Paper 2020/1488

General Properties of Quantum Bit Commitments

Jun Yan

Abstract

The concept of quantum bit commitment was introduced more than three decades ago in a failed attempt to base unconditionally secure bit commitment solely on laws of quantum mechanics. In this work, we explore general properties of conditional quantum bit commitments that additionally rely on quantum computational hardness but without any mathematical structures, e.g. quantum-secure one-way functions. While in general quantum bit commitment can only guarantee a fairly weak binding property compared with its classical counterpart, we discover that it enjoys some other nice properties that classical bit commitment does not have. In particular, among others, it turns out that any interactive quantum bit commitment scheme can be compiled into a non-interactive one. These properties not only enable us to simplify both the construction and the security analysis of quantum bit commitment schemes significantly but also suggest a potential use of quantum bit commitments as a replacement of classical ones in quantum cryptography.