In this work, we construct Circuit-PSI protocols with linear computational and communication cost. Further, our protocols are concretely more efficient than $\mathsf{PSTY}$ -- we are $\approx 2.3\times$ more communication efficient and are up to $2.8\times$ faster in LAN and WAN network settings. We obtain our improvements through a new primitive called Relaxed Batch Oblivious Programmable Pseudorandom Functions ($\mathsf{RB\text{-}OPPRF}$) that can be seen as a strict generalization of Batch $\mathsf{OPPRF}$s in $\mathsf{PSTY}$. While using Batch $\mathsf{OPPRF}$s, in the context of Circuit-PSI results, in protocols with super-linear computational complexity, we construct $\mathsf{RB\text{-}OPPRF}$s that can be used to build linear cost and concretely efficient Circuit-PSI protocols. We believe that the $\mathsf{RB\text{-}OPPRF}$ primitive could be of independent interest. As another contribution, we provide more communication efficient protocols (than prior works) for the task of private set membership -- a primitive used in many PSI protocols including ours.
Category / Keywords: cryptographic protocols / Private Set Intersection, Secure Computation Date: received 9 Jan 2021 Contact author: nichandr at microsoft com,divya gupta@microsoft com,t-akshah@microsoft com Available format(s): PDF | BibTeX Citation Version: 20210112:075748 (All versions of this report) Short URL: ia.cr/2021/034