# Quantum one-time tables for unconditionally secure qubit-commitment

## TL;DR

This paper introduces quantum one-time tables (QOTT), a novel quantum correlation resource enabling unconditionally secure qubit-commitment, surpassing classical and entangled states in efficiency and security, with potential for universal composability.

## Contribution

It presents the first scheme for unconditionally secure qubit-commitment using quantum one-time tables, expanding quantum cryptography beyond key distribution.

## Key findings

- QOTT can enhance security with half the entropy cost compared to classical OTTs.
- The scheme is proven to be universally composable.
- Partially entangled mixed states are more valuable than maximally entangled states for this purpose.

## Abstract

The commodity-based cryptography is an alternative approach to realize conventionally impossible cryptographic primitives such as unconditionally secure bit-commitment by consuming pre-established correlation between distrustful participants. A unit of such classical correlation is known as the one-time table (OTT). In this paper, we introduce a new example besides quantum key distribution in which quantum correlation is useful for cryptography. We propose a scheme for unconditionally secure qubit-commitment, a quantum cryptographic primitive forbidden by the recently proven no-masking theorem in the standard model, based on the consumption of the quantum generalization of the OTT, the bipartite quantum state we named quantum one-time tables (QOTT). The construction of the QOTT is based on the newly analyzed internal structure of quantum masker and the quantum secret sharing schemes. Our qubit-commitment scheme is shown to be universally composable. We propose to measure the randomness cost of preparing a (Q)OTT in terms of its entropy, and show that the QOTT with superdense coding can increase the security level with half the cost of OTTs for unconditionally secure bit-commitment. The QOTT exemplifies an operational setting where neither maximally classically correlated state nor maximally entangled state, but rather a well-structured partially entangled mixed state is more valuable resource.