A Highly Scalable Key Pre-Distribution Scheme for Wireless Sensor Networks

A Highly Scalable Key Pre-Distribution Scheme for Wireless Sensor Networks


Given the sensitivity of the potential WSN applications and because of resource limitations, key management emerges as a challenging issue for WSNs. One of the main concerns when designing a key management scheme is the network scalability. Indeed, the protocol should support a large number of nodes to enable a large scale deployment of the network. In this paper, we propose a new scalable key management scheme for WSNs which provides a good secure connectivity coverage. For this purpose, we make use of the unital design theory. We show that the basic mapping from unitals to key pre-distribution allows us to achieve high network scalability. Nonetheless, this naive mapping does not guarantee a high key sharing probability. Therefore, we propose an enhanced unital-based key pre-distribution scheme providing high network scalability and good key sharing probability approximately lower bounded by 1 e  0.632. We conduct approximate analysis and simulations and compare our solution to those of existing methods for different criteria such as storage overhead, network scalability, network connectivity, average secure path length and network resiliency. Our results show that the proposed approach enhances the network scalability while providing high secure connectivity coverage and overall improved performance. Moreover, for an equal network size, our solution reduces significantly the storage overhead compared to those of existing solutions.

PROJECT OUTPUT VIDEO: (Click the below link to see the project output video):


Wireless sensor networks (WSNs) are increasingly used in critical applications within several fields including military, medical and industrial sectors. Given the sensitivity of these applications, sophisticated security services are required. Key management is a corner stone for many security services such as confidentiality and authentication which are required to secure communications in WSNs. The establishment of secure links between nodes is then a challenging problem in WSNs. Because of resource limitations, symmetric key establishment is one of the most suitable paradigms for securing exchanges in WSNs. On the other hand, because of the lack of infrastructure in WSNs, we have usually no trusted third party which can attribute pair wise secret keys to neighboring nodes, that is why most existing solutions are based on key pre-distribution.


A host of research work dealt with symmetric key pre-distribution issue for WSNs and many solutions have been proposed In the existing system many disadvantages occur: the design of key rings (blocks of keys) is strongly related to the network size, these solutions either suffer from low scalability (number of supported nodes), or degrade other performance metrics including secure connectivity, storage overhead and resiliency in the case of large networks.


In this proposed system, our aim is to tackle the scalability issue without degrading the other network performance metrics. For this purpose, we target the design of a scheme which ensures a good secure coverage of large scale networks with a low key storage overhead and a good network resiliency. To this end, we make use, of the unital design theory for efficient WSN key pre-distribution.


The advantages of the proposed system as follows:

  • We propose a naive mapping from unital design to key pre-distribution and we show through analytical analysis that it allows to achieve high scalability.
  • We propose an enhanced unitalbased key pre-distribution scheme that maintains a good key sharing probability while enhancing the network scalability.
  • We analyze and compare our new approach against main existing schemes, with respect to different criteria: storage overhead, energy consumption, network scalability, secure connectivity coverage, average secure path length and network resiliency.




  1. Node Deployment
  2. Key Generation
  3. Key Pre-distribution Technique
  4. Secure Transmission with Energy


Node Deployment

The first module is Node deployment, where the node can be deployed by specifying the number of nodes in the network. After specifying the number of nodes in the network, the nodes are deployed. The nodes are deployed with unique ID (Identity) number so that each can be differentiated. And also nodes are deployed with their energy levels.

Key Generation

After the Node deployment module, the key generation module is developed. Where the number of nodes and number of blocks should be specified, so that the key will be generated. The key is symmetric key and the key is displayed in the text area given in the node.

 Key Pre-distribution Technique:

In this module, we generate blocks of m order initial design, where each block corresponds to a key set. We pre-load then each node with t completely disjoint blocks where t is a protocol parameter that we will discuss later in this section. In lemma 1, we demonstrate the condition of existence of such t completely disjoint blocks among the unital blocks. In the basic approach each node is pre-loaded with only one unital block and we proved that each two nodes share at most one key. Contrary to this, pre-loading each two nodes with t disjoint unital blocks means that each two nodes share between zero and keys since each two unitals blocks share at most one element. After the deployment step, each two neighbors exchange the identifiers of their keys in order to determine the common keys. This approach enhances the network resiliency since the attackers have to compromise more overlap keys to break a secure link. Otherwise, when neighbors do not share any key, they should find a secure path composed of successive secure links.

Secure Transmission with Energy

In this module, the node distance is configured and then the nodes with their neighbor information are displayed. So the nodes which is near by the node, is selected and the energy level is first calculated to verify the secure transmission. After that the data is uploaded and sent to the destination node. Where in the destination node, the key is verified and then the data is received.



  • Processor             –        Pentium –IV
  • Speed –     1 Ghz
  • RAM –     256 MB(min)
  • Hard Disk –      20 GB
  • Key Board –     Standard Windows Keyboard
  • Mouse –     Two or Three Button Mouse
  • Monitor –     SVGA


  • Operating System : Windows XP
  • Programming Language : NS2
  • Tool : CYGWIN


Walid Bechkit, Yacine Challal, Abdelmadjid Bouabdallah, and Vahid Tarokh-“ A Highly Scalable Key Pre-Distribution Scheme for Wireless Sensor Networks”- IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 12, NO. 2, FEBRUARY 2013.

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