Practical challenges in quantum key distribution

Abstract

Quantum key distribution (QKD) promises unconditional security in data communication and is currently being deployed in commercial applications. Nonetheless, before QKD can be widely adopted, it faces a number of important challenges such as secret key rate, distance, size, cost and practical security. Here, we survey those key challenges and the approaches that are currently being taken to address them. For thousands of years, human beings have been using codes to keep secrets. With the rise of the Internet and recent trends to the Internet of Things, our sensitive personal financial and health data as well as commercial and national secrets are routinely being transmitted through the Internet. In this context, communication security is of utmost importance. In conventional symmetric cryptographic algorithms, communication security relies solely on the secrecy of an encryption key. If two users, Alice and Bob, share a long random string of secret bits-the key-then they can achieve unconditional security by encrypting their message using the standard one-time-pad encryption scheme. The central question then is: how do Alice and Bob share a secure key in the first place? This is called the key distribution problem. Unfortunately, all classical methods to distribute a secure key are fundamentally insecure because in classical physics there is nothing preventing an eavesdropper, Eve, from copying the key during its transit from Alice to Bob. On the other hand, standard asymmetric or public-key cryptography solves the key distribution problem by relying on computational assumptions such as the hardness of factoring. Therefore, such schemes do not provide information-theoretic security because they are vulnerable to future advances in hardware and algorithms, including the construction of a large-scale quantum computer.

Progrés et défis pour la cryptographie quantique

“…Le but ultime est de fournir un niveau maximal, correspondant à la sécurité contre les attaques les plus générales, avec un débit et une distance de communication qui sont compatibles avec des applications pratiques. Quelques expériences ré-centes ont fourni des bonnes performances et définissent l'état de l'art dans le domaine pour les liaisons fibrées [4] (figure 2).…”

Quantum secure communication models comparison

“…For the quantum particles used in the quantum communications are photons, the quantum primitives can be deployed into the already installed telecommunication optical resource, but with one exception: in some cases, the terminal devices that are to be used for implementing quantum communications have to be of one-photon type (Bebrov, 2017), (Diamanti, 2016). Establishing a quantum channel means sharing quantum particles between two or more parties.…”

“…Based on the above-stated points, the most common and prominent quantum primitives existing to date have been developed: the quantum key distribution (Bebrov, 2017;Diamanti, 2016) and quantum secure communication (Long, 2007). The QKD is the process of securely sharing a key between parties in a quantum way, i.e., transferring the key information particle by particle, as shown in Fig.1a.…”

Squeezing-enhanced phase-shift-keyed binary communication in noisy channels

“…As such, it has attracted attention from a fundamental point of view [1][2][3][4][5][6][7][8][9], and represents a central tool for the design and development of quantum communication channels. In particular, much attention has been payed to quantum binary discrimination, which already shows a rich quantum phenomenology amenable to analytic investigations and fosters promising perspectives in a number of challenging applications, such as quantum communication [10,11] and quantum cryptography [12]. In particular, quantum-optical implementations of state discrimination have been investigated [13][14][15], with the focus on information carried by coherent states [16,17], although also the use of squeezing has been explored to some extent [18,19].…”