Secure Information Forwarding through Fragmentation in Delay-tolerant Networks

In application environments like international military coalitions or multi-party relief work in a disaster zone, passing secure messages using Delay Tolerant Networks (DTNs) is challenging because existing public-private key cryptographic approaches may not be always accessible across different groups due to the unavailability of Public Key Infrastructure (PKI). In addition, connectivity may be intermittent so finding the reliable route is also difficult. Thus, instead of sending the complete message in a single packet, fragmenting the messages and sending them via multiple nodes can help achieve better security and reliability when multiple groups are involved. Therefore, encrypting messages before fragmentation and then sending both the data fragments and the key fragments (needed for decryption) provide much higher security. Keys are also fragmented as sending the key in a single packet can hamper security if it is forwarded to some corrupted nodes who may try to tamper or drop it. Hence, in this paper, we develop a scheme to provide improved security by generating multiple key-shares and data fragments and disseminating them via some intermediate nodes. In this fragmentation process, we also create a few redundant blocks to guarantee higher data arrival rate at the destination when message drop rate is higher like in the DTN environment. Our performance evaluation when compared to the most closely related scheme like Multiparty Encryption shows the improvement on minimizing the number of compromised messages as well as reduced bandwidth consumption in the network.