Secure interaction with piggybacked key-exchange

Online collaboration tools are a ubiquitous mediator of many human interactions. In the virtual world, they enable secure interaction by controlling access to shared resources. Yet relying on them to support face-to-face collaboration might be suboptimal as they require Internet connectivity. A more efficient way of co-located resource sharing is the use of local communications. Yet setting up the necessary security mechanisms can be cumbersome. In this article we present PIKE and its variant P2PIKE, key-exchange protocols that minimize this configuration effort. Both piggyback the exchange of keys on top of an existing service and exchange keys proactively—before the interaction takes place. In addition to an implementation, we outline two applications and present a thorough evaluation to show the benefits and limitations of our approach.