Defeating classical bit commitments with a quantum computer

TL;DR

This paper explores the limitations of classical bit commitments in the context of quantum computing, demonstrating that they cannot provide unconditional security against quantum adversaries.

Contribution

It proves that classical unconditionally concealing bit commitments are ineffective for quantum security, highlighting the fundamental differences between classical and quantum cryptographic protocols.

Findings

Classical bit commitments do not enhance security against quantum attacks.

Quantum computers can break classical bit commitment schemes.

Unconditionally secure bit commitments require quantum protocols.

Abstract

It has been recently shown by Mayers that no bit commitment scheme is secure if the participants have unlimited computational power and technology. However it was noticed that a secure protocol could be obtained by forcing the cheater to perform a measurement. Similar situations had been encountered previously in the design of Quantum Oblivious Transfer. The question is whether a classical bit commitment could be used for this specific purpose. We demonstrate that, surprisingly, classical unconditionally concealing bit commitments do not help.