# Information-Aware Secure Routing in Wireless Sensor Networks
## 2 Related Work  
In recent years, numerous research works have addressed the problem of secure routing in WSNs. The existing methods for secure routing fall into five categories. 1. Identity authentication. Identity authentication is mainly used to determine the sender of information and exchange communication keys between two communication parties. Since nodes in a WSN are relatively easy for attackers to capture, we can use identity authentication mechanisms to verify the captured nodes [12; 13; 14; 15]. Due to the constrained computing and energy capabilities, identity authentication via a symmetric key algorithm is more feasible than the traditional approach based on public key encryption in WSNs [3; 16]. 2. Message authentication. Message authentication allows the receiver to determine whether a message has been altered in transmission. A code is attached to each message by the sender and verified by the receiver. A possible way to attack a WSN that implements message authentication is to exhaust the limited power of the sensor nodes by sending a large number of fake messages (e.g., flood attacks). However, the attack can be effectively resisted by randomly pre-allocating coupled keys to adjacent nodes or any pair of sensor nodes [17; 18]. 3. Intrusion detection. Intrusion detection is used to detect and isolate malicious nodes by collecting and analyzing information in WSNs. Intrusion detection mechanisms for traditional networks cannot be directly applied to WSNs because of the limited power, network bandwidth, computing capacity, and storage capacity in WSNs. The authors of [19] proposed an intrusion detection scheme for WSNs based on game theory and an autoregressive model. It is mentioned in [20] that a machine learning anomaly detection system for multicast communication could be constructed. 4. Multipath routing. In this method, we can construct multiple paths for a pair of sensor nodes and only choose one path to transmit data using a certain strategy. Multipath routing can improve the reliability of data transmission and balance the load for the network. In [10; 21], multiple paths were established by utilizing the redundancy of wireless sensor nodes to ensure the reliability of data transmission. The authors of [22] presented a multipath routing protocol to ensure network security by building node disjoint paths. 5. Secure routing on trust. Trust is defined as a subjective evaluation, and a node (trustor) is in charge of determining the trust levels of other nodes (trustees) by examining the actions that they perform. The trust values affect the action of the trustor node [8]. Methods for trust evaluation are usually classified into two categories: Direct and indirect. Direct trust evaluation assesses the past behaviors of participants, whereas indirect trust evaluation assesses the past behaviors of peers in the neighborhood [23; 24]. A trust model is suitable for secure routing in WSNs because it is lightweight. Several trust models have been proposed for secure routing in WSNs, and they are grouped into the following types: 1. Bayesian trust model. Through mathematical calculation and data fitting, Bayesian theory can perfectly describe the change law of trust. It utilizes prior probability events to update the latest relevant evidence, and then it predicts subsequent behaviors [25; 26; 27]. 2. Game theory trust model. Game theory attempts to explain how to use an opponent's behavior to make correct decisions about behavioral strategies through mathematical methods. The trust model based on game theory is used to identify and exclude uncooperative selfish nodes from the normal network [28; 29; 30]. 3. Fuzzy trust model. The fuzzy trust model relies on a series of fuzzy rules to deal with the uncertainty in trust evaluation. Then, fuzzy theory can be used to evaluate the trust value and select the trusted route [31; 32; 33]. 4. Directed and undirected graph model.