Security Assumptions in Dispersive-Optics QKD (2403.08992v1)
Abstract: Quantum key distribution (QKD) seeks to provide a method of generating cryptographically-secure keys between remote parties while guaranteeing unconditional security. Implementations of high-dimensional QKD using dispersive-optics (DO-QKD) have been proposed to allow for multiple secure bits to be transmitted per photon while remaining cost-effective and scalable using existing telecommunication technology [1]. In the recent literature, there have been a number of experimental realizations of DO-QKD systems [2-6], with security analysis based on the treatment in Ref. [1]. Here we demonstrate that in the case of finite dispersion, the model assumed for the eavesdropper's attack in Ref. [1] is non-optimal for the eavesdropper, which leads to a significant overestimation of the secure key rate between parties. We consider an alternative attack model that Alice and Bob find indistinguishable from the Ref. [1] model, as long as they are restricted to making the measurements typical in DO-QKD. We provide concrete examples where a significant gap exists between the Holevo information, and therefore the secret key rate, predicted by the two models. We further analyze the experiment in Ref. [2] as an example of a case where secure key is predicted according to the Ref. [1] model, but where in fact there is zero secure key rate when considering the full set of collective attacks that an eavesdropper may perform.
- C. H. Bennett and G. Brassard, Quantum cryptography: Public key distribution and coin tossing, Theoretical Computer Science 560, 7 (2014), theoretical Aspects of Quantum Cryptography – celebrating 30 years of BB84.
- A. K. Ekert, Quantum cryptography based on bell’s theorem, Phys. Rev. Lett. 67, 661 (1991).
- F. Grosshans and P. Grangier, Continuous variable quantum cryptography using coherent states, Phys. Rev. Lett. 88, 057902 (2002).
- N. J. Cerf, M. Lévy, and G. V. Assche, Quantum distribution of gaussian keys using squeezed states, Phys. Rev. A 63, 052311 (2001).
- L. Zhang, C. Silberhorn, and I. A. Walmsley, Secure quantum key distribution using continuous variables of single photons, Phys. Rev. Lett. 100, 110504 (2008).
- B. Qi, Single-photon continuous-variable quantum key distribution based on the energy-time uncertainty relation, Opt. Lett. 31, 2795 (2006).
- N. Fabre, A. Keller, and P. Milman, Time and frequency as quantum continuous variables, Phys. Rev. A 105, 052429 (2022).
- R. Garcia-Patron Sanchez, Quantum information with optical continuous variables: from Bell tests to key distribution, Ph.D. thesis, Université Libre de Bruxelles (2007).
- C. H. Bennett, G. Brassard, and N. D. Mermin, Quantum cryptography without bell’s theorem, Phys. Rev. Lett. 68, 557 (1992).
- W. H. Louisell, A. Yariv, and A. E. Siegman, Quantum fluctuations and noise in parametric processes. i., Phys. Rev. 124, 1646 (1961).
- D. C. Burnham and D. L. Weinberg, Observation of simultaneity in parametric production of optical photon pairs, Phys. Rev. Lett. 25, 84 (1970).
- V. C. Usenko and R. Filip, Trusted noise in continuous-variable quantum key distribution: A threat and a defense, Entropy 18, 10.3390/e18010020 (2016).
- M. M. Wolf, G. Giedke, and J. I. Cirac, Extremality of gaussian quantum states, Phys. Rev. Lett. 96, 080502 (2006).
- R. García-Patrón and N. J. Cerf, Unconditional optimality of gaussian attacks against continuous-variable quantum key distribution, Phys. Rev. Lett. 97, 190503 (2006).
- M. Navascués, F. Grosshans, and A. Acín, Optimality of gaussian attacks in continuous-variable quantum cryptography, Phys. Rev. Lett. 97, 190502 (2006).
- A. Leverrier and P. Grangier, Simple proof that gaussian attacks are optimal among collective attacks against continuous-variable quantum key distribution with a gaussian modulation, Phys. Rev. A 81, 062314 (2010).
- R. Renner and J. I. Cirac, de finetti representation theorem for infinite-dimensional quantum systems and applications to quantum cryptography, Phys. Rev. Lett. 102, 110504 (2009).
- S. Pirandola, S. L. Braunstein, and S. Lloyd, Characterization of collective gaussian attacks and security of coherent-state quantum cryptography, Phys. Rev. Lett. 101, 200504 (2008).
- R. Renner, N. Gisin, and B. Kraus, Information-theoretic security proof for quantum-key-distribution protocols, Phys. Rev. A 72, 012332 (2005).
- I. Devetak and A. Winter, Distillation of secret key and entanglement from quantum states, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 461, 207–235 (2005).
- N. J. Cerf and C. Adami, Accessible information in quantum measurement (1996), arXiv:quant-ph/9611032 [quant-ph] .
- I. Ali-Khan, C. J. Broadbent, and J. C. Howell, Large-alphabet quantum key distribution using energy-time entangled bipartite states, Phys. Rev. Lett. 98, 060503 (2007).
- J. D. Franson, Nonlocal cancellation of dispersion, Phys. Rev. A 45, 3126 (1992).
- I. Gel’fand and A. Yaglom, Calculation of the Amount of Information about a Random Function Contained in Another Such Function, American Mathematical Society translations (American Mathematical Society, 1959).
- C. Lee et al., High-dimensional quantum communication over deployed fiber, Ph.D. thesis, Massachusetts Institute of Technology (2018).