Dynamic Secret Sharing in Wireless Network for Security Purposes

Abstract

Wireless networks are widely accepted in almost all fields of life. Due to the broadcast nature, extensive and across-the-board use of these networks, security is becoming a critical issue day by day in these networks. Present security measures are based on two popular encryption algorithms, Diffie-Hellman Key Exchange (DH) and RSA (the name given after its inventors Rivest-Shamir-Adleman). Public Key Infrastructure (PKI) is based on these algorithms, and these are just computationally secure. DH is vulnerable to Man In The Middle attack (MITM). Computationally secure means, with large enough computational resources DH and RSA can be breached theoretically. But, presently these resources do not exist. Short size RSA keys such as 1024-bit can be breached, but present internet applications are using 2048-bit keys that are hard to breach with existing resource until quantum computing becomes a reality. The adhoc networks are widely exercised in defense, military, disaster, and mission critical applications for pairwise as well as for group communication. Multi-party secret key establishment in low-resource networks including 802.11ah, 802.11ba (low-power WiFi), Zigbee, Bluetooth Low-Energy (BLE), and Wireless Body Area Networks (WBANs) requires fast attention of security experts. That’s why, the focus of our study has been set to provide an economical and cost effective multi-party secret key generation solution for resource-constrained adhoc setups. In our study, the results are obtained from the experiments and tests that used real IEEE 802.11 adapters. These tests, experiments and the analysis of obtained results prove this study a groundbreaking attempt towards multi-party secret key generation in the perspectives of limited storage, bandwidth, and computational resources. To address these issues, probabilistic data structures called Bloom filters have been used in this study. Bloom filters are bit-array data structures. They occupy a very small space of memory to accommodate a large number of data elements regardless of their sizes. Because they are space efficient, that’s why, the WiFi nodes in our proposed approach have used Bloom filters of a few kilo bytes for sharing the information about large numbers of frames sniffed in monitor mode. The Bloom filters are irreversible data structures. In our proposed approach, WiFi nodes with the help of these data structures exchanged i the information of their frames secretly without exchanging the actual contents of the frames. Because they are irreversible, that is why no one can extract the actual contents of the frames from them. Thus, the use of Bloom filters in our proposed scheme brings about a novelty in the process of symmetric secret key acquisition in the sense that nodes agreed upon a common secret without exchanging the actual contents of sniffed frames. Since Bloom filters consume a small amount of memory and are bit array type of data structures, that’s why they are fast to process. These space/time efficiency features make them highly suitable for low-resource scenarios. The time and space complexities of our proposed secret key generation scheme are O(log(N)) and O(L) respectively. N is the number of frames and L is the length of the Bloom filter. Our proposed approach does not depend on mathematical relationships, conditions and computations; rather it uses the wireless natural phenomenon of frame losses, hashes and symmetric cryptography. Moreover, the frame losses at an attacker and at the legitimate nodes are independent of each other. Because our study based on the natural phenomenon of frame losses, hashes and symmetric cryptography, that’s why it is resilient against future quantum attacks. In this research, the use of real IEEE 802.11 WiFi adapters and the outcome of different experiments and their in-depth analysis confirm the practicality of this work in 802.11 and similar types of wireless adhoc networks.