A novel and scalable key management scheme for wireless sensor networks

Due to the sensitive nature of the data gathered by many wireless sensor networks (WSNs) it is becoming critical that this data be protected. However, due to the constrained nature of the resources available on sensor nodes, traditional wireless networking security solutions are not viable because of their processing and memory requirements, power consumption, speed and communications overhead. In particular, the use of asymmetric cryptographic operations, i.e. public key ciphers, often places an unjustifiable burden on a sensor node's resources. As a result symmetric key ciphers are primarily used in WSNs. This, however, introduces the difficult task of how to deploy and manage the required symmetric keys, which can be a major challenge, even for moderately sized networks. All currently available solutions to this problem either have a very simple keying model for the network, resulting in a low level of security overall, or else are so complicated that they take up an inordinate amount of code memory. Additionally application developers tend not to understand these complicated solutions, both in terms of need and execution, and so they are not used. We present a key management solution that overcomes these problems by exploiting a feature found on many new generation sensor nodes, this feature being the availability of very large amounts of non-volatile memory, usually in the form of micro or mini SD card support.