A group-based multilayer encryption scheme for secure dissemination of post-disaster situational data using peer-to-peer delay tolerant network

In the event of a disaster, the communication infrastructure can be partially or totally destroyed, or rendered unavailable due to high congestion. Today´s smart-phones that can communicate directly via Bluetooth or WiFi without using any network infrastructure, can be used to create an opportunistic post disaster communication network where situational data can spread quickly, even in the harshest conditions. However, presence of malicious and unscrupulous entities that forward sensitive situational data in such a network may pose serious threats on accuracy and timeliness of the data. Therefore, providing basic security features, like authentication, confidentiality and integrity, to all communications occurring in this network becomes inevitable. But, in such an opportunistic network, that uses short range and sporadic wireless connections, no trusted third party can be used as it won´t be accessible locally at the runtime. As a result, traditional security services like cryptographic signatures, certificates, authentication protocols and end-to-end encryption become inapplicable. Moreover, since disaster management is generally a group based activity; a forwarding entity may be better authenticated based on its group membership verification. In this paper, we propose a Group-based Distributed Authentication Mechanism that enables nodes to mutually authenticate each other as members of valid groups and also suggest a Multilayer Hashed Encryption Scheme in which rescue-groups collaboratively contribute towards preserving the confidentiality and integrity of sensitive situational information. The schemes provide authentication, confidentiality and integrity in a fully decentralized manner to suit the requirements of an opportunistic post disaster communication network. We emulate a post disaster scenario in the ONE simulator to show the effectiveness of our schemes in terms of delivery ratio, average delay and overhead ratio.