Semi-quantum communication, a model introduced by Boyer et al. (Phys Rev Lett 99:140501, 2007), involves the use of fully quantum users and semi-quantum, or “classical” users. These restricted users are only allowed to interact with the quantum channel in a limited manner. Originally introduced to study the key-distribution problem, semi-quantum research has since expanded, and continues to grow, with new protocols, security proof methods, experimental implementations, and new cryptographic applications beyond key distribution. Research in the field of semi-quantum cryptography requires new insights into working with restricted protocols and, so, the tools and techniques derived in this field can translate to results in broader quantum information science. Furthermore, other questions such as the connection between quantum and classical processing, including how classical information processing can be used to counteract a quantum deficiency in a protocol, can shed light on important theoretical questions. This work surveys the history and current state of the art in semi-quantum research. We discuss the model and several protocols offering the reader insight into how protocols are constructed in this realm. We discuss security proof methods and how classical post-processing can be used to counteract users’ inability to perform certain quantum operations. Moving beyond key distribution, we survey current work in other semi-quantum cryptographic protocols and current trends. We also survey recent work done in attempting to construct practical semi-quantum systems including recent experimental results in this field. Finally, as this is still a growing field, we highlight, throughout this survey, several open problems that we feel are important to investigate in the hopes that this will spur even more research in this topic.

Semi-quantum cryptography

https://iopscience.iop.org/article/10.1088/1674-1056/abaedd/pdf

New semi-quantum key agreement protocol based on high-dimensional single-particle states

A semi-quantum key agreement protocol is proposed to allow one quantum participant and two classical ones to negotiate the final shared secret key equally. The protocol employs the four-particle cluster state, whose large persistency of entanglement could ensure the feasibility and the security of the protocol. The security of the proposed semi-quantum key agreement protocol against various attacks including the external eavesdropper’s attacks and the participant’s attacks is discussed. Furthermore, in comparison with the previous quantum key agreement and semi-quantum key agreement protocols, the proposed semi-quantum key agreement protocol contains more classical parties, requires less quantum channels, and needs no external assistance.

Three-Party Semi-Quantum Key Agreement Protocol

A semiquantum key distribution (SQKD) protocol allows two users, one of whom is restricted in their quantum capabilities to being nearly classical, to establish a shared secret key, secure against an all-powerful adversary. The study of such protocols helps to answer the fundamental question of “how quantum” must a protocol be to gain an advantage over classical communication. In this article, we design a new SQKD protocol using high-dimensional quantum states and conduct an information theoretic security analysis. We show that, similar to the fully quantum key distribution case, high-dimensional systems can increase the noise tolerance in the semiquantum case. Furthermore, we prove several general security results which are applicable to other (S)QKD protocols (both high-dimensional ones and standard qubit-based protocols) utilizing a two-way quantum channel.

/pdf/high-dimensional-semiquantum-cryptography-z8x8ihqq98.pdf

High-Dimensional Semiquantum Cryptography

In this paper, we present a novel quantum authentication protocol based on entanglement swapping of Bell states, in which it can ensure two users to simultaneously authenticate each other. With the help of a semi-honest third party, our protocol can realize mutual identity authentication by utilizing Bell states and applying Pauli operators. In addition, this protocol can prevent the third party from knowing the secret key shared in prior between the two users. Finally, the analysis results show that this protocol is secure and efficient.

A novel quantum identity authentication based on Bell states

To ensure communication security, it is necessary to verify the identities of the communicators. Two semi-quantum identification protocols with single photons involving two parties, i.e., quantum Alice and classical Bob, are presented. In the first semi-quantum identification protocol, classical Bob can authenticate quantum Alice’s identity without the help of an authenticated classical channel. As for the second one, quantum Alice can verify the identity of classical Bob without the classical measurement ability. Semi-quantum identification is significant to ensure the security of semi-quantum key distribution, semi-quantum secret sharing and so on. The proposed two identification protocols against common attacks can be employed in several existing semi-quantum key distribution protocols based on single photons to resist the man-in-the-middle attack.

Wei Bi

Papers

Semi-quantum identification