An information-theoretically secure quantum multiparty private set intersection

In the current age of increasing data, Private Set Intersection (PSI) is one of the most prominent and important cryptographic building block. It enables two organizations to determine the intersection of their input sets in such a way that no other information is leaked. In real life, there are situations where more than two parties desire to compute the intersection of their private sets. Herein, we propose a generalized version of PSI, called Multi-party private set intersection (MPSI), where number of involved parties is not restricted to two. Nearly all of the existing MPSI protocols are relying on the hardness problems like integer factorization and discrete logarithm. However, these hard problems are unable to withstand the threat possessed by large scale quantum computers. Thus, there is a need of MPSI protocols which are secure from the quantum attacks and also provide long-term security. Quantum cryptography (QC) is one such tool that addresses this issue. In this work, we develop the first MPSI based on QC. The scheme put-forwarded by us attains long-term security and remains secure against quantum attacks.