On the privacy protection in publish/subscribe systems

In a publish/subscribe (pub/sub) system, information (referred to as events) published by publishers and interests submitted by subscribers are sent to the network, which conducts matching between events and interests, and only delivers those events satisfying the interests. When the pub/sub infrastructure is untrusted, it is often desirable to keep both events and interests secret from the pub/sub network. In this paper, we formulate this goal as the private subscription problem. We then describe cryptographic schemes to solve this problem in some types of publish/subscribe systems. The algorithms we present are efficient in that they are based on symmetric encryptions requiring O(n) cipher operations for a message of length n.