Advances in lightweight, small-sized and low-power sensors led to the development of wearable biosensors, and thus, to the accurate monitoring of human periphery. On top of this, pervasive computing has been improved and technologies have been matured enough to build plug-and-play body area networks (BANs). In a BAN, the main functionality of a node is to effectively and efficiently collect data from vital body parts, share it with the neighbors and make decisions accordingly. Because of the fact that the captured phenomenon is highly sensitive to privacy breaches in addition to being transmitted using the wireless communication medium, BANs require a security infrastructure. However, due to the extreme energy scarcity, bandwidth and storage constraints of the nodes, conventional solutions are inapplicable. In this survey, we present an overview of BANs and provide a detailed investigation into the developed security infrastructures. We examined the literature and combined the corresponding proposals under two major classes: (i) pure-cryptographic security mechanisms and (ii) bio-cryptographic security mechanisms. Pure-cryptographic methods include constructions based on the well-known symmetric or asymmetric cryptography primitives and they are suitable for securing the communication between any two network entities. On the other hand, bio-cryptographic methods benefit from the network's context-awareness and to the best of our knowledge, they have been utilized only for the communication among the biosensors.
