Research of ZigBee’s data security and protection

Research of ZigBee’s data security and protectionLi Chunqing1, Zhang Jiancheng11College of Computer Science and Software,Tianjin Polytechnic University, NO.63 in Chenglinzhuang Road,Hedong District,Tianjin, 300160,Chinafranklcq@ABSTRACT: With the fast development of the wireless communication technology, the ZigBee technology, as a new short-distance wireless network technology, has been used much more widely in the area of wireless network. Its security meets not only confidentiality, but also low-power, low complexity, low-cost and so on. Therefore, it is particularly important to study the data security protection of ZigBee technology deeply. This paper discusses the ZigBee’s Security system, wireless data transmission network and researches on the data encryption and decryption of the ZigBee technology. A number of existent issues and the future development of ZigBee technology have been analyzed and summarized. What’s more, in order to expand the range of ZigBee’s application, it is necessary to combine the ZigBee technology with IPv6.KEYWORDS: ZigBee technology; Wireless data transmission; encryption and decryption; CCM ModelI.INTRODUCTIONThe fast development of wireless communication and electronic device technology has urged the development and the application of low power loss, the low price and the multi-purpose miniature sensor. In general, along with signal distance enlargement, the cost of the equipment complexity, the power loss as well as the system is increasing. Compared with the existing kinds of wireless communication technologies, ZigBee technology will be the technology[1] of the lowest power loss and cost. Meanwhile, because of the ZigBee technology’s low data rate and small communication range, it has made the ZigBee technology be used in the small load data current capacity business.ZigBee alliance forecasts the main application domain, including industry control, consumption electronic installation, automobile automation, agricultural automation and medical device control. In many applications, it needs high security in the sensor network. Therefore, the security problem becomes the restriction of wireless sensor network’s development. In the paper, it mainly studies the ZigBee protocol stack architecture, the security key, the network architecture as well as the trust center which uses the safety mechanism to conduct the research, and proposes the existing questions in the security aspect as well as the trend of ZigBee technology development in security aspect.II.ZIGBEE SECURITY SYSTEMThe ZigBee equipment uses the IEEE 802.15.4 wireless protocol to communicate with others. This standard assigns two: Physical Layer (PHY) and Media Access Control Layer (MAC) [2].The ZigBee protocol stack is composed of the physical layer, the data link layer, the network layer (NWK) as well as the application layer (APL)[3].Physical layer takes charge of basic wireless correspondence which is made up of modulation, transmission, data encryption and acception. The link layer provides the equipment with Single-hop Communication as well as the reliable transmission and the communication’s security. The network layer mainly provides the general network function, for example, topology building and maintenance, addressing and security route. Application layer includes application support sub-layer, ZigBee equipment object and different kinds of application objects. Application support sub-layer supplies the security and the mapping management service. ZDO (ZigBee Device Object, ZigBee equipment object) is responsible for the equipment management, including the security policy and the safe configuration management. The application layer provides services for ZDO and the ZigBee application service.2009 International Forum on Computer Science-Technology and ApplicationsThis framework of the system includes protocol stack’s three safety mechanisms. MAC, NWK and APS (the APL level including one application support sub-layer) are responsible for the respective frame’s safety transmission. Moreover, the APS sub-layer provides services for the establishment and maintenance of security relationship. ZDO manages secure strategy and equipment security structure. Figure 1 has demonstrated the ZigBee protocolstack Full View.Figure 1. ZigBee protocol stack’s security architectureZigBee uses three basic keys, respectively the network key, the link key and the host key, which are used in the data encryption process. The network key can be applied in the data link layer, the network layer and the application layer while the main key and the link key are used in the application layer and its sub-layer.III. ZIGBEE WIRELESS DATA TRANSMISSIONNETWORKThe ZigBee standard has defined three types of equipments, which are the ZigBee Coordinator, the ZigBee router and the ZigBee terminal device. The ZigBee Coordinator is responsible for starting and configuring network, only one ZigBee Coordinator in a ZigBee network. The ZigBee router is one kind of the support connection equipments. There are many routers in a network. The router can retransmit the message to other equipments, but it does not support the ZigBee router in the star network. The ZigBee terminal device may carry out the related function, and reaches other correspond equipment using the network. ZigBee network framework is shown in Figure 2.ZigBee CoordinatorZigBee RouterZigBee Terminal EquipmentFigure 2. ZigBee network architectureSimply speaking, similar to CDMA and the GSM network, ZigBee is a high reliable wireless data transmission network. ZigBee data transmission module is similar to the Mobile network base stations. To ZigBee, its effective coverage scope is from 10 meters to 75meters. However, based on the size of actual transmitting power and a varietyof different application models, its scope can be extended to be several hundred meters, which can basically cover the home or office environment. ZigBee can be a wireless data transmission network platform which is composed of a maximum of 65000 nodes. In the entire network, each ZigBee node can communicate with each other. Based on this, the transmission distance of ZigBee can be extended from the standard 75meters.Different from the mobile communication CDMA network or the GSM net, the ZigBee network is mainly established for the industrial automation control data transmission [7]. Thus, it must have the characteristics of simplicity, easy-operating, reliability and low price. Its each base value is less than 1000RMB. However, mobilecommunication webmaster is built for the audio communication. Each base station costs generally above 1,000,000 Yuan. Each ZigBee node can not only regard itself as the monitoring object, for example its sensor carries on the data acquisition and monitoring directly, but also transfer automatically the data information which another node passes on. In addition, each ZigBee node (FFD) can also wirelessly connect many isolated sub-nodes which don’t transfer the network information in its own signal cover scope.IV.DATA ENCRYPTION AND DECRYPTIONThe ZigBee technology has provided different security policies in view of the different applications[4].These strategies exert separately on the data link layer, the network layer and the application layer, using the AES2128 encryption algorithm to guarantee data security under the CCM3 pattern. The CCM3 pattern is an improvement of the CCM pattern[5], which is made up of the Cipher Block Chaining Message Authentication Code (Ci-pher Block Chaining--MAC, CBC--MAC) pattern and the counter (Counter, CTR) pattern. CCM3 pattern execution includes input transformation, authentication transformation and encryption transformation, which use the following parameters:z A bit string key, its length keylen is 128;z The length of the authentication field M (0, 4, 6, 8, 10, 12, 14, 16);z The message field length L (2, 3, ⋯, 8);z The length of m byte string territory isl(m) byte, its value scope is 0≤ l (m) < 28L;z The length of N value domain is 15 - L, for at any one range when using the same key, N value isunique;z The length of da byte string territory is l (da) byte, its value scope is 0 ≤l (da) < 264;Their concrete realization of the process is as follows:A.Input TransformationInput transformation is as follows: inputing the encryption data m and data authentication da, by these following steps:1)Make sure a byte string’s field length l(da) bytes to form L (da) bytes string.a) L (da) = 0, then L (da) for the empty string;b) 0 <l (a) <216 - 28, then L (da) will encrypt l (da) of the two bytes;c) 216 - 28≤ l(da) <232, then L (da) is 0xff, 0xfe, and the four bytes of l (a) which will be encrypted to the right connection;d) 232≤ l (da) <264, then L (da) is 0xff, 0xff, and the8 bytes of l (da) which will be encrypted to the right connection.2) L (da), right to connect da forms the result string.3) Using the result string to form an additional authentication data (AddAtData), the Data is produced by right connection to non-negative zero; the additional data can be divided by 16.4) Using the same method to form an additional message data (PlainData), the data is formed by the way of connecting encrypted data m right to non-negative zero, the additional data must be divided by 16.5) Finally, authentication data (AuthData) is generated, which is composed of the data AddAtData and data PlainData, that is, To AuthData = AddAtData‖PlainData.B.Authentication TransformationAfter Data AuthData generated, transform it with signs. Their concrete realization of the process is as follows:1) to form a byte flag field (Flags), which is made up of 1 bit express reservation (Reserved), 1 bit Hdata, 3 bits M, and 3 bits L, namely: Flags = Reserved ‖ Hdata ‖M ‖ L.In the formula, 1 bit “Reserved” is used for future expansion when set to 0; when l (a) = 0 , a Adata will be set to 0, otherwise, will be set to 1; 3 L domains stand for an integer L - 1; when M> 0, 3 M domain stand for an integer (M - 2) / 2, otherwise, set to 0.2) generate 16 bytes B0 field, which is made up of 1 byte flag field (Flags), 15 - L bytes N domain and L bytes that is the length of the l (m) domain, namely: B0 = Flags ‖ N ‖ l (m).3) separate data AuthData into A1‖A2‖⋯‖At, where each data block is a 16-byte string, then the CBC-MAC value is defined as:X 0 = 0128, Xi + 1: = E(Xi⊕Ai,Key) f or i = 0, ⋯, tE(X,K) that the use of key K to encrypt the plaintext X by the function E; 0128 stand for that all the 16 bytes is 0. Then Seeking reauthentication mark T, which is a MAC value, by obtaining the front M bytes of the ciphertext Xi + 1, namely: T: = first-M-bytes (Xi + 1).C.Encryption TransformationWhen plaintext data (PlainData) and authentication flagT have been established, the process of using encrypt transformation to encryption is as follows:1) Generate a byte flag field (Flags), which is made up of 2 bits expressed reservations (Reserved), 3 integer bits 0 and 3 bits integer domain L, namely: Flags = Reserved ‖Reserved ‖ 0 ‖L .In the formula, 2 bits “Reserved” are used for future expansion when set to 0, 3 integer bits express L-1 and 3 bits zero domain express L;2) Generate 16 bytes Ai field, which is made up of 1 bits expressed byte flag field (Flags), 15-N bytes N domain and L bytes expressed integer i, namely:Ai = Flags ‖N‖ Counter i for i = 0, 1, 2 ⋯3) separate message data PlainData into M1‖M2‖⋯‖M t, where each message block Mi is a 16 b ytes string .ciphertext blocks C1, ⋯, Ct are defined as: Ci: = E(Ai, Key)⊕Mi for i = 1, 2, ⋯, t.4) Ciphertext comes from the left l (m) bytes of C1‖C2‖⋯‖Ct.5) Find the 16 bytes encryption blocks S0as: S0: = E(A0,Key ).6) Encrypted authentication symbol U is gained by the dense flow of Chi U of S0 with the left-most M-byte XOR authentication flag T . The specific value is as follows: U: = T⊕first-M-bytes (S0)If this operation is right, encrypted message c can be made up of connecting the ciphertext right to Encrypted authentication symbol, the last is output.D. Decryption TransformationAfter obtaining the encryption key K, the length of the M authentication domain and encryption message msg, you can decrypt the cipher text, the process is as follows:1) Resolve the receiving message msg into E‖U. The right-most string U is a M bytes string. If this operation fails, the output will be invalid and stopped. U is the encrypted authentication symbol; the length of left string E is l(msg) - M bytes.2) Generate an additional message CipherData. It is generated by the way of right connecting string C and non-negative zero. CipherData can be divisible by 16.3) Similarly, use encryption transformation process; enter the demand parameters “CipherData” and authentication symbol. Here, the decomposition of Ciphertext message is CipherData, it is broken down into each block Ci which is a 16 bytes string.4) The output string is N‖T. The right-most string Tis a M bytes string. T is the authentication mark.The l (msg )- M bytes string of the left-most string N is regarded as the output of the plaintext message.In short, ZigBee technology can ensure transmission of information security and prevent eavesdropping or interception of the attacker by utilizing a security policy. Thereby, it ensures the security of wireless transmission.V.CONCLUSIONThe key success of ZigBee technology is its abundance and convenient application. In security aspect, Literature [6] think the AES-128 encryption algorithms can ensure the data security of the ZigBee wireless transmission. Moreover, NIST also estimates that the AES - 128 encryptions can be at least used safely till year 2036[7]. But literature[8] think the sole symmetrical encryption algorithm possibly brings the security hidden danger in the data encryption and the key exchange. In view of this, the author has proposed an improved data encryption and decryption algorithm in order to ensure the data security of the ZigBee wireless transmission, on the base of the analysis of ZigBee security system and network structure. Meanwhile, the author suggests the elliptic curve public-key encryption method should be applied in ZigBee technology as non-symmetric plan[9].Because there is a huge address spaces in IPv6, so it can assign a global network address for each ZigBee node. Meanwhile, it can provide good QoS and safe communication support. Therefore, the combination of IPv6 and the ZigBee will be a hot spot in the future study.REFERENCES[1]Quanping Wang, Li Wang.The introduction of ZigBeetechnology[J].COMMUNICATIONS WORLD,2003,4(101):41--43.[2]Xiaopei Nie. 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