Quantum-key-distribution protocols without sifting that are resistant to photon-number-splitting attacks

Abstract

We show that replacing the usual sifting step of the standard quantum-key-distribution protocol BB84 [1] by a one-way reverse reconciliation procedure increases its robustness against photonnumber-splitting (pns) attacks to the level of the SARG04 protocol [2,3] while keeping the raw key-rate of BB84. This protocol, which uses the same state and detection than BB84, is the m = 4 member of a protocol-family using m polarization states which we introduce here. We show that the robustness of these protocols against pns attacks increases exponentially with m, and that the effective keyrate of optimized weak coherent pulses decreases with the transmission T like T 1+ 1 m−2 .PACS numbers: 03.67. Ac, 03.67.Dd, 03.67.Hk Over the last 25 years, quantum key distribution (QKD) has emerged as the main application of quantum information. In most experimental realizations [4], the legitimate partners -traditionally named Alice and Bob -use the BB84 protocol [1] with weak-coherentpulses (wcp), i.e. Alice sends polarized coherent states to Bob, and Bob measures their polarization to obtain the raw-key. Alice and Bob then post-select a subset of the measurement to obtain the sifted-key from which the cryptographic key is extracted. If Alice sends perfect single-photons, there is no way for an eavesdroppertraditionally named Eve -to learn anything about the sifted key without introducing errors. But, with wcps, Alice only approximates single-photon, and she sometimes sends multiphoton pulses, on which Eve can get all the information through photon-number-splitting (pns) attack [5]. SARG04 [2,3] showed that, with the same modulation and detection than BB84, one can construct a protocol more robust against pns, since Eve only gains partial information from 2 photons pulse and needs to wait for the rarer 3 photons pulses to gain the full information. However, for the same pulse intensity, SARG04's rate is the half of BB84 at low losses, because of the lower rate of it sifting. As shown in [3] SARG04's robustness can be increased by using m polarizations instead of 4, at the price of a lower sifting rate ∝ m −3 . This article shows that this price is not necessary, and that it is possible to have the best of both protocols, i.e. BB84's rate and SARG04's robustness against photon numbersplitting attacks.BB84 and SARG04 are sifting based protocols i.e. protocols where a part of the data is "sifted away" because Alice's state and Bob's measurement are not in the "same basis". We will look here at sifting-less protocols, i.e. protocols where this discussion is absent, and therefore, where the "wrong-basis" data are kept in the raw-key.Protocol description. Alice randomly choses one linear polarization and sends the corresponding phaserandomized weak coherent pulse (wcp). Let m ≥ 3 the total number of possible polarizations. To simplify the analysis, we will suppose that the polarizations are uniformly distributed along a great circle of Poincaré's sphere. Let |0 and |1 be the state of two orthogonally polarized single photons. If the ...

Security Analysis of the Multi-Photon Three-Stage Quantum Key Distribution

“…It is remarked that the use of many polarization angles to increase the robustness of QKD protocols has also been explored in [17,18]. In addition, the scheme described here can in principle be applied to other degrees of freedom of the photons just like the Y00 protocol [19,20] and the state X can be extended to multi-alphabet qudit systems.…”

Introduction to quantum information theory and outline of two applications to physics: the black hole information paradox and the renormalization group information flow

“…This means in other terms that the Bob can not access the information of Alice. This situation expresses the concept of quantum complementarity, and based on this concept Charles Bennett and Gilles Brassard in 1984 devised the idea of quantum cryptography [19], which over the years has become one of the most developed applications of QIT [20,21,22,23,24]. (30).…”

Photon-number Splitting Attack on SARG04 Protocol

“…is analyzed by guaranteed the line length up to which a secret key distribution to determine both the protocol itself and the efficiency of error correction in raw keys (Sinil'shchikov and Molotkov, 2019). Proposed a family of sifting-less quantum-key-distribution protocols which use reverse reconciliation, and are based on weak coherent pulses (WCPs) polarized along different directions and also the physical part of the protocol is identical to most experimental implementations of BB84 and SARG04 protocols and they differ only in classical communications and data processing (Grazioso and Grosshans, 2013). The performance analysis of SARG04 and KMB09 protocols was presented with respect to protocol efficiency, Quantum Bit Error Rate (QBER), and robustness against eavesdropping (Lopes and Sarwade, 2015).…”