4
1 Introduction
We then describe the functioning of a generic CKA protocol and prove its security.
Finally we describe the first experimental implementations of CKA protocols.
• In Chap. 5 we draw attention to the security threats posed by performing QKD with
imperfect quantum devices and discuss the solutions proposed so far. Specifically,
we present the decoy-state method to deal with sources emitting multiple photons.
We also introduce the concept of measurement-device-independent QKD, whose
security is independent of the trustworthiness of the measurement devices.
• The subject of Chap. 6 is the novel TF-QKD protocol, which applies the solutions
to the security threats discussed in the previous Chapter. In this Chapter we also
present recent fundamental bounds on the performance of any point-to-point QKD
protocol. We introduce TF-QKD by describing its first version and the improved
version that we investigate. We summarize the results of our investigation with
the support of plots simulating the protocol’s performance in realistic conditions.
Insight is provided on the theoretical results that enable a practical performance
assessment of TF-QKD. The last part of the Chapter is devoted to the discussion
of the CKA protocol inspired by the founding idea of TF-QKD.
• We start Chap. 7 by proving Bell’s theorem and introducing the concept of Bell
inequality. We show that quantum correlations can violate Bell inequalities and
clarify the relations between local, quantum, no-signaling and causal correlations.
We then elucidate the link between the violation of a Bell inequality and the
security of a device-independent (DI) QKD protocol. From there, we introduce the
archetypal DIQKD protocol based on the violation of the Clauser-Horne-ShimonyHolt inequality, and prove its security. We then present recent theoretical results
enabling similar security proofs for multipartite DI protocols. We conclude the
Chapter by presenting a multipartite Bell inequality specifically designed to be
employed in a DICKA protocol.
• Chapter 8 contains some concluding remarks and provides an outlook on future
research directions related to the topics addressed in the book.
References
1. Brassard, G. (2005). Brief history of quantum cryptography: A personal perspective. IEEE
Information Theory Workshop on Theory and Practice in Information-Theoretic Security, 19–
23.
2. Bennett, C. H., Brassard, G., Breidbart, S., & Wiesner, S. (1983). Quantum cryptography, or
unforgeable subway tokens. In Chaum, D., Rivest, R. L., & Sherman, A. T., (eds.) Advances
in Cryptology, pp. 267–275. Boston, MA: Springer US.
3. Wiesner, S. (1983). Conjugate coding. SIGACT News, 15(1), 78–88.
4. Bennett, C. H., & Brassard, G. (1984). Quantum cryptography: Public key distribution and
coin tossing. In Proceedings of IEEE International Conference on Computers, Systems and
Signal Processing, pp. 175 – 179.
5. Ekert, A. K. (1991). Quantum cryptography based on Bell’s theorem. Physical Review Letters,
67, 661–663.
6. Bruß, D. (1998). Optimal eavesdropping in quantum cryptography with six states. Physical
Review Letters, 81, 3018–3021.
1 Introduction
We then describe the functioning of a generic CKA protocol and prove its security.
Finally we describe the first experimental implementations of CKA protocols.
• In Chap. 5 we draw attention to the security threats posed by performing QKD with
imperfect quantum devices and discuss the solutions proposed so far. Specifically,
we present the decoy-state method to deal with sources emitting multiple photons.
We also introduce the concept of measurement-device-independent QKD, whose
security is independent of the trustworthiness of the measurement devices.
• The subject of Chap. 6 is the novel TF-QKD protocol, which applies the solutions
to the security threats discussed in the previous Chapter. In this Chapter we also
present recent fundamental bounds on the performance of any point-to-point QKD
protocol. We introduce TF-QKD by describing its first version and the improved
version that we investigate. We summarize the results of our investigation with
the support of plots simulating the protocol’s performance in realistic conditions.
Insight is provided on the theoretical results that enable a practical performance
assessment of TF-QKD. The last part of the Chapter is devoted to the discussion
of the CKA protocol inspired by the founding idea of TF-QKD.
• We start Chap. 7 by proving Bell’s theorem and introducing the concept of Bell
inequality. We show that quantum correlations can violate Bell inequalities and
clarify the relations between local, quantum, no-signaling and causal correlations.
We then elucidate the link between the violation of a Bell inequality and the
security of a device-independent (DI) QKD protocol. From there, we introduce the
archetypal DIQKD protocol based on the violation of the Clauser-Horne-ShimonyHolt inequality, and prove its security. We then present recent theoretical results
enabling similar security proofs for multipartite DI protocols. We conclude the
Chapter by presenting a multipartite Bell inequality specifically designed to be
employed in a DICKA protocol.
• Chapter 8 contains some concluding remarks and provides an outlook on future
research directions related to the topics addressed in the book.
References
1. Brassard, G. (2005). Brief history of quantum cryptography: A personal perspective. IEEE
Information Theory Workshop on Theory and Practice in Information-Theoretic Security, 19–
23.
2. Bennett, C. H., Brassard, G., Breidbart, S., & Wiesner, S. (1983). Quantum cryptography, or
unforgeable subway tokens. In Chaum, D., Rivest, R. L., & Sherman, A. T., (eds.) Advances
in Cryptology, pp. 267–275. Boston, MA: Springer US.
3. Wiesner, S. (1983). Conjugate coding. SIGACT News, 15(1), 78–88.
4. Bennett, C. H., & Brassard, G. (1984). Quantum cryptography: Public key distribution and
coin tossing. In Proceedings of IEEE International Conference on Computers, Systems and
Signal Processing, pp. 175 – 179.
5. Ekert, A. K. (1991). Quantum cryptography based on Bell’s theorem. Physical Review Letters,
67, 661–663.
6. Bruß, D. (1998). Optimal eavesdropping in quantum cryptography with six states. Physical
Review Letters, 81, 3018–3021.