**2.3 Multipath routing protocol**

For an effective data delivery, multipath routing protocol generates a multipath (primary and secondary paths) from the source node to the destination node. It uses secondary path in case the primary path fails. With this, fault tolerance is achieved. However, this increases the cost of routing through the cost of maintaining multiple paths between source and destination [10, 16]. There are different types of multipath-based routing protocols.

*Wireless Sensor Networks (WSNs): Security and Privacy Issues and Solutions DOI: http://dx.doi.org/10.5772/intechopen.84989*

### *2.3.1 Disjoint path routing protocol*

the network. Low-energy adaptive clustering hierarchy (LEACH), thresholdsensitive energy-efficient sensor network protocol (TEEN) and adaptive threshold-sensitive energy-efficient sensor network protocol (APTEEN), and secure hierarchical energy-efficient routing (SHEER) are examples of hierarchical routing protocol. TEEN gives a very good performance since it reduces the number of transmissions [14]. Patil et al. presented SHEER in [15]. It uses adaptive probabilistic transmission mechanism for determining the optimal route in WSN. SHEER also adopts hierarchical key establishment scheme (HIKES) for key distribution, authentication, and confidentiality. SHEER involves four phases as described below:

1.The base station (BS), computes key *KR* ¼ *HMAC I*ð Þ *<sup>R</sup>*k*OR* , generates a

2.BS broadcasts the initiation call as *Nb* k *IR* k *OR* k *EncKR init* k *Nb* k *NR* k*N*<sup>00</sup>

3.On receiving the initiation message, the sensor node extracts and decrypts

the received initiation message. If they are similar, then the base station is successfully authenticated. It then replaces *NR* in the newly with *N*<sup>0</sup>

During the neighbor discovery phase, the sensor nodes establish their hopping link with their neighboring node. Each node switches from listening mode to transmission mode. In listening mode, node sends a HELLO message containing its identity, a nonce, and an encrypted header with the sensor key until it gets a reply

In this phase, cluster consisting of certain number of nodes with a cluster head is

Each sensor sends its data to the base station through the cluster heads. This

For an effective data delivery, multipath routing protocol generates a multipath (primary and secondary paths) from the source node to the destination node. It uses secondary path in case the primary path fails. With this, fault tolerance is achieved. However, this increases the cost of routing through the cost of maintaining multiple

paths between source and destination [10, 16]. There are different types of

centralize data transmission reduces collision within clusters.

where *init* is the initiation call, *OR* is the index, *OR* is the offset of *KR*, and *Nb* is

*<sup>R</sup>* ¼ *EncKR* ð Þ *NR* . The

,

*R*

*<sup>R</sup>*, sets its

*<sup>R</sup>* and keeps *IR* and *OR*.

*<sup>R</sup>*, and compares it with the *NR* in

broadcast authentication token *NR*, and encrypts it as *N<sup>l</sup>*

base station pre-loads each sensor node with *N<sup>l</sup>*

*Wireless Mesh Networks - Security, Architectures and Protocols*

*R* , regenerates *N*<sup>0</sup>

time stamp generated by BS.

*EncKR init* k *Nb* k *NR* k*N*<sup>00</sup>

*2.2.2 Neighbor discovery phase*

from its neighboring nodes.

selected based on some parameters.

*2.2.4 Data message exchange phase*

**2.3 Multipath routing protocol**

multipath-based routing protocols.

**16**

*2.2.3 Clustering phase*

timer and starts the next phase.

*2.2.1 Initiation phase*

In a disjoint path routing protocol, every source node finds the shortest disjointed multipath to the sink node. It evenly shares its data load among these disjointed paths. All the paths in this multipath share no sensor node. The protocol is reliable with extra overhead but at a low energy.

### *2.3.2 Braided path routing protocol*

To construct braided multipath, the protocol first selects the primary path; then for every sensor, the best path is chosen from source to sink node, but this path does not include the primary node. The best alternative paths that are not necessarily disjoint from the primary path are called idealized braided multipath. These alternative paths are located either on the primary path or very close to it which means that the energy consumption on both the primary path and an alternative path is almost equal [17].

### *2.3.3 N to 1 multipath discovery routing protocol*

N to 1 multipath discovery protocol is a protocol based on flooding. Example of N to 1 multipath-based routing protocol is multipath-based segment-by-segment routing (MSSR) protocol proposed by Lu et al. in [18]. MSSR protocol divides a single path into multiple segments, where multiple node-disjoint paths are discovered and independently maintained. N to 1 multipath discovery routing protocol reduces congestion, and effectively manages.

### **2.4 Location-based routing protocol**

Location-based routing protocol routes data based on the distance of the source and destination nodes. It calculates the distance between source and destination nodes in order to determine estimated routing energy. Shruti [19] proposed a location-based routing protocol. The protocol uses the signal strength of the incoming signal to determine their distance. In their protocol, all the non-active nodes are put in sleeping mode in order to save energy. In location-based, the knowledge of the position of sensor nodes is exploited to route the query from the base station to the event. Location information enables the network to select the best route.

Another example of the location-based protocol is the geographic adaptive fidelity (GAF) protocol for mobile adhoc networks (MANETs). GAF conserves energy, and reduces routing overhead, which makes suitable for WSNs. Other examples of location-based protocols are location-aided routing (LAR), energyefficient location-aided routing (EELAR), greedy location-aided routing protocol (GLAR), etc.

### **2.5 Quality of service (QoS)-based routing protocol**

QoS-based routing protocol balances effective data delivery of the data to the sink node with some predetermined QoS metrics [17, 20]. Some of the existing QoS-based routing protocols are described below:

### *2.5.1 Sequential assignment outing (SAR) protocol*

SAR protocol uses energy, QoS on each path, and the priority level of each packet as the QoS metrics to achieve effective data delivery. SAR protocol discovers and uses multiple paths from the sink node to sensor nodes for effective data delivery. SAR protocol considers energy efficiency and fault tolerance and also focuses on minimizing the average weighted QoS metric during data transfer [21]. **3.1 Security and privacy issues**

*DOI: http://dx.doi.org/10.5772/intechopen.84989*

attacks on WSNs are discussed below.

*3.1.1 Manipulating routing information*

all the nodes involved in the multi-hop).

*3.1.2 Sybil attack*

**19**

computed.

The increase in demand for a real-time information has made WSN become more expedient. WSNs most of the time employs multi-hop transmission mode to overcome their constraints. The major problem of multi-hop transmission is attacks on the source data and nodes' identities during hopping. For a resource-constraint WSN with source node sending data to the destination through several intermediary nodes, there is a possibility of intrusion, identity tracing by an adversary, gleaning, and modification of source data by the intermediary nodes. WSNs, most times, operate in hostile environments and can be subjected to side channel attacks, such as differential power analysis. In these attacks, the adversary monitors the system, repeats the same operation, and takes careful measurements of power consumed in a cycle-by-cycle basis in order to either recover the secret key or perturb used in the perturbation. To prevent this, a scalar blinding is usually engaged in cryptographic-based security solutions. The scalar multiplication is blinded using integer *m*, where *m* is the order of the point *P*∈ *Eq*, such that *mP* ¼ 0.

*Wireless Sensor Networks (WSNs): Security and Privacy Issues and Solutions*

For example, instead of computing *Q* ¼ *kP mod q*, *Q* ¼ ð Þ *k* þ *m P mod q* is

another location will be detected by the base station when comparing the

use [21]. However, this requires pre-assignment of keys to sensor node.

embellished path identity with hash of all the appended pseudonyms or identities of

In this attack, adversary compromises the WSN by creating fake identities to disrupt the network protocols. Sybil attack can lead to denial of services. It may also affect mapping during routing, since a Sybil node creates illegal identities in a bid to break down the one-to-one mapping between each node. Sybil is common in P2P networks and also extends to wireless sensor networks [8]. Moreover, detection and defense against Sybil attack is more challenging; this is due to the limited energy and computational capabilities of WSNs. Different efforts had been developed to thwart Sybil attack in WSN. An example is the use of a pair-wise key-based detection scheme which sets a threshold for the number of the identity that a node can

Another way to thwart Sybil attack is to validate identity of every node involved in routing. This can be reactively or proactively done. Reactively means prior to

Another issue in WSNs is how to preserve the identities of the source and destination nodes from the privy of intermediary nodes and adversaries during multi-hop. That is, there must be a form of lightweight authentication feature(s) inherent in the data packet between a source and destination nodes. Some other

This attack targets the routing information between two sensor nodes. It can be launched through spoofing or replaying the routing information. This can be done by adversaries who have the capability of creating routing loops, attracting or repelling network traffic, and extending or shortening source routes. This attack is a passive attack which is not only easy to launch but elusive to detection. However, a unique identity can be created for the selected path (using key-based hash function of the pseudonyms or identity of all the selected intermediate nodes and embellishes in the message, any attempt to record data packet from a location and re-tunnel it at

### *2.5.2 SPEED protocol*

SPEED is also an example of QoS-based routing protocol. In SPEED, every sensor node keeps its neighboring node information in order to increase the performance of the protocol. For example, SPEED protocol has congestion avoidance mechanism that is used to avoid congestion. The mechanism relies on the node information. Routing module in SPEED is called stateless geographic nondeterministic forwarding (SGNF) and works together with four modules at the network layer. In this protocol, the total energy used for transmission is incomparable to the performance of the routing algorithm.

### *2.5.3 QoS-aware and heterogeneously clustered routing (QHCR)*

It is an energy-efficient routing protocol used by heterogeneous WSNs for delaysensitive, bandwidth-hungry, time-critical, and QoS-aware applications. The QHCR protocol provides dedicated paths for real-time applications as well as delaysensitive applications at a lower energy. The QHCR protocol consists of information gathering, cluster head selection, and intra-cluster communication phases.

### **2.6 Mobility-based routing protocol**

Mobility-based routing protocol is a lightweight protocol that ensures data delivery from source to destination nodes. Tree-based efficient data dissemination protocol (TEDD), scalable energy-efficient asynchronous dissemination (SEAD), two-tier data dissemination (TTDD), and data MULES are some of the examples of mobility-based routing protocol. These routing protocols deal with the dynamism of the topology of the network. The closest node to the sink node tends to transmit more than others, which reduces its lifetime faster than other nodes [22]. Another example of the mobility-based routing protocol was the protocol proposed by Kim et al. [23]. The authors proposed a temperature-aware mobility algorithm for wireless sensor networks. Their algorithm employs store-and-carry mechanism to overcome the challenges posed by human postural mobility. In their store-and-carry-based routing protocol, routing packets are stored in a temporary memory called buffer. The buffer reroutes lost data to any intermediary node that temporarily lost connection with the source node. Their protocol also uses temperature to determine the intermediary node.

Another example of mobility protocol is the routing protocol proposed by Kumar et al. in [24]. They use ant colony optimization (ACO) and endocrine cooperative particle swarm optimization (ECPSO) algorithms to enhance the performance of the WSNs.

### **3. Security and privacy issues in WSN**

Most of the existing WSN routing protocols and existing security solutions are unsuitable for WSNs. This is due to resources constraint associated with WSNs [25]. These constraints majorly determine the kind of security approaches that can be adopted for WSNs. Various security issues and their solutions are described in this section.

### **3.1 Security and privacy issues**

and uses multiple paths from the sink node to sensor nodes for effective data delivery. SAR protocol considers energy efficiency and fault tolerance and also focuses on minimizing the average weighted QoS metric during data transfer [21].

*Wireless Mesh Networks - Security, Architectures and Protocols*

SPEED is also an example of QoS-based routing protocol. In SPEED, every sensor node keeps its neighboring node information in order to increase the performance of the protocol. For example, SPEED protocol has congestion avoidance mechanism that is used to avoid congestion. The mechanism relies on the node information. Routing module in SPEED is called stateless geographic nondeterministic forwarding (SGNF) and works together with four modules at the network layer. In this protocol, the total energy used for transmission is incomparable to

It is an energy-efficient routing protocol used by heterogeneous WSNs for delaysensitive, bandwidth-hungry, time-critical, and QoS-aware applications. The QHCR protocol provides dedicated paths for real-time applications as well as delaysensitive applications at a lower energy. The QHCR protocol consists of information

Mobility-based routing protocol is a lightweight protocol that ensures data delivery from source to destination nodes. Tree-based efficient data dissemination protocol (TEDD), scalable energy-efficient asynchronous dissemination (SEAD), two-tier data dissemination (TTDD), and data MULES are some of the examples of mobility-based routing protocol. These routing protocols deal with the dynamism of the topology of the network. The closest node to the sink node tends to transmit more than others, which reduces its lifetime faster than other nodes [22]. Another example of the mobility-based routing protocol was the protocol proposed by Kim et al. [23]. The authors proposed a temperature-aware mobility algorithm for wireless sensor networks. Their algorithm employs store-and-carry mechanism to overcome the challenges posed by human postural mobility. In their store-and-carry-based routing protocol, routing packets are stored in a temporary memory called buffer. The buffer reroutes lost data to any intermediary node that temporarily lost connection with the source node. Their protocol also uses temperature to determine the intermediary node. Another example of mobility protocol is the routing protocol proposed by Kumar et al. in [24]. They use ant colony optimization (ACO) and endocrine cooperative particle swarm optimization (ECPSO) algorithms to enhance the per-

Most of the existing WSN routing protocols and existing security solutions are unsuitable for WSNs. This is due to resources constraint associated with WSNs [25]. These constraints majorly determine the kind of security approaches that can be adopted for WSNs. Various security issues and their solutions are

gathering, cluster head selection, and intra-cluster communication phases.

*2.5.2 SPEED protocol*

the performance of the routing algorithm.

**2.6 Mobility-based routing protocol**

formance of the WSNs.

described in this section.

**18**

**3. Security and privacy issues in WSN**

*2.5.3 QoS-aware and heterogeneously clustered routing (QHCR)*

The increase in demand for a real-time information has made WSN become more expedient. WSNs most of the time employs multi-hop transmission mode to overcome their constraints. The major problem of multi-hop transmission is attacks on the source data and nodes' identities during hopping. For a resource-constraint WSN with source node sending data to the destination through several intermediary nodes, there is a possibility of intrusion, identity tracing by an adversary, gleaning, and modification of source data by the intermediary nodes. WSNs, most times, operate in hostile environments and can be subjected to side channel attacks, such as differential power analysis. In these attacks, the adversary monitors the system, repeats the same operation, and takes careful measurements of power consumed in a cycle-by-cycle basis in order to either recover the secret key or perturb used in the perturbation. To prevent this, a scalar blinding is usually engaged in cryptographic-based security solutions. The scalar multiplication is blinded using integer *m*, where *m* is the order of the point *P*∈ *Eq*, such that *mP* ¼ 0. For example, instead of computing *Q* ¼ *kP mod q*, *Q* ¼ ð Þ *k* þ *m P mod q* is computed.

Another issue in WSNs is how to preserve the identities of the source and destination nodes from the privy of intermediary nodes and adversaries during multi-hop. That is, there must be a form of lightweight authentication feature(s) inherent in the data packet between a source and destination nodes. Some other attacks on WSNs are discussed below.

### *3.1.1 Manipulating routing information*

This attack targets the routing information between two sensor nodes. It can be launched through spoofing or replaying the routing information. This can be done by adversaries who have the capability of creating routing loops, attracting or repelling network traffic, and extending or shortening source routes. This attack is a passive attack which is not only easy to launch but elusive to detection. However, a unique identity can be created for the selected path (using key-based hash function of the pseudonyms or identity of all the selected intermediate nodes and embellishes in the message, any attempt to record data packet from a location and re-tunnel it at another location will be detected by the base station when comparing the embellished path identity with hash of all the appended pseudonyms or identities of all the nodes involved in the multi-hop).

### *3.1.2 Sybil attack*

In this attack, adversary compromises the WSN by creating fake identities to disrupt the network protocols. Sybil attack can lead to denial of services. It may also affect mapping during routing, since a Sybil node creates illegal identities in a bid to break down the one-to-one mapping between each node. Sybil is common in P2P networks and also extends to wireless sensor networks [8]. Moreover, detection and defense against Sybil attack is more challenging; this is due to the limited energy and computational capabilities of WSNs. Different efforts had been developed to thwart Sybil attack in WSN. An example is the use of a pair-wise key-based detection scheme which sets a threshold for the number of the identity that a node can use [21]. However, this requires pre-assignment of keys to sensor node.

Another way to thwart Sybil attack is to validate identity of every node involved in routing. This can be reactively or proactively done. Reactively means prior to

routing, a node must provide enough identification parameters to differentiate it from all other sensor nodes. The most common method is a resource test. Another way is to increase the cost against the benefit in identity generation [8]. That is, increasing cost of creating an identity and reducing the possible of having multiple identities will thwart Sybil attack, since the goal of a Sybil attacker is to acquire more identities. Also, traceable pseudonym and network-node identity generated by base station can be used to prevent a Sybil attack [9, 26].

neighboring nodes. An adversary may exploit this to deceive sensor nodes

*Wireless Sensor Networks (WSNs): Security and Privacy Issues and Solutions*

*DOI: http://dx.doi.org/10.5772/intechopen.84989*

shown below:

*3.1.4.3 Denial of service attack*

messages sent by neighboring nodes [33].

**3.2 Security and privacy solutions**

*3.2.1 Use of effective key management*

protocols in WSNs.

**21**

receiving the HELLO packet that they are within the radio range of the source node. In [30], the authors proposed a new method for detecting the HELLO flood attack based on distance. Here, nodes not only compare the RSS of the received HELLO packet but also compare the node's distance to the selected cluster head (CH) with the threshold distance. Only those nodes whose RSS as well as distance falls within the threshold limits are allowed to join the network. For example, in the setup phase of LEACH protocol [31], CH sends its own location coordinates. The nodes receiving HELLO packets from CH calculate the distance *Dist* as

*Dist* ¼ *sqrt sq x* ½ � ð Þþ 2 � *x*1 *sq y* ð Þ 2 � *y*1

Here, (x1; y1) are the coordinates of the sensor node receiving the packet, and (x2; y2) are the coordinates of CH. Each sensor node calculate the radio signal strength value (*RSS*) and distance between (*Dist*). These are used to determine the cluster they belong in, that is, if ð Þ *RSS* <*ThRSS and Dist*<*ThDist* then Node ¼

This type of attack exploits the weaknesses in the sensor network, by attempting to disrupt the sensor network. Denial of service (DoS) attack denies services to valid users [32]. In a safety-critical network, this kind of attack can be disastrous to the functionality of the network. One of the methods engaged by adversary to launch DoS is by flooding the network with messages in order to increase traffics on the network. The DOS attack can be detected through proper filtration of incoming messages based on the contents and identifying nodes with high number of faulty messages. Faulty messages are detected by checking for the contradiction between

Recently, application of WSN has gained massive attention leading to new security challenges and design issues [34]. In this section, we discussed relevant research efforts on the development of security schemes for WSN using different approaches such as effective key management, public key infrastructure (PKI), multiclass nodes, as well as grouping of nodes to improve the security of routing

Du et al. presented a scheme with an example of an effective key management. Their scheme takes advantage of the high-end sensors in the heterogeneous networks. The performance evaluation and security analysis of their scheme show that the key management scheme provides better security with less complexity than the existing key management schemes [35]. The protocol pre-assigns a few keys in the L-sensor and a few keys to every H-sensor. This is because H-sensor is tamper-proof

and has a larger memory than L-sensor. Their scheme uses asymmetric predistribution (AP) key management scheme since the number of pre-distributed

keys in an H-sensor and in an L-sensor is different [12].

'Friend of the cluster' otherwise not a friend of the cluster.

### *3.1.3 Sinkhole attack*

This attack prevents the sink node (base station) from obtaining the complete and correct data from the sensors, thus posing a threat to higher layer applications. In this attack, an adversary makes itself receptively attractive to its neighboring nodes in order to direct more traffics to itself [27, 28]. This results in adversary attracting all the traffics that is meant for the sink node. The adversary can then launch a more severe attack on the network, like selective forwarding, modifying, or dropping the packets. WSN is more vulnerable to this attack because its nodes most of the time send data to the base station [29].

Meanwhile, a point-to-point authentication between source node, identifiable intermediate nodes, and end-to-end symmetric encryption between source and destination nodes can be used prevent sinkhole, Sybil, and sinkhole attacks. The attack is foiled once the adversary could not decrypt end-to-end symmetric encrypted data even if it successfully impersonates the node and receives its data packet [9].

### *3.1.4 Clone attack*

In a clone attack, the attacker first attacks and captures the legitimate sensor nodes from the WSNs, collects all their information from their memories, copies them on multiple sensor nodes to create clone nodes, and finally deploys them to the network. Once a node is clone, adversary can then launch any other attacks. There are two different ways of detecting this attack: centralized and distributed approaches. Centralized uses sink node to detect and foil the activities of clone nodes, while distributed approach uses selected nodes to detect clone nodes and foil their activities in the network. Distributed approach is suitable for static WSNs because distributed techniques use nodes' location information to detect clones and sensor nodes with the same identity, but different addresses are taken as clone nodes. Meanwhile, in mobile WSNs, it is a different thing entirely, sensor nodes keep changing their position, and these nodes keep joining and leaving the network. Hence, node location information is not considered as the best technique for detecting clone nodes. Clone node can launch the following attacks:

### *3.1.4.1 Selective forwarding attack*

Multi-hop-based WSN routing protocols assumed that all the neighboring nodes must re-hop their received data packets. Malicious nodes selectively forward some packets while dropping the others. Selective forwarding attacks are most effective when the adversary is actively involved in the data flow.

### *3.1.4.2 HELLO flood attack*

This attack utilizes the connection between nodes. Most routing protocols require sensor nodes to broadcast HELLO packets to announce themselves to their *Wireless Sensor Networks (WSNs): Security and Privacy Issues and Solutions DOI: http://dx.doi.org/10.5772/intechopen.84989*

neighboring nodes. An adversary may exploit this to deceive sensor nodes receiving the HELLO packet that they are within the radio range of the source node. In [30], the authors proposed a new method for detecting the HELLO flood attack based on distance. Here, nodes not only compare the RSS of the received HELLO packet but also compare the node's distance to the selected cluster head (CH) with the threshold distance. Only those nodes whose RSS as well as distance falls within the threshold limits are allowed to join the network. For example, in the setup phase of LEACH protocol [31], CH sends its own location coordinates. The nodes receiving HELLO packets from CH calculate the distance *Dist* as shown below:

$$Dist = sqrt[sq(\varkappa2 - \varkappa1) + sq(\jmath2 - \jmath1)]$$

Here, (x1; y1) are the coordinates of the sensor node receiving the packet, and (x2; y2) are the coordinates of CH. Each sensor node calculate the radio signal strength value (*RSS*) and distance between (*Dist*). These are used to determine the cluster they belong in, that is, if ð Þ *RSS* <*ThRSS and Dist*<*ThDist* then Node ¼ 'Friend of the cluster' otherwise not a friend of the cluster.

### *3.1.4.3 Denial of service attack*

routing, a node must provide enough identification parameters to differentiate it from all other sensor nodes. The most common method is a resource test. Another way is to increase the cost against the benefit in identity generation [8]. That is, increasing cost of creating an identity and reducing the possible of having multiple identities will thwart Sybil attack, since the goal of a Sybil attacker is to acquire more identities. Also, traceable pseudonym and network-node identity generated

This attack prevents the sink node (base station) from obtaining the complete and correct data from the sensors, thus posing a threat to higher layer applications. In this attack, an adversary makes itself receptively attractive to its neighboring nodes in order to direct more traffics to itself [27, 28]. This results in adversary attracting all the traffics that is meant for the sink node. The adversary can then launch a more severe attack on the network, like selective forwarding, modifying, or dropping the packets. WSN is more vulnerable to this attack because its nodes

Meanwhile, a point-to-point authentication between source node, identifiable intermediate nodes, and end-to-end symmetric encryption between source and destination nodes can be used prevent sinkhole, Sybil, and sinkhole attacks. The attack is foiled once the adversary could not decrypt end-to-end symmetric encrypted data even if it successfully impersonates the node and receives its data packet [9].

In a clone attack, the attacker first attacks and captures the legitimate sensor nodes from the WSNs, collects all their information from their memories, copies them on multiple sensor nodes to create clone nodes, and finally deploys them to the network. Once a node is clone, adversary can then launch any other attacks. There are two different ways of detecting this attack: centralized and distributed approaches. Centralized uses sink node to detect and foil the activities of clone nodes, while distributed approach uses selected nodes to detect clone nodes and foil their activities in the network. Distributed approach is suitable for static WSNs because distributed techniques use nodes' location information to detect clones and sensor nodes with the same identity, but different addresses are taken as clone nodes. Meanwhile, in mobile WSNs, it is a different thing entirely, sensor nodes keep changing their position, and these nodes keep joining and leaving the network. Hence, node location information is not considered as the best technique for

Multi-hop-based WSN routing protocols assumed that all the neighboring nodes must re-hop their received data packets. Malicious nodes selectively forward some packets while dropping the others. Selective forwarding attacks are most effective

This attack utilizes the connection between nodes. Most routing protocols require sensor nodes to broadcast HELLO packets to announce themselves to their

detecting clone nodes. Clone node can launch the following attacks:

when the adversary is actively involved in the data flow.

by base station can be used to prevent a Sybil attack [9, 26].

*Wireless Mesh Networks - Security, Architectures and Protocols*

most of the time send data to the base station [29].

*3.1.3 Sinkhole attack*

*3.1.4 Clone attack*

*3.1.4.1 Selective forwarding attack*

*3.1.4.2 HELLO flood attack*

**20**

This type of attack exploits the weaknesses in the sensor network, by attempting to disrupt the sensor network. Denial of service (DoS) attack denies services to valid users [32]. In a safety-critical network, this kind of attack can be disastrous to the functionality of the network. One of the methods engaged by adversary to launch DoS is by flooding the network with messages in order to increase traffics on the network. The DOS attack can be detected through proper filtration of incoming messages based on the contents and identifying nodes with high number of faulty messages. Faulty messages are detected by checking for the contradiction between messages sent by neighboring nodes [33].

### **3.2 Security and privacy solutions**

Recently, application of WSN has gained massive attention leading to new security challenges and design issues [34]. In this section, we discussed relevant research efforts on the development of security schemes for WSN using different approaches such as effective key management, public key infrastructure (PKI), multiclass nodes, as well as grouping of nodes to improve the security of routing protocols in WSNs.

### *3.2.1 Use of effective key management*

Du et al. presented a scheme with an example of an effective key management. Their scheme takes advantage of the high-end sensors in the heterogeneous networks. The performance evaluation and security analysis of their scheme show that the key management scheme provides better security with less complexity than the existing key management schemes [35]. The protocol pre-assigns a few keys in the L-sensor and a few keys to every H-sensor. This is because H-sensor is tamper-proof and has a larger memory than L-sensor. Their scheme uses asymmetric predistribution (AP) key management scheme since the number of pre-distributed keys in an H-sensor and in an L-sensor is different [12].

### *3.2.2 Use of effective public key infrastructure*

Yu in [36] solved the security problem in WSN using the public key cryptography as a tool to ensure the authenticity of the sink node or base station. The approach consists of two phases; the first phase is node to sink handshake phase, where sink and sensor nodes set up session keys for secure data exchange. In the second phase, the session keys are used to encrypt data. Their scheme is very easy to implement, and requires a low computational power. The only limitation of their scheme is that all the participating nodes in the network have to agree on a common key prior to the exchange of data. However, any scheme based on a single key is vulnerable to the key compromise. That is, a compromised sensor node will not only compromise the shared key but also the whole network.

Also, Chen et al. [37] presented a PKI-based approach to ensure secure keys exchange in the WSNs. Their scheme provides key management mechanism for wireless sensor network applications that can handle sink mobility and deliver data to neighboring nodes and sinks without failure. They also presented a method for detecting and thwarting DoS attack and data authentication encryption.

### *3.2.3 Effective use of multiclass nodes*

Du et al. [38] presents a new secure routing protocol for heterogeneous sensor networks (HSNs), which is a two-tier secure routing (TTSR) protocol. The TTSR protocol consists of both intra-cluster routing and inter-cluster routing schemes. The intra-cluster routing forms a minimum spanning tree (shortest path tree) among L-sensors in a cluster for data forwarding. In case of inter-cluster routing, data packets are sent by H-sensors in the relay cells along the direction from the source node to the sink node. The tree-based routing and relay via relay cells of TTSR make it resistant to spoofing, selective forwarding, and sinkhole and wormhole attacks.

scheme for distributed wireless sensor networks; their scheme involves three entities: one or more sink nodes, Y number of group dominator nodes, and

*Wireless Sensor Networks (WSNs): Security and Privacy Issues and Solutions*

*DOI: http://dx.doi.org/10.5772/intechopen.84989*

Point-to-point security solution involves secure routing between every two nodes along the multi-hop path. To show the design and efficacy of point-to-point solution, we fully describe a typical point to point security solution for multi-hop based WSNs proposed in [9]. Olakanmi and Dada [9] proposed an effective pointto-point security scheme that engages point-to-point (PoP) mutual authentication scheme, perturbation, and pseudonym to overcome security and privacy issues in WSNs. To reduce computational cost and energy consumption, they used elliptic curve cryptography, hash function, and exclusive OR operations to evolve an efficient security solution for a decentralized WSNs. The network model, as shown in **Figure 3**, consists of base station (BS), immediate node (IN), source node (SN) or (sn), and destination node (DS) or (ds). The SNs and DSs are capable of multi-hop transmission; therefore any SN can become DS and vice

The PoP security scheme consists of the following phases: registration and key management, secure data exchange, perturbs generation, signature and obfusca-

The serial number ψ of each node is sent to BS. BS then generates unique

is the generator of elliptic curve *Eq* and *q* is the order of *E*.

computes and distributes its public parameter *φ* = (*ρ* + *μ*)*P mod q*, where *P*

*<sup>q</sup>* ∗ , as its master secret key pair, and

tion, authentication, and verification and decryption phases.

*3.2.5.1 Registration and key management phase*

pseudonym and network-node identity as follows:

i. BS randomly generates *s*, *ρ*∈ *Z* <sup>∗</sup>

N number of ordinary sensor nodes.

*Wireless sensor network system model.*

*3.2.5 Point-to-point security solution*

versa.

**23**

**Figure 3.**

Du [39] also proposed a novel QoS routing protocol that includes bandwidth calculation and slot reservation for mobile ad hoc networks (MANETS). Their QoS routing protocol takes advantage of the numerous transmission ability of multiclass nodes. Their protocol used three encryption keys:


The QoS routing protocol divides transmission data into different data slices. Each slice is route through a unique route of the discovered multipath.

### *3.2.4 Effective grouping of nodes to improve security of wireless sensor networks*

In group-based WSN security scheme, the dominating node processes the sensed information locally and prepares the authenticated report for the destination node [40]. In this category, sensor nodes are grouped into smaller clusters wherein each cell assigns a special sensor node to carry out all the burden of relaying multi-hop packets. Hence division of labor is possible in the network, which makes the scheme to consume low power. Zhang et al. in [41] presented a group-based security

*Wireless Sensor Networks (WSNs): Security and Privacy Issues and Solutions DOI: http://dx.doi.org/10.5772/intechopen.84989*

### **Figure 3.** *Wireless sensor network system model.*

*3.2.2 Use of effective public key infrastructure*

*Wireless Mesh Networks - Security, Architectures and Protocols*

*3.2.3 Effective use of multiclass nodes*

wormhole attacks.

discovery phase

**22**

compromise the shared key but also the whole network.

class nodes. Their protocol used three encryption keys:

1.A public key known by the sink and all other nodes

3.A share primary key between node and sink node

Yu in [36] solved the security problem in WSN using the public key cryptogra-

Also, Chen et al. [37] presented a PKI-based approach to ensure secure keys exchange in the WSNs. Their scheme provides key management mechanism for wireless sensor network applications that can handle sink mobility and deliver data to neighboring nodes and sinks without failure. They also presented a method for

Du et al. [38] presents a new secure routing protocol for heterogeneous sensor networks (HSNs), which is a two-tier secure routing (TTSR) protocol. The TTSR protocol consists of both intra-cluster routing and inter-cluster routing schemes. The intra-cluster routing forms a minimum spanning tree (shortest path tree) among L-sensors in a cluster for data forwarding. In case of inter-cluster routing, data packets are sent by H-sensors in the relay cells along the direction from the source node to the sink node. The tree-based routing and relay via relay cells of TTSR make it resistant to spoofing, selective forwarding, and sinkhole and

Du [39] also proposed a novel QoS routing protocol that includes bandwidth calculation and slot reservation for mobile ad hoc networks (MANETS). Their QoS routing protocol takes advantage of the numerous transmission ability of multi-

2.Node private key shared by two neighbor nodes and refreshed in the route

The QoS routing protocol divides transmission data into different data slices.

In group-based WSN security scheme, the dominating node processes the sensed information locally and prepares the authenticated report for the destination node [40]. In this category, sensor nodes are grouped into smaller clusters wherein each cell assigns a special sensor node to carry out all the burden of relaying multi-hop packets. Hence division of labor is possible in the network, which makes the scheme to consume low power. Zhang et al. in [41] presented a group-based security

Each slice is route through a unique route of the discovered multipath.

*3.2.4 Effective grouping of nodes to improve security of wireless sensor networks*

detecting and thwarting DoS attack and data authentication encryption.

phy as a tool to ensure the authenticity of the sink node or base station. The approach consists of two phases; the first phase is node to sink handshake phase, where sink and sensor nodes set up session keys for secure data exchange. In the second phase, the session keys are used to encrypt data. Their scheme is very easy to implement, and requires a low computational power. The only limitation of their scheme is that all the participating nodes in the network have to agree on a common key prior to the exchange of data. However, any scheme based on a single key is vulnerable to the key compromise. That is, a compromised sensor node will not only

> scheme for distributed wireless sensor networks; their scheme involves three entities: one or more sink nodes, Y number of group dominator nodes, and N number of ordinary sensor nodes.
