Summary Low cost, decentralized architecture and ad hoc nature are a few desirable properties of wireless sensor networks that make them well suited for gathering sensitive information in hazardous deployment grounds. Existing security protocols exploit various cryptographic tools to strengthen their security. Not many works focus on constraints faced by an adversary. One such constraint being practical difficulties to trace a particular frequency band from a large range of unknown frequencies, specially in unharmonious geographical locations. Our research capitalizes on this weakness encountered by an adversary and preassigns nodes with multiple frequency bands from a wide range of frequencies allocated to the network. Deployed nodes can discover these bands during set network setup phase by a simple trick. Nodes are to internally switch their frequency bands depending on parametric variation that are caused by an (external) impulse. Experiments conducted using magneto optic sensors confirm that any variation of their parameter affects frequencies of emergent waves. Similar behavior is expected from application specific sensors. Frequency regulation (FR) concept is applied to combinatorial key predistribution schemes (KPS) having (regular) degreer. Depending onrand each node's capability to switch internal frequencies, nodes are preallocated withnfrequency bands. This naturally partitions the (distributed) network and results in improved resilience. Combining our FR concept to a KPS where the number of shared key between a pair of nodes is at most one (γ≤ 1) may yield best case scenario of an ideally resilient key predistribution. Our analysis of systems that combines FR idea with KPS whereγ > 1 leads to an optimized key‐band distribution argument and drastic resilience improvements. Results of simulations conducted assuming real‐life scenario ascertain our analysis and establishes superior performance of our protocols as compared to prominent ones.

Designing efficient key management schemes have been a long standing challenge in the literature of secure Wireless Sensor Networks (WSNs). Due to constraint in resources of the basic building blocks (nodes) of such networks, one opts for Key Predistribution Schemes (KPS) to preload and later establish the low cost symmetric cryptographic keys in the nodes. This paper analyzes several existing KPS and in the process highlights couple of pertinent weaknesses, viz. lack of direct full connectivity in certain KPS and overall lack of scalability in most existing schemes. As a result, a deterministic merging block technique is developed to fix the connectivity issue while an unique method based on localization scales any KPS in particular, the merged schemes. Critical study of various network parameter suggests that the resultant schemes perform better in terms of connectivity, scalability, resiliency, yet possess low and uniform key rings.

Key management, one of the most challenging problems in Wireless Sensor Network (WSN) has been efficiently addressed using Key Predistribution (KPD) schemes. This paper analyzes a localized KPD based on the Transversal Design (TD) design or Reed Solomon (RS) codes schemes; later two shown to be similar. They lack full direct communications among their constituent nodes and so, rely on multi-hop involving other nodes reducing the overall efficiency of the system. The communication issue for TD or RS and hence the localized KPD gets resolved by Deterministic Merging of exactly two nodes. The weakness of `selective node attack' of the merged designs, similar to their original KPDs, is overcome by invoking the novel trick of Sarkar \emph{et al.} Simulation results confirm that the various network parameters of the proposed schemes improves significantly over a random counterpart among other existing schemes.

Constraints in resources of the constituent sensors of any Wireless Sensor Network (WSN) are most challenging aspects while designing security models for such networks. Naturally one prefers 'less expensive' symmetric key cryptography over public key techniques during communication among nodes. In such cryptosystems, both the communicating parties must possess the same cryptographic key prior to message exchange. This is normally achieved by key predistribution (KPD). One such scheme based on Transversal Design was proposed by Lee and Stinson in 2005. However the mentioned scheme is devoid of full communication among the nodes. The aforesaid weakness gives rise to multi-hop communication involving other node(s) which reduces efficiency of such communication. Deterministic merging nodes results in a smaller network having bigger blocks result in full communication between the blocks. The deterministic merging block strategy can be thought as pre assigning deterministic paths for any pair of non communicating nodes of the original KPD which lags full communication.

In this paper, we suggest the idea of separately treating the connectivity and communication model of a Wireless Sensor Network (WSN). We then propose a novel connectivity model for a WSN using first order Reed-Muller Codes. While the model has a hierarchical structure, we have shown that it works equally well for a Distributed WSN. Though one can use any communication model, we prefer to use the communication model suggested by Ruj and Roy for all computations and results in our work. Two suitable secure (symmetric) cryptosystems can then be applied for the two different models, connectivity and communication respectively. By doing so we have shown how resiliency and scalability are appreciably improved as compared to Ruj and Roy.