Symmetric Searchable Encryption with Sharing and Unsharing.

In this paper, we study Symmetric Searchable Encryption (SSE) in a multi-user setting in which each user dynamically shares its documents with selected other users, allowing sharees also to perform searches. We introduce the concept of a Symmetric Searchable Encryption with Sharing and Unsharing, an extension of Multi-Key Searchable Encryption (NSDI ’14), that supports dynamic sharing and unsharing of documents amongst users. We also strengthen the security notion by considering a simulation-based notion that does not restrict sharing between honest and compromised users.