuring the quality of RFID systems.

An RFID system usually includes three parts: a back-end server system, an RFID reader, and an RFID tag. Due to the limited processing power of the tag and the fact that it is difficult for people to perceive the illegal reading of the radio frequency signal, the communication between the RFID reader and the RFID tag has security and privacy risks, and is vulnerable to various security attacks. In order to resist tracking attacks, Godor G et al. proposed an authentication scheme for updating tag information, but the scheme cannot resist desynchronization attacks. The attacker can make the key between the reader and the tag inconsistent by replaying the message. Thereby destroying the subsequent authentication between the two (Godor G, Imre S. Hash-based mutual authentication protocol for low-cost RFID systems [C]//Proc of the 18th EUNICE Conf on Information and Communications Technologies. Berlin: Springer, 2012: 76 -87.); Zhou et al. proposed a security authentication protocol based on Physically Unclonable Function (PUF), and added a random number generator to the tag to ensure the freshness of the tag feedback information, thus resisting tracking attacks capabilities, but the addition of random number generators greatly increases the cost of tags (Zhou Enhui, Liu Yana.Physically unclonable function based high performance privacy protection algorithm of RFID network[J].Application of Electronic Technique,2016,42(3):98 -101.); Shen et al. proposed a secure RFID authentication protocol based on the nonlinear function MIXBITS, which also added a random number generator to the label to ensure the non-uniqueness of the label feedback information and play a role in resisting tracking, but the same The problem is that adding a random number generator to the tag brings a lot of pressure on the cost of the tag (Shen Jinwei, Ling Jie. An improved ultra-lightweight RFID authentication protocol [J]. Computer Applications and Software, 2015, 32 (2): 304-306.); MA et al. proposed a RFID two-way authentication method based on the Rabin encryption algorithm, which ensures the freshness of the tag feedback information by updating the secret key information, but is still vulnerable to tracking attacks and desynchronization attacks (MA Yuanjia ,LIU Daowei.Improved mutual authentication with backward security for RFIDprotocols[J].Com Puter Engineering and Applications, 2016, 3, 2: 1-5.). Based on the above description, it can be seen that the RFID authentication method must have the ability to resist tracking attacks, and it cannot be realized only by simple key update, but also needs to generate random numbers in the label, and add the random numbers to the calculation of the information transmitted during the authentication process. . However, the random number generator will increase the design complexity and cost of the label. Therefore, designing a random number automatic update method has important research significance and use value.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, propose a safe RFID tag random number automatic update method to replace the traditional random number generator, and add the random number to the calculation of the transmission information in the authentication process to ensure RFID The feedback information of the label in each authentication is different, so as to play the role of anti-tracking of the label. The random number automatic update method is based on the original encryption algorithm in the tag, such as HASH, MIXBITS, Rabin and so on. The method solves the problem of high label production cost in the current RFID system, and simultaneously improves the security and authentication efficiency of RFID authentication.

A safe RFID tag random number automatic update method is included in the following steps:

(1) After the reader authenticates the tag, a random number is generated and stored in the tag;

(2) The tag saves the random number sent by the reader, and sets the parameter tK to 1 to indicate a legal update;

(3) The reader sends a request to the tag;

(4) When the tag receives the reader-writer request, it judges the parameter tK, if tK=1, enters step (6), if tK=0, enters step (5);

(5) Use an encryption algorithm to encrypt the random number to play an update role, and set tK to 0 at the same time;

(6) Apply the random number to the authentication process, and perform follow-up actions.

The reader has the ability to generate random numbers, and the tag has the ability to store random numbers and modify the parameter tK.

After the reader-writer sends a request to the tag in the read-write area, the tag will judge the value of the parameter tK and be able to perform encryption algorithm operations.

The tag can choose the required encrypted content when performing the encryption algorithm operation, and the value of tK will be modified after the encryption is completed.

After the authentication is completed, the tag has the ability to perform the update step of the random number when receiving the updated content.

The method for automatically updating the random number of the RFID tag of the present invention has the following advantages and beneficial effects:

(1) The present invention abandons the traditional random number generator, uses the encryption algorithm in the label to update the random number, and uses the same set of gate circuits as the encryption algorithm, which greatly saves the design cost of the label and simplifies the complexity of the design of the label;

(2) The encryption algorithm used in the present invention is through security proof, has extremely high security, and encryption algorithm can not appear duplicate result, fully meets the requirement of freshness;

(3) In the present invention, after each legal authentication, the random number in the label will be legally updated, similar to the format of the random number, reducing the algebraic association of the random number before and after;

(4) The present invention ensures the freshness of the tag feedback information, further improves the security of the RFID authentication protocol, and makes the authentication fully resistant to tracking attacks.

Description of drawings

Fig. 1 Schematic diagram of random number automatic update;

The random number automatic update diagram in the example in Figure 2;

Figure 3 is an application example diagram of the update method.

detailed description

Below in conjunction with application example accompanying drawing, the present invention is described in further detail, what used in this example is Rabin encryption algorithm, Shamir A. has carried out security proof (Shamir A.SQUASH-A newMAC with provable security properties) to this encryption algorithm for highly constrained devices such asRFID tags[C]//Proc of Fast Software Encryption. Berlin: Springer, 2008: 144-157). However, the implementation method of the present invention is not limited thereto.

The present invention is realized through the following steps, as shown in Figure 1:

(1) In the tag initialization stage, two random numbers R _new and R _old with a length of L are saved, and tK=1 means that the random number is legally updated (tK=0 means that the random number is not legally updated). Among them, R _new will be used as a label random number in the next authentication, and R _new and R _old will be updated after each legal authentication, but there is no need to save it in the reader;

(2) When the reader/writer sends a request to the tag, the tag will first judge whether the random number is legally updated, that is, judge whether tK is equal to 1. If tK=1, set it to 0 and use R _new as a normal random number; if tK=0, it means that there was an exception in the last authentication. The numbers R _new and R _old are encrypted, R _new '=F<R _new , R _old >, and used as the random number this time, while the original R _new is assigned to R _old ;

(3) After each legal authentication, the reader will generate a random number R _new ' of length L and send it to the tag to update R _new , and assign the last R _new to R _old , and set tK to 1 to indicate a legal update random number.

For the encryption function F in the step (2), the optimal solution is to choose a one-way encryption function, that is, the plaintext cannot be deduced through the ciphertext. In fact, the traditional two-way encryption algorithm is complex in design and consumes a lot of power, which is not suitable for use in lightweight RFID tags. The output of the encryption function F must be the specified L bits. At present, the high-security algorithms that meet this requirement include HASH function, MIXBITS function, Rabin function and so on.

Referring to accompanying drawing 2,3, at first provide the implication of each symbol involved in the method described in this example:

R: reader;

T: label;

KEY: The shared key between the tag and the reader, the length is L;

KEY _old : the shared key used in the last authentication;

KEY _new : the shared key used in this authentication;

ID: the unique identifier of the tag, stored in ciphertext, with a length of 2L;

ID_L: the left half of the ID;

ID_R: the right half of the ID;

r1, r2: the random number generated by the reader when sending the request;

R _new : The reader generates a random number each time the tag is legal, and saves it in the tag;

R _old : The random number used once in the label is used to update the random number R _new ;

Rabin<X>: one-way encryption algorithm, Rabin<X>=[X ² mod M] _L , where X is the encrypted content, M is the modulus, and [] _L is the first L bits of the operation result;

M: modulus, M=2 ^L -1;

XOR: Exclusive OR operation;

&: AND operation.

Before giving a detailed explanation, a hypothesis is given: Since the transmission mode between the RFID system reader and the back-end server system is usually wired transmission, the transmission between the two is safe by default, and the two are viewed as make a whole. As shown in Figure 2, the following is a detailed description of the example:

Message ①: Query, A＝XOR<ID_L, r1>, B＝XOR<ID_R, r2>

The reader generates random numbers r1 and r2, calculates A=XOR<ID_L, r1> and B=XOR<ID_R, r2>, and sends them to the tag together with the authentication request. After receiving A and B, the tag extracts r1=XOR<ID_L,A> and r2=XOR<ID_R,B> in combination with the tag codes ID_L and ID_R saved by itself; at the same time, it judges whether tK is equal to 1. If tK=1, it will After tK is set to 0, calculate C=Rabin<KEY, r1, r2, R _new > and D=XOR<r1, r2, R _new > and send it to the reader; otherwise, use the random number automatic update method to update R _new , Then calculate C and D and send them to the reader. Both C and D calculated here include R _new , which ensures the freshness of the label feedback information and thus has the ability to resist tracking attacks.

Message ②: C＝Rabin<KEY, r1, r2, R _new >, D＝XOR<r1, r2, R _new >

After the reader receives C and D, it extracts R _new ＝XOR<r1,r2,D> through D, and then uses KEY _new or KEY _old to calculate C'=Rabin<KEY _new or KEY _old ,r1,r2, R _new >, match the received C to verify the legitimacy of the tag. After authentication is valid, update KEY _old = KEY _new and KEY _new = Rabin<KEY _old >, and generate a new random number R _new ' at the same time, calculate E=Rabin<KEY _old >&R _new and F=XOR<R _new ,R _new '> sent to the label.

Message ③: E＝Rabin<KEY _old >&R _new , F＝XOR<R _new ,R _new '>

After the tag receives E, it authenticates the legitimacy of the reader by matching with E'=Rabin<KEY>&R _new . If the reader/writer is legal, update KEY=Rabin<KEY>,R _new ,R _old in the tag, and set tK to 1 to indicate legal update. If the reader/writer is invalid, it will not be updated. It should be noted that the R _new ' generated by the reader does not need to be saved in the reader.

So far, the two-way authentication process using the random number automatic update method is over.

This example is to add the label random number automatic update method in the authentication protocol proposed by MA et al., and use the Rabin algorithm as the encryption algorithm in the present invention to realize the automatic update of the random number in the label, instead of the traditional complex random number generator. It ensures the freshness of the tag feedback data, plays a role in resisting tracking attacks, and improves the security of the RFID authentication protocol. Similarly, changing the encryption algorithm to a lightweight HASH algorithm or MIXBITS algorithm can also achieve the same implementation effect.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims (6)

1. the RFID label tag random number automatic update method of a safety, it is characterised in that be contained in following steps:

(1) produce random number after read write line authenticating tag to preserve in the label；

(2) label preserves the random number that read write line transmits, and parameter tK is put the 1 legal renewal of expression；

(3) read write line sends request to label；

(4) when label receives read write line request, parameter tK is judged, if tK=1, enter step (6), if tK=0, enter Step (5)；

(5) use AES that random number is encrypted computing, play regeneration function, tK is set to 0 simultaneously；

(6) random number is applied to this verification process, and carries out subsequent action.

A kind of safe RFID label tag random number automatic update method the most according to claim 1, it is characterised in that: read-write Device possesses random number and produces ability, and label possesses storage random number ability, and amendment parameter tK ability.

A kind of safe RFID label tag random number automatic update method the most according to claim 2, it is characterised in that: read-write After device label in read-write region sends request, the value of parameter tK can be differentiated by label, and is able to carry out encryption calculation Method computing.

A kind of safe RFID label tag random number automatic update method the most according to claim 3, it is characterised in that: label Required encrypted content can be selected when performing AES computing, the value of tK can be modified after having encrypted.

A kind of safe RFID label tag random number automatic update method the most according to claim 1, it is characterised in that: certification After completing, label has the ability to perform the renewal step of random number when receiving update content.

A kind of safe RFID label tag random number automatic update method the most according to claim 1, it is characterised in that: concrete Step is:

Label initial phase preserves two a length of L random number R_newAnd R_old, and preserve tK=1 and represent that random number is legal more Newly, tK=0 represents the most legal renewal of random number, wherein, R_newUse as label random number when certification next time, and close every time R after method certification_newAnd R_oldWill be updated, but without preserving in read write line；

When read write line sends request to label, first label can judge the most legal renewal of random number, i.e. judges that whether etc. tK In 1, if tK=1, then set to 0 and used R_newUse as normal random number；If tK=0, then the last certification of explanation occurs Abnormal, now can use in label for the function F of encryption original random number R preserved_newAnd R_oldIt is encrypted computing R_new'=F < R_new,R_old>, and the random number as this uses, and original R_newThen it is assigned to R_old；

After legitimate authentication, read write line can produce the random number R of a length of L every time_new' be sent in label update R_new, and by upper one Secondary R_newIt is assigned to R_old, tK is put 1 expression legal renewal random number simultaneously.