A unified approach to combinatorial key predistribution schemes for sensor networks

There have been numerous recent proposals for key predistribution schemes for wireless sensor networks based on various types of combinatorial structures such as designs and codes. Many of these schemes have very similar properties and are analysed in a similar manner. We seek to provide a unified framework to study these kinds of schemes. To do so, we define a new, general class of designs, termed “partially balanced t-designs”, that is sufficiently general that it encompasses almost all of the designs that have been proposed for combinatorial key predistribution schemes. However, this new class of designs still has sufficient structure that we are able to derive general formulas for the metrics of the resulting key predistribution schemes. These metrics can be evaluated for a particular scheme simply by substituting appropriate parameters of the underlying combinatorial structure into our general formulas. We also compare various classes of schemes based on different designs, and point out that some existing proposed schemes are in fact identical, even though their descriptions may seem different. We believe that our general framework should facilitate the analysis of proposals for combinatorial key predistribution schemes and their comparison with existing schemes, and also allow researchers to easily evaluate which scheme or schemes present the best combination of performance metrics for a given application scenario

Deterministic Merging of Blocks in Combinatorial Design based Key Predistribution in Distributed Wireless Sensor Network

Sensor nodes have severe constraints in terms of its resources such as processing power, memory, communication range, battery power. Due to wireless nature of communication between nodes in a wireless sensor network, any attacker can intercept the communicating messages between sensor nodes. So the need for securing these messages is obvious. Due to resource constraints of sensor nodes, public key cryptography can’t be employed for securing the communication as public key cryptography demands much computational effort. So, private key cryptography is natural choice for securing the communication in wireless sensor network. Key predistribution has become obvious choice for distributing keys in sensor nodes for secured communication in a wireless sensor network. A pool of keys is first taken, and then a set of keys from this key pool is installed in every sensor node before their deployment. The keys predistributed to a particular sensor node can be drawn from the key pool probabilistically or deterministically. Combinatorial design which was originated as a branch of statistics and later found its vast application in coding theory and of late in cryptography plays a vital role in deterministic key predistribution. The connectivity and resiliency offered by some combinatorial design based key predistribution schemes can be sometimes offered by merging of blocks and then assign these merged blocks to sensor nodes. The question is how to choose blocks for merging? There is a prior general work on merging of blocks which has been studied on transversal design based key predistribution scheme. This approach is not deterministic, but heuristic. A deterministic algorithm for merging of blocks has been proposed. The orthogonal array based key predistribution scheme has been studied in detail and the non suitability of merging approach to improve its performance has been shown. In addition, a key establishment algorithm for transversal design based key predistribution scheme has been proposed

Key Predistribution Schemes in Distributed Wireless Sensor Network using Combinatorial Designs Revisited

A Sensor Node in Wireless Sensor Network has very limited resources such as processing capability, memory capacity, battery power, and communication capability. When the communication between any two sensor nodes are required to be secured, the symmetric key cryptography technique is used for its advantage over public key cryptography in terms of requirement of less resources. Keys are pre-distributed to each sensor node from a set of keys called key pool before deployment of sensors nodes. Combinatorial design helps in a great way to determine the way keys are drawn from the key pool for distributing to individual sensor nodes. We study various deterministic key predistribution techniques that are based on combinatorial design

Broadcast-enhanced key predistribution schemes

We present a formalisation of a category of schemes that we refer to as broadcast-enhanced key predistribution schemes (BEKPSs). These schemes are suitable for networks with access to a trusted base station and an authenticated broadcast channel. We demonstrate that the access to these extra resources allows for the creation of BEKPSs with advantages over key predistribution schemes such as flexibility and more efficient revocation. There are many possible ways to implement BEKPSs, and we propose a framework for describing and analysing them. In their paper “From Key Predistribution to Key Redistribution,” Cichoń et al. [2010] propose a scheme for “redistributing” keys to a wireless sensor network using a broadcast channel after an initial key predistribution. We classify this as a BEKPS and analyse it in that context. We provide simpler proofs of some results from their paper, give a precise analysis of the resilience of their scheme, and discuss possible modifications. We then study two scenarios where BEKPSs may be particularly desirable and propose a suitable family of BEKPSs for each case. We demonstrate that they are practical and efficient to implement, and our analysis shows their effectiveness in achieving suitable trade-offs between the conflicting priorities in resource-constrained networks

A Deterministic Approach of Merging of Blocks in Transversal Design based Key Predistribution

Transversal Design is a well known combinatorial design that has been used in deterministic key predistribution scheme. Merging of blocks in a design sometimes helps to obtain a key predistribution scheme with better performance. A deterministic merging strategy to merge the blocks has been discussed. Also, a simple key establishment method for transversal design based key predistribution scheme has been discussed

Comments on a sensor network key redistribution technique of Cichon, Golebiewski and Kutylowski

Cichon, Golebiewski and Kutylowski (\cite{CGK}) proposed a technique for ``key redistribution\u27\u27 in sensor networks. The idea is that long-term keys held by the sensor nodes are used to encrypt temporal keys that a base station then broadcasts to the network. The temporal keys are used as session keys by the nodes in the sensor network. It is argued that this provides increased connectivity and resilience as compared to a standard Eschenauer-Gligor key predistribution scheme, as well as providing some additional advantages. In this paper, we provide some simpler proofs of some results from \cite{CGK}. As well, we give a precise analysis of the resilience of Cichon, Golebiewski and Kutylowski\u27s scheme, and we discuss modifications of the scheme based on defining a suitable intersection threshold