量子计算具有并行计算能力，在解决某些特定问题上展现出超越经典计算的能力；一旦大型量子计算机研制成功，基 于计算复杂性假设的经典密码算法和协议，其安全性将受到严重挑战。量子密码是一种新型密码体制，相应安全性基于量子 力学原理，因能对抗量子计算的攻击而受到广泛关注。本文聚焦量子密码近40年的发展历程，梳理了量子密钥分配、量子 安全直接通信、量子秘密共享、量子身份认证、量子两方安全计算、量子保密查询等量子密码协议的研究进展和发展趋势， 凝练发展过程中面临的技术与应用问题。分析表明，当前量子密码协议研究处于“量子密钥分配协议遥遥领先、其他协议有 待突破”的不平衡状态，也是“其他协议难以突破”的瓶颈状态。着眼未来应用，针对数字签名、两方安全计算问题的实用 化量子协议是亟需解决的核心问题。为此建议，量子密码与后量子密码研究应同步开展，加强“量子科技”“密码学”学科 的交叉研究和人才培养，优化对相关基础研究的考核评价机制。

Quantum computing has the capability of parallel computing and is superior to classical computing in solving some specific problems. Once a large-scale quantum computer is developed, the security of classical cryptographic algorithms and protocols, which is based on the assumption of computational complexity, will be severely challenged. Quantum cryptography is a new cryptosystem; its security is based on the principles of quantum mechanics, and can resist the attack of quantum computing. This paper focuses on the nearly 40 years development of quantum cryptographic protocols, including quantum key distribution (QKD), quantum secure direct communication, quantum secret sharing, quantum identity authentication, two-party secure computation, and quantum private query, and summarizes the problems in the process of development. The analysis shows that the quantum cryptographic protocols are in an unbalanced state: QKD is far ahead of other protocols and other protocols are difficult to achieve breakthroughs. In the future, practical quantum protocols for digital signature and two-party secure computation are core issues that needs to be addressed urgently. Therefore, research on quantum and post-quantum cryptography should be conducted synchronously, cross-over study and talent cultivation for the quantum science and cryptography disciplines should be strengthened, and the examination and evaluation mechanism of relevant basic research needs to be optimized.