# A Framework for Constructing a Secure Domain of Sensor Nodes
## 2 Related Works
In the proposed key management technique, symmetric and asymmetric key primitives are used at different levels of the hierarchy of sensor nodes. When applying the identity-based key management technique at the cluster head level, this solution consumes significantly more computational resources. The resource requirements of the pairing algorithm when implemented on the advanced RISC machine (ARM) processor using pairing functions were studied in Reference [8]. In Reference [9], the TinyPBC algorithm, which provides identity-based key management without interaction between participating nodes, was studied. In Reference [10], a novel key management protocol (KMP), which integrates implicit certificates with the standard elliptic curve Diffie-Hellman exchange and performs authentication and key derivation, was presented. Although the proposed KMP guarantees maximal airtime savings concerning conventional approaches, robust key negotiation, and efficient protection against replay attacks, the airtime consumption requirement for the exchange of multiple messages and certificates remains significant. This causes major consequences due to the significant latency in the authentication protocol when running over a typical low-rate communication channel and the considerable power consumption. In Reference [11], a cryptographic key management protocol based on the Identity-Based Symmetric Keying (IBSK) scheme was proposed. This protocol uses only two symmetric keys pre-deployed at each sensor and supports the ejection of the compromised nodes. Although the energy consumption overhead introduced by this key management scheme is remarkably low, this protocol is only suitable for network architectures in which only sensor-to-gateway secure sessions are allowed. In Reference [13], a procedure using asymmetric and symmetric cryptography that reduces the memory requirement was proposed. The efficient Quantis Random Number Generator is used to provide symmetric keys with full entropy. The method of delivering symmetric keys (so-called session keys) to nodes wishing to implement a safety data exchange is presented. A novel approach that was developed to provide secure group communication specifically to support dismounted warfighters at the tactical edge was presented in Reference [14]. The protocol supports a variety of requirements such as dynamic authorization and de-authorization of clients. This paper proposed a novel and secure key rotation mechanism based on multicast key dissemination for tackling the distribution of group encryption key updates at the tactical edge. Another issue is related to the security of the IoT for critical applications, since ensuring system security is a necessity to gain trust. Usually, the Certification Authority (CA) is used as the third party of trust. Unfortunately, for IoT network nodes, due to the limited resources of these nodes and the scalability problems, it is challenging to develop effective procedures for CA utilization. For this reason, IoT nodes should rather be organized as separate groups (clusters) of cooperating nodes. A separate security system (the secure domain of sensors) should be built in each cluster. In such a cluster, trust structures should be created locally. To build a local trust structure in each safe domain of sensors, a Trusted Platform Module (TPM) can be used. This should be a necessary component of every node included in the safe domain of sensors [15; 16; 17]. This approach also requires the development of procedures for building trust between cooperating clusters. The first implementation of the secure domain of sensor nodes, using our idea, was presented in Reference [15]. In this solution, each sensor node uses asymmetric cryptography supported by the TPM module to protect transmission and to protect the stored data in the resources of the sensor nodes and the authentication procedures. The result of using asymmetric cryptography was a large limitation of the domain size.