The lifetime of a sensor network is generally longer than that of a single sensor node, so to ensure the connectivity of the network, new nodes need to be deployed into the network in multiphase. Such networks are called multiphase sensor networks. In sensor networks, establishing a pairwise key between two neighboring nodes is a fundamental security requirement. However, for sensor nodes with strictly limited capabilities, there are great challenges in establishing a pairwise key between two neighboring sensor nodes deployed at different phases. In order to solve this problem, some scholars have proposed some solutions based on backward key-chains and forward key-chains, however, how to further improve the networks’ resilience against node capture attacks still needs further research; and some scholars have proposed some solutions based on key pools of each phase are independent, but how to improve the probability of establishing a pairwise key between two neighboring nodes deployed at different phases is still a very challenging problem. In this article, we propose a new pairwise key scheme based on deployment knowledge. Theoretical analysis and simulation show that the proposed model can achieve high probability of establishing a pairwise key between two neighboring nodes and good resilience against node capture attacks by setting appropriate parameters.

Sensor networks are often deployed outdoors and are more susceptible to various attacks. In order to protect communication between nodes, scholars have proposed key management schemes. The most popular among them is the key predistribution scheme. This scheme has the following contradiction: in order to improve security, the number of keys predistributed to nodes should be minimized as much as possible. However, as the number of predistribution keys decreases, the network may no longer be securely connected, resulting in wastage of nodes. In this letter, we propose a new key establishment method to address this issue. Analysis and simulation show that the proposed scheme can reduce the number of predistribution keys in the original schemes while ensuring secure network connectivity.

In multi-phase sensor networks, each deployment is called a phase of networks, and how to improve the secure connectivity between nodes deployed at different phases is a key issue. But this is not an easy task for resource-constrained sensor nodes. Recently, some scholars have proposed some methods where nodes deployed at the same phase can establish shared keys directly, which offers perfect resilience against destruction. Additionally, they introduced an online key update method to establish shared keys for nodes deployed at different phases. However, the resilience of this scheme decreases rapidly as the number of newly deployed nodes captured during the key establishment phase increases. In this paper, we propose a T-type key pre-distribution scheme based on deployment knowledge, and also introduce a novel method for path key establishment. In this scheme, the shared keys established directly between nodes exhibit perfect resilience. Furthermore, this scheme does not require the assumption of a relatively secure time period during the key establishment phase. In this proposed scheme, by setting appropriate parameters, theoretical analysis and simulation show that the probability of two neighboring nodes establishing a shared key is about 1, and the resilience against node capture attacks is excellent.

Unattended wireless sensor networks (UWSNs), in which mobile sinks (MSs) are responsible for the data collection, and which are vulnerable to multiple attacks. For example, the adversaries can initiate MS replication attack after compromising a large number of sensor nodes (SNs). To resist such attacks, some scholars have proposed some schemes. In these schemes, it is assumed that MSs are equipped with tamper resistance hardware, so they are pre-distributed most of keys of a key pool for achieving authentication with SNs. However, in outdoor and even sensitive areas, tamper-resistant hardware is not always absolutely safe. Once MSs are compromised, networks become insecure. In this paper, we propose a secure model. The model contains three types of nodes, namely SNs, MSs, and a base station (BS). MSs are responsible for collecting the data encrypted by SNs and forwarding it to BS; BS is responsible for decrypting and analyzing the collected data. During the data collection process, an MS can collect an SN's data only after being authenticated by the SN using the pre-distribution key information. But it cannot decrypt the collected data. In this model, the adversaries can induce a new type of false data injection attack. In the attack, the replicated MSs impersonate uncompromised SNs to send false data to BS by using the compromised key information. If BS accepts a large amount of false data, it will make a wrong judgment. Analysis and simulation show that the proposed model has excellent resistance against MS replication attacks and false data injection attacks by setting appropriate parameter values.

To achieve security in wireless sensor networks (WSNs), it is important to be able to encrypt messages sent among sensor nodes by using shared keys between them. Due to resource constraints, achieving such key agreement in WSNs is nontrivial. Previous research indicates that key management schemes using deployment knowledge can significantly improve the performance of WSNs. Nevertheless, in these schemes, resilient local connectivity and resilient global connectivity become unstable when deployment error changes. To resolve the above problem, in this article, a one-way associated key management model is proposed. In this model, the key pool consists of two layers: 1) the global layer and 2) the local layer. According to different deployment errors, the number of keys allocated from the global key pool and local key pools can be dynamically adjusted, thereby improving the stability of networks' performance. In multiphase sensor networks, analysis and simulation indicate that our scheme has better adaptability in applications where deployment error changes as compared with related schemes.

Unattended wireless sensor networks (UWSNs) are vulnerable to mobile sink (MS) replication attack. In this attack, using the compromised key information, an attacker can collect data from networks by impersonating sinks. To resist such an attack, some schemes have been proposed. To improve the resilience of MS replication attack of these schemes, we can integrate them with schemes based on deployment knowledge. However, there are the following defects: 1) the probability of mutual authentication between a MS and a sensor node is less than 1 and 2) during the authentication phase, the energy consumption of sensor nodes increases significantly as the deployment area expands. In this paper, we construct 3-D backward key chains based on deployment knowledge and propose a new authentication scheme based on these. As compared with these existing related schemes, the detailed theory analysis and simulation results indicate that the scheme can ensure that a MS can be authenticated by sensor nodes, and can improve the resilience of networks' MS replication attack with low energy consumption.