CN104135727B - A kind of wireless body area network safe transmission method - Google Patents

Abstract

The invention discloses a kind of wireless body area network safe transmission method, it was included with the next stage：1st, system initialization：System is exchanged the clock progress frequency between two adjacent nodes and node and Sink node, is formed two kinds of pairwise key using the clock progress frequency and the clock skew of two nodes of node；2nd, Security routing is formed：After all nodes receive " OK " information, each original AODV routing iinformations of knot removal, using improved AODV agreements formation Security routing and encrypted transmission data；3rd, Data Encryption Transmission：Packet is divided into routing iinformation Data1 and perception data Data2 two parts, encrypted respectively with two kinds of different pairwise key, two adjacent nodes verify mutually Data1, Sink node checking Data2, are then transmitted.This programme supports " plug and play " and ensure that BAN data safeties and privacy, it is adaptable to all BAN networks.

Description

A kind of wireless body area network safe transmission method

Technical field

The present invention relates to wireless network encrypted transmission field, more particularly, to it is a kind of without prepackage key in advance without wire body Domain network security transmission method.

Background technology

Wireless body area network BAN (Body Area Network), is that one kind is worn on monitoring human body life with custodial person The data of perception are sent to BAN Sink by the network of reason and medical data, its sensing node by way of a jump or multi-hop Data further can be transmitted PC or PDA by node, the node, to custodial person（Old man, infant, sportsman, disabled person with And chronic disease patient）There is provided physiological data to monitor in real time, be also widely used for consumer electronics, amusement, motion, ambient intelligence, poultry Herd, the field such as military or safety.Although BAN is WSN（Wireless sensor network, Wireless Sensor Network）Point Branch, has many similitudes with WSN；But BAN is in the side such as deployment way, node type and scale, discharge pattern, delay, mobility Face often assumes to run under conditions of unattended different from general WSN, particularly WSN again, and BAN is to operate in someone's value In the environment kept（Custodial person, medical worker or household）.

Due to the related physiology of the custodial person that sensing node is perceived in BAN and medical data is to medical diagnosis and treats Considerable effect, and also relates to custodial person's privacy problem, thus data safety and privacy are BAN networks A key issue, while the safety measure of clinical practice wishes the simple operations of " plug and play " again.Information is encrypted and section Point certification is the major measure for ensureing secure communication of network, and key Key management is to ensure information privacy, integrality and prevention again The key of illegal node invasion.In general sensing network, it is ensured that data safety mainly has prepackage symmetric key and asymmetric public affairs Two kinds of key technology, but this is not all suitable for BAN networks.

Pre-install symmetric key technique：Because BAN node scales are smaller（General N is less than 50）, it is individual close that each node pre-installs N-1 Key, it is possible to ensure Data Encryption Transmission between any two contact, this surface sees feasible, but there is problems with：

（1）Each BAN must pre-install the N-1 key different from other BAN, otherwise as two patients for dressing BAN Being likely to form pairwise key when close, between two BAN node causes the transmission of mistake；

（2）Due to BAN node foreign peoples, different manufacturers, terminal user are may be from（Medical worker or patient）Give N-1 key of each node distribution in BAN is highly difficult, and they are more desirable to " plug and play " in clinic（Plug-And- Play）Simple operations, i.e. any type of Key distributions and management process should all be minimized, automated and be saturating to user in BSN It is bright；

（3）N-1 key has been pre-installed even across effort, but when finding Key Exposure after BAN work, has been changed in clinic N-1 key of prepackage is also highly difficult.

Asymmetric public key technology：The technology mainly has problems with：

（1）Energy and computing cost are not suitable for resource-constrained sensing node；

（2）Dependence and Operating Complexity to environment limit the application in clinic.

At present, symmetric key encryption data are mainly produced using Human Physiology information and wireless channel attribute in BAN, In the case of not prior shared key, " plug and play " effect is obtained, but both have weak point：

1st, Human Physiology information is utilized

Because BSN networks are the physiologic informations for monitoring people, and physiologic information is difficult to imitate.Many research and utilizations Electroencephalogram（EEG）, photoplethysmogra（PPG）, the physiologic information such as electrocardiogram (ECG), set up hidden passageway to node and letter Breath is authenticated.However, this needs all nodes to possess perception identical signal（EEG or ECG etc.）Ability, it is hard to node Part proposes new requirement；In addition, the sensing node of diverse location measures identical physiological signal with custodial person, it is difficult to Possesses identical accuracy, that is to say, that the accuracy of key recovery is it cannot be guaranteed that 100%.

2nd, the physical attribute of node and wireless channel is utilized

Symmetric key is produced using the physical attribute of the channel characteristics and node itself of BAN/BSN networks it is one and compares New direction, the physical attribute for being easier to obtain mainly has signal intensity (Signal Strength), solves and utilizes human body Key recovery accuracy that physiologic information is brought is it cannot be guaranteed that the problem of 100%.However, because most of wireless sensing nodes are adopted With half-duplex operation, RSS measurement can not simultaneously be carried out in both direction, and the generation of two key between nodes will be undergone to wireless communication Number sampled, quantified, being coordinated（Reconcile）, privacy amplification (Privacy Amplification) four-stage, this band The low efficiency problem of cipher key-extraction is carried out.

State Intellectual Property Office of the People's Republic of China disclosed application publication number on 08 01st, 2012 CN102624530A patent document, title be wireless body area network without the long-range anonymous authentication method of certificate, it passes through public key/private The method that key coordinates realizes the encryption of data, the problem of there is low accuracy and low extraction efficiency.

The content of the invention

The present invention mainly solves that present in prior art plug and play characteristic and accuracy, extraction efficiency can not be taken into account Technical problem there is provided a kind of without pre-install key in advance, in the case where additional firmware need not be increased, with sensing node with The pairwise key encryption data of Sink node and the pairwise key of two adjacent nodes encrypt the thought and method of routing iinformation, support " plug and play " so that ensure that this complicated theory of BAN data safeties and privacy becomes with operability with technical problem With the wireless body area network safe transmission method of practicality.

The present invention is mainly what is be addressed by following technical proposals for above-mentioned technical problem：A kind of wireless body area network Network safe transmission method, including with the next stage：

（1）System initialization：System utilizes the dynamic of the clock progress frequency of node and the clock skew of two nodes With uniqueness, in the case where the Sink node standard time controls, the clock exchanged between two adjacent nodes and node and Sink node enters Spread spectrum rate, forms two kinds of pairwise key；

（2）Security routing is formed：After all nodes receive " OK " information, each original AODV of knot removal（Ad hoc on-demand distance vector routing）Routing iinformation, forms Security routing using improved AODV agreements and adds Close transmission data；

（3）Data Encryption Transmission：Packet is divided into routing iinformation Data1 and perception data Data2 two parts, used respectively Two kinds of different pairwise key encryptions, two adjacent nodes verify mutually Data1, Sink node checking Data2, are then passed It is defeated.

If preferably,CF _x (t) represent nodexIn actual timetTime, clock progress frequencyCF _x ′(t) definition For：

CF _x ′(t)=dCF _x (t)/dt (t>=0) （1）

The time of Sink node is equal to 1 as actual time, the clock progress frequency of actual time；

The clock skew of node 1 and node 2CS ₁₂ (t) be defined asCF ₁ ′(t) andCF ₂ ′(t) difference：

CS ₁₂ (t)= CF ₁ ′(t)- CF ₂ ′(t) （2）

NodexID be designated asID _x ；

System initialization concrete operations are：

（1）Sink node is in single-hop mode into wireless body area network during the standard of all two random intervals of node broadcasts Between stabT ₁ WithT ₂ ；

（2）NodexReceiveT ₁ WithT ₂ Afterwards, formula is used（1）Calculate oneself clock progress frequency be：

CF _x ′(T ₂ -T ₁ )=(CF _x (T ₂ )- CF _x (T ₁ ))/( T ₂ -T ₁ )

NodexPreserveCF _x ′(T ₂ -T ₁ ), and willCF _x ′(T ₂ -T ₁ )+ID _x Sink sections are sent to by original AODV agreements Point, when wireless body area network works, nodexWithK _x Data to perception are encrypted,K _x It is defined as follows：

K _x =F(CF _x ′(T ₂ -T ₁ ),ID _x ) （3）

Here F is key-function, and the key of designated length is produced as needed, but key must is fulfilled for some mathematics Feature.If for example,ID _x Length is 1 byte,CF _x ′(T ₂ -T ₁ ) it is 4 bytes, producing the key of 64 needs basisID _x WithCF _x ′ (T ₂ -T ₁ ) value difference, insertion 3 bytes meet mathematical feature；Key such as can be generated with Hash functions；

（3）NodexWillCF _x ′(T ₂ -T ₁ )+ID _x When being sent to Sink node,xOne jump in the range of neighbor node also can Receive the information and be stored in oneself storage；Equally,xThe clock progress frequency of other nodes can be also received as neighbor node And id information, so, two nodes complete clock progress frequency and exchanged in BAN；

（4）In nodexOnto the path of Sink node, two adjacent nodesm、nThere is the clock progress frequency of other side, at that time Clock offsets the key produced with the ID of two nodesK _mn OrK _nm It is unique, for encrypting routing iinformation, two nodes are mutually recognized each other Card,K _mn OrK _nm It is identical, it is defined as follows：

K _mn =K _nm =F(CS _mn (T ₂ -T ₁ ),ID _m ,ID _n ) （4）

CS _mn (T ₂ -T ₁ ) =ABS(CF _m ′(T ₂ -T ₁ )- CF _n ′(T ₂ -T ₁ ))

Here F is key-function, with formula（3）Identical, ABS is to take absolute value；

（5）Sink node is received after the clock progress frequency and id information of all nodes, Sink node and each nodex Form a pairwise keyK _x , for encryption data in itself, two adjacent nodesm、nForm pairwise keyK _mn OrK _nm , it is used for Encrypt routing iinformation；After Sink node broadcasts " OK " information in single-hop mode, BAN enters Security routing formation and data encryption The transmission stage.

Preferably, after all nodes receive " OK " information, each original AODV routing iinformations of knot removal, using changing The AODV agreements formation Security routing and encrypted transmission data entered；Improved AODV protocol messages are increased on original message basis Plus a clock progress frequency field CF；Work as nodexWhen wishing to Sink node transmission data, first have to send RREQ（Route Request）Then message formation transmit data, data source nodes to the Security routing of Sink node further according to the routexAsk shape It is as follows into the Security routing operation to Sink node：

（1）NodexA RREQ message is produced, each field information in the inside, increased CF words are equally filled with original AODV Section nodex'sCF _x ′(T ₂ -T ₁ ) filling, it is then broadcast to neighbor node；

（2）Work as nodexNeighbor nodemWhen receiving RREQ message, point three kinds of situation operations are as follows：

If A. the CF fields in RREQ message are sky, illustrate that RREQ, from a distrust node, stops forwarding this and disappeared Breath；

If the CF fields B. in RREQ message are present and nodemIn preserve nodexCF valuesCF _x ′(T ₂ -T ₁ ), section PointmWhether equal compare both values, if equal, nodemWith the CF values of oneselfCF _m ′(T ₂ -T ₁ ) replace in RREQ message and save PointxCF values, continue forward the RREQ；Otherwise, stop forwarding；

If the CF fields C. in RREQ message are present and nodemIn without preserve nodexCF values, nodemJust to Sink node requesting nodexCF values, if Sink node has nodexCF values, just willCF _x ′(T ₂ -T ₁ ) useK _m After encryption with Single-hop mode is sent to nodem, nodemThe message is received to be used in combinationK _m After correct decryption, preserveCF _x ′(T ₂ -T ₁ ) in internal memory, after Continuous operation is identical with B；

（3）Work as nodemNeighbor node receive after RREQ message, same to step（2）Similar mode forwards RREQ message；

（4）When Sink node receives RREQ message, a RREP is produced（Being routed back to should）Message, with the CF of Sink node Value filling RREP CF fields, then unicast is returned to the neighbor node of Sink node；

（5）After the neighbor node of Sink node receives RREP message, same to step（2）It is similar to pass RREP message back；

（6）Work as data source nodesxWhen receiving RREP message, the Security routing that only legitimate node is participated in is formed.

Preferably, N1, N2 and N3 are node, it is assumed that N1 to Sink Security routing is N1->N2->N3->Sink, Source node N1 produces the packet by marking Tag, Data1 and Data2 to constitute；Tag is type of message, and Data1 includes source ID, mesh ID and data generation time information are marked, Data2 is the data of N1 actual perceiveds；In encrypted data transmission, node N1, N2, N3 Operated with Sink as follows：

（1）N1：The pairwise key that Data2 is known with only N1 and Sink nodeK ₁Encryption is obtainedE(Data2,K ₁), The Data1 pairwise key that only node N1 and N2 knowK ₁₂It is encrypted asE(Data1,K ₁₂), then packet unicast is transmitted To N2；

（2）N2：First useK ₁₂Data1 is decrypted, i.e.,D(E(Data1,K ₁₂), K ₁₂) Data1 is obtained, obtain after routing iinformation Again with the pairwise key that only node N2 and N3 knowK ₂₃It is encrypted asE(Data1,K ₂₃), then transfer a packet to N3；E is Cryptographic operation, D is decryption oprerations；

（3）N3：First useK ₂₃Data1 is decrypted, i.e.,D(E(Data1,K ₂₃), K ₂₃) Data1 is obtained, obtain after routing iinformation Again with the pairwise key that only node N3 and Sink node are knownK ₃₀It is encrypted asE(Data1,K ₃₀), then transfer a packet to Sink node；

（4）Sink：First useK ₃₀Data1 is decrypted, i.e.,D(E(Data1,K ₃₀), K ₃₀) Data1 is obtained, obtain source node letter After breath, useK ₁Data2 is decrypted, i.e.,D(E(Data2,K ₁), K ₁) obtain True Data Data2.

Encryption and decryption can use conventional algorithm to handle, such as aes algorithm.

The substantial effect that the present invention is brought is on the premise of security is ensured, to meet the characteristic of plug and play, no Need to set key by complicated process, possess good key recovery accuracy, it is also low in the absence of cipher key-extraction efficiency The problem of.

Brief description of the drawings

Fig. 1 is a kind of general BAN structural representations of the present invention；

Fig. 2 is the AODV protocol message structure schematic diagrames of a modification of the present invention；

Fig. 3 is a kind of encryption and the transmitting procedure schematic diagram of the present invention.

Embodiment

Below by embodiment, and with reference to accompanying drawing, technical scheme is described in further detail.

Embodiment：A kind of wireless body area network BAN (Body Arear without pre-installing key in advance of the present embodiment Networks) safe transmission method, is divided into three phases：

（1）System initialization：System initialization need to be carried out in a secure environment, utilize the clock progress frequency of node（It is micro- Second level）, the clock skew Clock Skew of two nodes dynamic and uniqueness, in the case where the Sink standard time controls, exchange two Clock progress frequency between adjacent node and node and Sink, forms two kinds of pairwise key (Pairwise Key)；

（2）Security routing is formed：By the improvement to famous reactive protocols AODV, formed and only have legitimate node to participate in Security routing；

（3）Packet is divided into routing iinformation Data1 and perception data Data2 two parts, respectively with two kinds it is different into Key is encrypted, two adjacent nodes verify mutually Data1, Sink node checking Data2, so both improved encryption, decrypted Efficiency, in turn ensure that data safety and privacy.

First, system model

1 network model

The general BAN structures of the present invention are as shown in figure 1, square nodes are Sink node in figure（ID=0）, it is assumed that：

（1）HaveNIndividual sensing node { S₁,S₂,……,S_NBe deployed in custodial person（In general in BANN<50）, Each node has unique ID (being more than 0), and node is orthogonal（Each node can be independently determined the data of perception）, equipped with identical Wireless communication interface, such as ZigBee；

（2）There is 1 Sink node, its ID=0 collects the data that all sensing nodes are perceived, itself is safe, and And know that node ID and each node in current operation BAN produce the frequency interval of data；

（3）The Sink node power enough due to having can be passed with the mode of a jump mode or multi-hop to all sensing nodes Data are sent, sensing node uses the short-distance transmission of very low-power（It is beneficial to human body）, passed in a multi-hop fashion to Sink node The data of perception are sent, host-host protocol uses AODV；

（4）BAN networks have taken certain Time Synchronization Mechanism, but are different at PPM grades, and it is synchronously safety in itself 's；

（5）When BAN is initialized or addition new node resets, around without malicious node（Grasped by medical worker or guardian Make, can ensure under environment indoors）, in general WSN, often also so assumed；

2 challenge models

Present invention primarily contemplates the confidentiality and integrity of data, challenge model is assumed to：

（1）In range for wireless communication, attacker can arbitrarily eavesdrop the data that each node is sent in BAN, change or prolong Lag to resume to BAN relayings with various power and broadcast；

（2）Attacker can palm off other legitimate nodes, to BAN Web Publishing data falsifications；

（3）Attacker can carry out node capture attack.

2nd, agreement is described

1 clock progress frequency and clock skew

IfCF _x (t) represent nodexIn actual timetTime, clock progress frequency（Referred to as CF）CF _x ′(t) definition For：

CF _x ′(t)=dCF _x (t)/dt (t>=0) （1）

The time of Sink node is equal to 1 as actual time, the clock progress frequency of actual time；

The clock skew of node 1 and node 2CS ₁₂ (t) be defined asCF ₁ ′(t) andCF ₂ ′(t) difference：

CS ₁₂ (t)= CF ₁ ′(t)- CF ₂ ′(t) （2）

Node x ID is designated asID _x ；

Generally, modern processors digital dock has following two attribute：

1st, the clock skew of any clock is stable at a normal temperature；

2nd, each stable clock skew may be considered uniquely.

2 system initializations

In a secure environment, when BAN is powered up or reset（System initialization）When, each node is removed and preserved in memory Original clock progress frequency and routing iinformation, data are transmitted using unmodified AODV, operated as follows：

（1）Sink node is in single-hop mode into wireless body area network during the standard of all two random intervals of node broadcasts Between stabT ₁ WithT ₂ ；

（2）NodexReceiveT ₁ WithT ₂ Afterwards, formula is used（1）Calculate oneself clock progress frequency be：

CF _x ′(T ₂ -T ₁ )=(CF _x (T ₂ )- CF _x (T ₁ ))/( T ₂ -T ₁ )

NodexPreserveCF _x ′(T ₂ -T ₁ ), and willCF _x ′(T ₂ -T ₁ )+ID _x Sink sections are sent to by original AODV agreements Point, when wireless body area network works, nodexWithK _x Data to perception are encrypted,K _x It is defined as follows：

K _x =F(CF _x ′(T ₂ -T ₁ ),ID _x ) （3）

Here F is key-function, and the key of designated length is produced as needed；

（3）NodexWillCF _x ′(T ₂ -T ₁ )+ID _x When being sent to Sink node,xOne jump in the range of neighbor node also can Receive the information and be stored in oneself storage；Equally,xThe clock progress frequency of other nodes can be also received as neighbor node And id information, so, two nodes complete clock progress frequency and exchanged in BAN；

（4）In nodexOnto the path of Sink node, two adjacent nodesm、nThere is the clock progress frequency of other side, at that time Clock offsets the key produced with the ID of two nodesK _mn OrK _nm It is unique, for encrypting routing iinformation, two nodes are mutually recognized each other Card,K _mn OrK _nm It is identical, it is defined as follows：

K _mn =K _nm =F(CS _mn (T ₂ -T ₁ ),ID _m ,ID _n ) （4）

CS _mn (T ₂ -T ₁ ) =ABS(CF _m ′(T ₂ -T ₁ )- CF _n ′(T ₂ -T ₁ ))

Here F is key-function, with formula（3）Identical, ABS is to take absolute value；

（5）Sink node is received after the clock progress frequency and id information of all nodes, Sink node and each nodex Form a pairwise keyK _x , for encryption data in itself, two adjacent nodesm、nForm pairwise keyK _mn OrK _nm , it is used for Encrypt routing iinformation；After Sink node broadcasts " OK " information in single-hop mode, BAN enters Security routing formation and data encryption The transmission stage.

3 Security routings are formed

After all nodes receive " OK " information, each original AODV routing iinformations of knot removal, using improved AODV Agreement formation Security routing and encrypted transmission data.Improved AODV protocol messages are when increasing by one on original message basis Clock progress frequency field CF, as shown in Figure 2；Form the method CF verification process similar to original AODV but many of route.Work as section PointxWish to Sink node send data when, first have to send RREQ ask to form Sink Security routing, then further according to The route transmits data, data source nodesxRequest formation to Sink Security routing operation is as follows：

（1）NodexA RREQ message is produced, each field information in the inside, increased CF words are equally filled with original AODV Section nodex'sCF _x ′(T ₂ -T ₁ ) filling, it is then broadcast to neighbor node；

（2）Work as nodexNeighbor nodemWhen receiving RREQ message, point three kinds of situation operations are as follows：

If A. the CF fields in RREQ message are sky, illustrate that RREQ, from a distrust node, stops forwarding this and disappeared Breath；

If the CF fields B. in RREQ message are present and nodemIn preserve nodexCF valuesCF _x ′(T ₂ -T ₁ ), section PointmWhether equal compare both values, if equal, nodemWith the CF values of oneselfCF _m ′(T ₂ -T ₁ ) replace in RREQ message and save PointxCF values, continue forward the RREQ；Otherwise, stop forwarding（Illustrate that RREQ may be from a personation node）；

If the CF fields C. in RREQ message are present and nodemIn without preserve nodexCF values, this be probably by The result that network topology structure changes is caused in human motion or different gestures.NodemJust to Sink node requesting nodex CF values, if Sink node has nodexCF values, just willCF _x ′(T ₂ -T ₁ ) useK _m Section is sent in single-hop mode after encryption Pointm, nodemThe message is received to be used in combinationK _m After correct decryption, preserveCF _x ′(T ₂ -T ₁ ) in internal memory, subsequent operation is identical with B；

（3）Work as nodemNeighbor node receive after RREQ message, same to step（2）Similar mode forwards RREQ message；

（4）When Sink node receives RREQ message, a RREP message is produced, with the CF values of Sink node（Equal to 1） RREP CF fields are filled, then unicast is returned to the neighbor node of Sink node；

（5）After the neighbor node of Sink node receives RREP message, same to step（2）It is similar to pass RREP message back；

（6）Work as data source nodesxWhen receiving RREP message, the Security routing that only legitimate node is participated in is formed.

4 encrypted data transmissions

After Security routing is formed, data source nodes just can transmit data to Sink, and it is encrypted with transmitting procedure such as Shown in Fig. 3.

In figure 3, N1, N2 and N3 are node, it is assumed that N1 to Sink Security routing is N1->N2->N3->Sink, source Node N1 produces the packet by marking Tag, Data1 and Data2 to constitute；Tag is type of message, and Data1 includes source ID, target ID and data generation time information, Data2 are the data of N1 actual perceiveds；In encrypted data transmission, node N1, N2, N3 and Sink operations are as follows：

（1）N1：The pairwise key that Data2 is known with only N1 and Sink nodeK ₁Encryption is obtainedE(Data2,K ₁), The Data1 pairwise key that only node N1 and N2 knowK ₁₂It is encrypted asE(Data1,K ₁₂), then packet unicast is transmitted To N2；

（2）N2：First useK ₁₂Data1 is decrypted, i.e.,D(E(Data1,K ₁₂), K ₁₂) Data1 is obtained, obtain after routing iinformation again With the pairwise key that only node N2 and N3 knowK ₂₃It is encrypted asE(Data1,K ₂₃), then transfer a packet to N3；E is to add Close operation, D is decryption oprerations；

（3）N3：First useK ₂₃Data1 is decrypted, i.e.,D(E(Data1,K ₂₃), K ₂₃) Data1 is obtained, obtain after routing iinformation Again with the pairwise key that only node N3 and Sink node are knownK ₃₀Data1 is encrypted, i.e.,E(Data1,K ₃₀), then by packet Send Sink node to；

（4）Sink：First useK ₃₀Data1 is decrypted, i.e.,D(E(Data1,K ₃₀), K ₃₀) Data1 is obtained, obtain source node letter After breath, useK ₁Data2 is decrypted, i.e.,D(E(Data2,K ₁), K ₁) obtain True Data Data2.

5 safety analysis

Add and " insert i.e. from key dynamic with accuracy, passively with active attack, node capture, new node below With " in terms of analyze we invent security：

（1）Key dynamic and accuracy：Two kinds of keys that initialization is produced every time are dynamic, and this is due to Sink sections The standard time interval of point broadcast is random, and CF changes with environment temperature again, cipher key calculation formula（3）、（4）And and node ID（Uniquely）Binding, thus, two kinds of keys are unique again；

The present invention will not be brought produces the accuracy problem that symmetric key recovers using physiologic information, also not from wireless communication The physical attribute in road extracts the low efficiency problem of key；Because CF is calculated by node oneself, it is not necessary to which a node goes to survey The CF of another node is measured, two adjacent nodes complete the exchange of CF values in a secure environment, do not have cipher key-extraction process.

（2）Passive attack：The data that each node is sent in BAN can be eavesdropped with infinite approach BAN by eavesdropping node；Due to section Point data bag is divided into two parts, is encrypted respectively with two kinds of different pairwise key, the legitimate node on Security routing is only known Which node is data come from, and does not also know the content of track data；Even if earwig is aware of key-functionF, do not know steathily yet The information listened is sent by which node, does not also know which neighbor node is received, earwig's analysis keyK _mn It is highly difficult, andK _x And withxID be closely related, thus hardly result in real Data2.

（3）Active attack

Three kinds of main manifestation modes to active attack are analyzed：

Reset：For attacker, outdated data is only reset just meaningful.It is assumed that attacker pretends to be nodexBroadcasted When data（Make no modifications, simply delay forwarding）, onlyxNeighbor nodeiCan correctly it decryptE(Data1,K _xi ), obtain Send routing information, be transmitted toiNeighbor node, other nodes are due to can not correctly decryptE(Data1,K _xi ) and stop forwarding；But BAN the whole network time synchronizeds,xNode can judge whether the packet is out-of-date with a time thresholding, even in the thresholding time Interior, data have passed to Sink node, Sink node the data can also be compared with the last data of the node and abandon it is out-of-date Data are simultaneously alarmed；

Personation：Personation is exactly that attacker palms off legitimate node ID to Sink node transmission data falsification.It is assumed that personation node Power is sufficiently large, and the legitimate node in all BAN/BSN can receive the message that personation node is sent.If it is one to palm off node Individual new node, Security routing will be initially formed before sending data, need to be authenticated node due to forming Security routing, Suo Youhe In method node（Containing Sink）The CF information of node is not palmed off, it is impossible to set up routing iinformation, thus spurious information can not be sent To Sink node；If palming off a legitimate nodexSend data falsification, attacker must be toxNeighbor nodeiThere is providedx's CF information；Attacker can not form route due to no item data, thus can not transmit personation legitimate node to Sink Data.

Distort：Distorting is reset again after changing data, that is, attacker have modified Data2（Data1 is unmodified）, will close Method nodexPacket retransmit once；WithxAdjacent legitimate node all receives the spurious information, but AODV rows into route It is unicast transmission, does not existxNode on to Sink routes will not show interest in the spurious information, in routing tablexNeighbor nodei （First hop node）With with legitimate nodexBetween keyK _xi DecryptionE(Data1,K _xi )（Intermediate node does not verify Data2）, do not send out Existing mistake, data can be sent to Sink node, but Sink node can not be usedK _x DecryptionE(Data2,K _x ), thus abandon the data simultaneously Alarm.

（4）Node is captured

It is assumed that node is captured (losing or other approach), after legitimate node leaves custodial person for a period of time, become to dislike Meaning node is returned in original BAN；This period, attacker can obtain the CF of CF and its neighbor node in legitimate node, can To pass through key-functionTwo kinds of pairwise key are calculated, that is, BAN does not have any secret to say that challenge model is also examined Consider such case.Because BAN belongs to Attended mode network, node foreign peoples and irredundant node, when there is node loss, first Sink is in the range of certain time（Node produces the interval of data）Certain node failure or loss can be perceived and alarmed；Secondly, Even if it was found that node capture attack（Patient, medical worker are easier to find node loss or are replaced）, remove malice contact Afterwards, it need to only be powered back up resetting in a secure environment, Sink broadcasts newT ₁ WithT ₂ , when malicious node is again introduced into BAN, because The CF information that last time produces has not been used, and can not equally carry out passive and active attack.

（5）New node is added and " plug and play "

When needing to add new sensing node in original BAN, only need in a secure environment, new node to be installed to being supervised After with shield person, a power-on reset is performed just；Say to be exactly to re-start system initialization from inside（Key is produced）, safety Route is formed, three processes of encrypted data transmission；Inherently one push-botton operation of power-on reset is said from outside, to medical matters people Member, domestic monitoring people etc. are exercisable, it is not necessary to special professional knowledge, thus meet " plug and play ".

Specific embodiment described herein is only to spirit explanation for example of the invention.Technology neck belonging to of the invention The technical staff in domain can be made various modifications or supplement to described specific embodiment or be replaced using similar mode Generation, but without departing from the spiritual of the present invention or surmount scope defined in appended claims.

Although more having used the terms such as node, progress frequency, skew herein, it is not precluded from using other terms Possibility.It is used for the purpose of more easily describing and explaining the essence of the present invention using these terms；It is construed as any A kind of additional limitation is all disagreed with spirit of the present invention.

Claims (2)

1. a kind of wireless body area network safe transmission method, it is characterised in that including with the next stage：

（1）System initialization：System using node clock progress frequency and two nodes clock skew dynamic with only One property, in the case where the Sink node standard time controls, the clock exchanged between two adjacent nodes and node and Sink node enters spread spectrum Rate, forms two kinds of pairwise key；

（2）Security routing is formed：After all nodes receive " OK " information, each original AODV routing iinformations of knot removal are adopted With improved AODV agreements formation Security routing and encrypted transmission data；

（3）Data Encryption Transmission：Packet is divided into routing iinformation Data1 and perception data Data2 two parts, respectively with two kinds Different pairwise key encryptions, two adjacent nodes verify mutually Data1, Sink node checking Data2, are then transmitted；

IfCF _x (t) represent nodexIn actual timetTime, clock progress frequencyCF _x ′(t) be defined as：

CF _x ′(t)=dCF _x (t)/dt (t>=0) （1）

The time of Sink node is equal to 1 as actual time, the clock progress frequency of actual time；

The clock skew of node 1 and node 2CS ₁₂ (t) be defined asCF ₁ ′(t) andCF ₂ ′(t) difference：

CS ₁₂ (t)= CF ₁ ′(t)- CF ₂ ′(t) （2）

Node x ID is designated asID _x ；

System initialization concrete operations are：

（First 1）Sink node is with the standard time of single-hop mode all two random intervals of node broadcasts into wireless body area network StampT ₁ WithT ₂ ；

（First 2）NodexReceiveT ₁ WithT ₂ Afterwards, formula is used（1）Calculate oneself clock progress frequency be：

CF _x ′(T ₂ -T ₁ )=(CF _x (T ₂ )- CF _x (T ₁ ))/( T ₂ -T ₁ )

NodexPreserveCF _x ′(T ₂ -T ₁ ), and willCF _x ′(T ₂ -T ₁ )+ID _x Sink node is sent to by original AODV agreements, when When wireless body area network works, nodexWithK _x Data to perception are encrypted,K _x It is defined as follows：

K _x =F(CF _x ′(T ₂ -T ₁ ),ID _x ) （3）

Here F is key-function, and the key of designated length is produced as needed；

（First 3）NodexWillCF _x ′(T ₂ -T ₁ )+ID _x When being sent to Sink node,xOne jump in the range of neighbor node can also receive The information is simultaneously stored in oneself storage；Equally,xThe clock progress frequency and ID of other nodes can be also received as neighbor node Information, so, two nodes complete clock progress frequency and exchanged in BAN；

（First 4）In nodexOnto the path of Sink node, two adjacent nodesm、nThere are the clock progress frequency of other side, its clock The key that the ID of skew and two nodes is producedK _mn OrK _nm It is unique, for encrypting routing iinformation, two nodes are mutually recognized each other Card,K _mn OrK _nm It is identical, it is defined as follows：

K _mn =K _nm =F(CS _mn (T ₂ -T ₁ ),ID _m ,ID _n ) （4）

CS _mn (T ₂ -T ₁ ) =ABS(CF _m ′(T ₂ -T ₁ )- CF _n ′(T ₂ -T ₁ ))

Here F is key-function, with formula（3）Identical, ABS is to take absolute value；

（First 5）Sink node is received after the clock progress frequency and id information of all nodes, Sink node and each nodexShape Into a pairwise keyK _x , for encryption data in itself, two adjacent nodesm、nForm pairwise keyK _mn OrK _nm , for adding Close routing iinformation；After Sink node broadcasts " OK " information in single-hop mode, BAN enters Security routing formation and data encryption is passed The defeated stage；

After all nodes receive " OK " information, each original AODV routing iinformations of knot removal, using improved AODV agreements Form Security routing and encrypted transmission data；Improved AODV protocol messages are to increase a clock on original message basis to enter Spread spectrum rate field CF；Work as nodexWhen wishing to Sink node transmission data, first have to transmission RREQ and ask to form Sink node Security routing, then further according to the route transmit data, data source nodesxThe Security routing that request is formed to Sink node is grasped Make as follows：

（Second 1）NodexA RREQ message is produced, each field information in the inside, increased CF fields are equally filled with original AODV Use nodex'sCF _x ′(T ₂ -T ₁ ) filling, it is then broadcast to neighbor node；

（Second 2）Work as nodexNeighbor nodemWhen receiving RREQ message, point three kinds of situation operations are as follows：

If A. the CF fields in RREQ message are sky, illustrate that RREQ, from a distrust node, stops forwarding the message；

If the CF fields B. in RREQ message are present and nodemIn preserve nodexCF valuesCF _x ′(T ₂ -T ₁ ), nodemThan It is whether equal compared with both values, if equal, nodemWith the CF values of oneselfCF _m ′(T ₂ -T ₁ ) replace RREQ message interior jointsx's CF values, continue to forward the RREQ；Otherwise, stop forwarding；

If the CF fields C. in RREQ message are present and nodemIn without preserve nodexCF values, nodemJust saved to Sink Point requesting nodexCF values, if Sink node has nodexCF values, just willCF _x ′(T ₂ -T ₁ ) useK _m With single-hop side after encryption Formula is sent to nodem, nodemThe message is received to be used in combinationK _m After correct decryption, preserveCF _x ′(T ₂ -T ₁ ) in internal memory, subsequent operation It is identical with B；

（Second 3）Work as nodemNeighbor node receive after RREQ message, same to step（Second 2）Similar mode forwards RREQ message；

（Second 4）When Sink node receives RREQ message, a RREP message is produced, fills RREP's with the CF values of Sink node CF fields, then unicast is returned to the neighbor node of Sink node；

（Second 5）After the neighbor node of Sink node receives RREP message, same to step（Second 2）It is similar to pass RREP message back；

（Second 6）Work as data source nodesxWhen receiving RREP message, the Security routing that only legitimate node is participated in is formed.

2. a kind of wireless body area network safe transmission method according to claim 1, it is characterised in that N1, N2 and N3 are For node, it is assumed that N1 to Sink Security routing is N1->N2->N3->Sink, source node N1 produce by mark Tag, Data1 and The packet of Data2 compositions；Tag is type of message, and Data1 includes source ID, Target id and data generation time information, Data2 For the data of N1 actual perceiveds；In encrypted data transmission, node N1, N2, N3 and Sink operation are as follows：

（The third 1）N1：The pairwise key that Data2 is known with only N1 and Sink nodeK ₁Encryption is obtainedE(Data2,K ₁), Data1 With the pairwise key that only node N1 and N2 knowK ₁₂It is encrypted asE(Data1,K ₁₂), then send packet unicast to N2；

（The third 2）N2：First useK ₁₂Data1 is decrypted, i.e.,D(E(Data1,K ₁₂), K ₁₂) Data1 is obtained, obtain after routing iinformation again With the pairwise key that only node N2 and N3 knowK ₂₃It is encrypted asE(Data1,K ₂₃), then transfer a packet to N3；E is to add Close operation, D is decryption oprerations；

（The third 3）N3：First useK ₂₃Data1 is decrypted, i.e.,D(E(Data1,K ₂₃), K ₂₃) Data1 is obtained, obtain after routing iinformation again With the pairwise key that only node N3 and Sink node are knownK ₃₀It is encrypted asE(Data1,K ₃₀), then transfer a packet to Sink node；

（The third 4）Sink：First useK ₃₀Data1 is decrypted, i.e.,D(E(Data1,K ₃₀), K ₃₀) Data1 is obtained, obtain source node identification Afterwards, useK ₁Data2 is decrypted, i.e.,D(E(Data2,K ₁), K ₁) obtain True Data Data2.