Private searching on streaming data

Abstract

Private searching on streaming data is a process to dispatch to a public server a program, which searches streaming sources of data without revealing searching criteria and then sends back a buffer containing the findings. From an Abelian group homomorphic encryption, the searching criteria can be constructed by only simple combinations of keywords, e.g., disjunction of keywords. The recent breakthrough in fully homomorphic encryption has allowed one to construct arbitrary searching criteria theoretically. In this chapter, we consider a new private query suggested by Yi et al. [23], which searches for documents from streaming data on the basis of keyword frequency, such that the frequency of a keyword is required to be higher or lower than a given threshold. This form of query can help us in finding more relevant documents. Based on the state-of-the-art fully homomorphic encryption techniques, we describe disjunctive, conjunctive, and complement constructions for private threshold queries based on keyword frequency given by Yi et al. [23]. Combining the basic constructions, we also describe their generic construction for arbitrary private threshold queries based on keyword frequency.