Paper 2020/1488

General Properties of Quantum Bit Commitment

Jun Yan

Abstract

The concept of quantum bit commitment was introduced more than three decades ago in a failed attempt to base unconditional bit commitment solely on quantum information theory. In this work, we explore general properties of \textit{conditional} quantum bit commitment, which additionally assumes quantum computational hardness but without any mathematical structure (e.g. quantum-secure one-way function). While it is well known that a general quantum bit commitment scheme can only guarantee a fairly weak binding property compared with its classical counterpart, interestingly, we show that it also enjoys some other nice properties that its classical counterpart does not have. Among others, we show that any (interactive) quantum bit commitment scheme can be compiled into a non-interactive generic form (by an ensemble of quantum circuit pair). These general properties not only enable us to simplify both the construction and the security analysis of quantum bit commitment significantly but also suggest a potential use of it as a replacement of the classical one in quantum cryptography.