A Protocol to Prevent Malicious Information Flow in P2PPS Systems

In the peer-to-peer (P2P) type of topic-based publish/subscribe (P2PPS) model, each peer process (peer) can publish and subscribe event messages which are characterized by topics with no centralized coordinator. A peer pj publishes an event message ej after receiving an event message ei, i.e. ei causally precedes ej. Here, the event message ej may carry information of the event message ei. If a peer pk receiving ej is not allowed to subscribe the topics of ei, the peer pk illegally obtains the information by receiving ej. In our previous studies, the SBS, TBS, and FS-H protocols are proposed to prevent illegal information flow. In addition, if a source peer pi publishes an event message e without giving related topics or with giving unrelated topics, a destination peer pj may misunderstand the meaning of the event message e. Here, malicious information flow occurs. In this paper, we newly propose a TBSM (topic-based synchronization to prevent malicious information flow) protocol. Here, event messages which may cause malicious information flow are banned. In the evaluation, we show the number of event messages banned in the TBSM protocol is larger than the TBS protocol since the number of event messages which are just malicious is larger than just illegal.