Continuous-Variable Protocol for Oblivious Transfer in the Noisy-Storage Model

TL;DR

This paper introduces and experimentally demonstrates the first continuous-variable quantum oblivious transfer protocol, establishing security in the noisy-storage model using novel uncertainty relations for optical systems.

Contribution

It presents a new continuous-variable quantum oblivious transfer protocol and proves its security in the noisy-storage model, supported by experimental validation.

Findings

Successfully implemented the protocol with different channel losses

Demonstrated security based on new uncertainty relations for continuous variables

Enabled the use of continuous-variable systems for secure two-party cryptography

Abstract

Cryptographic protocols are the backbone of our information society. This includes two-party protocols which offer protection against distrustful players. Such protocols can be built from a basic primitive called oblivious transfer. We present and experimentally demonstrate here the first quantum protocol for oblivious transfer for optical continuous-variable systems, and prove its security in the noisy-storage model. This model allows to establish security by sending more quantum signals than an attacker can reliably store during the protocol. The security proof is based on new uncertainty relations which we derive for continuous-variable systems, that differ from the ones used in quantum key distribution. We experimentally demonstrate the proposed oblivious transfer protocol for various channel losses by using entangled two-mode squeezed states measured with balanced homodyne detection. Our work enables the implementation of arbitrary two-party quantum cryptographic protocols with continuous-variable communication systems.