Quantum Search on Encrypted Data Based on Quantum Homomorphic Encryption

TL;DR

This paper introduces a quantum homomorphic encryption-based protocol enabling secure search on encrypted data by a quantum server, with efficient key management and perfect security for Clifford circuits.

Contribution

It presents a novel quantum homomorphic search protocol allowing secure, delegated search on encrypted data with minimal client-side quantum capabilities and a secure evaluation protocol for Clifford circuits.

Findings

Secure quantum search protocol with linear client decryption time

Trusted key center simplifies key update process

Perfect security for Clifford circuit evaluation

Abstract

We propose a homomorphic search protocol based on quantum homomorphic encryption, in which a client Alice with limited quantum ability can give her encrypted data to a powerful but untrusted quantum server and let the server search for her without decryption. By outsourcing the interactive key-update process to a trusted key center, Alice only needs to prepare and encrypt her original data and to decrypt the ciphered search result in linear time. Besides, we also present a compact and perfectly secure quantum homomorphic evaluation protocol for Cliford circuits, where the decryption key can be calculated by Alice with polynomial overhead with respect to the key length.