A-CACHE: An anchor-based public key caching scheme in large wireless networks

When asymmetric cryptography is used in wireless networks, public keys of the nodes need to be made available securely. In other networks, these public keys would have been certified by a certificate authority (CA). However, the existence of a single CA in large wireless networks such as mobile ad hoc networks and wireless sensor networks can lead to a communication hotspot problem and become an easy target for attacks. In this work, we propose a distributed technique, termed A-CACHE, to cache the public keys on regular nodes. One salient feature of our scheme is that some anchor nodes with larger cache memories are exploited. Due to the limited memory size that each node is allowed to dedicate for key caching, only a limited number of keys will be cached. Access to the public keys of other nodes is possible based on a chain of trust. In addition, multiple copies of public keys from different chains of trusted nodes provide fault-tolerant protections and guard against malicious attacks. We explain our technique in detail and investigate its prominent features in this work. Through analysis and evaluations, we observe the existence of an optimum ratio to cache the keys of local nodes. © 2015 Elsevier B.V. All rights reserved.