It is challenging to secure a wireless sensor network (WSN) because its inexpensive, tiny sensor nodes do not have the necessary processing capability, memory capacity, and battery life to take advantage of the existing security solutions for traditional networks. Existing security solutions for wireless sensor networks are mostly based on symmetric key cryptography with the assumption that sensor nodes are embedded with secret, temporary startup keys before deployment thus avoiding any use of computationally demanding public key algorithms altogether. However, symmetric key cryptography alone cannot satisfactorily provide all security needs for wireless sensor networks. It is still problematic to replenish an operational wireless sensor network with new sensor nodes securely. Current research on public key cryptography for WSNs shows some promising results, particularly in the use of elliptic curve cryptography and identity based encryption for WSNs. Although security is essential for WSNs, it can complicate some crucial operations of a WSN like data aggregation or in-network data processing that can be affected by a particular security protocol. Accordingly, in this chapter, the authors summarize, discuss, and evaluate recent symmetric key based results reported in literature on sensor network security protocols such as for key establishment, random key pre-distribution, data confidentiality, data integrity, and broadcast authentication as well as expose limitations and issues related to those solutions for WSNs. The authors also present significant advancement in public key cryptography for WSNs with promising results from elliptic curve cryptography and identity based encryption as well as their limitations for WSNs. In addition,they also discuss recently identified threats and their corresponding countermeasures in WSNs.
Survey on Asymmetric Key Cryptographic Algorithms
