Multi-party encryption (MPE): secure communications in delay tolerant networks

Mobile ad hoc networks are a subset of delay tolerant networks (DTNs) composed of several mobile devices. These dynamic environments make conventional security algorithms unreliable; nodes located far apart from each other may not have access (available) to each other’s public keys or have doubt on the validity of public-keys, making secure message exchange difficult. Furthermore, ad hoc networks are likely to be highly compromised and therefore may be untrusted. Other security methods, such as identity-based encryption and Kerberos, rely on requesting key data from a trusted third party, which can be unavailable or compromised in a DTN like environment. The purpose of this paper is to introduce two security overlay networks capable of delivering messages securely, preventing both eavesdropping and alteration of messages. The first algorithm, Chaining, uses multiple midpoints to re-encrypt the message for the destination node. The second, Fragmenting, separates the message key into pieces that are routed and secured independently from each other. Both techniques improve security in hostile environments; under test conditions, Chaining reduces the number of messages intercepted by 90 %, and Fragmenting by 83 %. This improvement has a performance trade-off, however, reducing the delivery ratio by 63 % in both algorithms.