Updating Distributed Cache Mechanism using Bloom Filter for Asymmetric Cryptography in Large Wireless Networks

Objectives: Public key cryptography helps in achieving information security in wireless networks. Public key will be issued by CA (Certificate Authority). But having CA in wireless network makes it vulnerable to various attacks. Hence distributed cache was proposed where each node in network caches public key of some nodes existing in network in its cache and request to obtain keys not cached will be made via trusted nodes. Due to limited memory only few keys can be cached. There exists an optimal threshold value for caching keys so that equal number of both local nodes and remote nodes public keys can be cached. Methods: Random replacement policy was used for updating cache contents, where if a node’s local/ remote key cached ratio exceeds optimal ratio then a key will be randomly chosen from the cache and will be removed. Here we propose implementation of bloom filter in cache to cache public key of nodes existing in network. Findings: By using bloom filter of large size, more number of public keys can be cached thereby providing space and time advantage and reduces query cost with increased usage of memory. MAC (Media Access Control) id and PSN (Processor Serial Number) are used for uniquely identifying each node in network and are stored in encrypted format. When mismatch is found in encrypted MAC id and PSN, then that node is determined to be malicious node and its id will be notified to all nodes in network thus excluding the node from making any communication to other nodes in the network. Applications: Used for checking an element’s presence in the set thus reducing I/O lookup when large data set is used. Used as an alternative to cache as it uses limited memory more efficiently than cache does.