Enabling information confidentiality in publish/subscribe overlay services

Alice has a piece of valuable information which she is willing to sell to anyone who is interested in; she is too busy and wants to ask Bob, a professional broker, to sell that information for her; but Alice is in a dilemma where she cannot trust Bob with that information but Bob cannot help her find her customers without knowing that information. In this paper, we propose a security mechanism called information foiling to address new confidentiality problems arising in pub/sub overlay services [1]. Information foiling extends Rivest's "Chaffing and Winnowing" [2], and its basic idea is to carefully generate a set of fake messages to hide an authentic message. Information foiling requires no modification inside the broker network so that the routing/filtering capabilities of broker nodes remains intact. We formally present the information foiling mechanism in the context of publish/subscribe overlay services, and discuss its applicability in other Internet applications. For publish/subscribe applications, we propose a suite of optimal schemes for fake message generation in different scenarios. Real-world data are used in our evaluation to demonstrate the effectiveness of the proposed schemes.