36 research outputs found
Flexible quantum private queries based on quantum key distribution
We present a flexible quantum-key-distribution-based protocol for quantum
private queries. Similar to M. Jakobi et al's protocol [Phys. Rev. A 83, 022301
(2011)], it is loss tolerant, practical and robust against quantum memory
attack. Furthermore, our protocol is more flexible and controllable. We show
that, by adjusting the value of , the average number of the key bits
Alice obtains can be located on any fixed value the users wanted for any
database size. And the parameter is generally smaller (even can be
achieved) when , which implies lower complexity of both quantum
and classical communications. Furthermore, the users can choose a smaller
to get better database security, or a larger to obtain a
lower probability with which Bob can correctly guess the address of Alice's
query.Comment: 6 pages, 5 figure
Improved and Formal Proposal for Device Independent Quantum Private Query
In this paper, we propose a novel Quantum Private Query (QPQ) scheme with
full Device-Independent certification. To the best of our knowledge, this is
the first time we provide such a full DI-QPQ scheme using EPR-pairs. Our
proposed scheme exploits self-testing of shared EPR-pairs along with the
self-testing of projective measurement operators in a setting where the client
and the server do not trust each other. To certify full device independence, we
exploit a strategy to self-test a particular class of POVM elements that are
used in the protocol. Further, we provide formal security analysis and obtain
an upper bound on the maximum cheating probabilities for both the dishonest
client as well as the dishonest server.Comment: 33 pages, 2 figure
Quantum cryptography: key distribution and beyond
Uniquely among the sciences, quantum cryptography has driven both
foundational research as well as practical real-life applications. We review
the progress of quantum cryptography in the last decade, covering quantum key
distribution and other applications.Comment: It's a review on quantum cryptography and it is not restricted to QK
Quantum Cryptography: Key Distribution and Beyond
Uniquely among the sciences, quantum cryptography has driven both foundational research as well as practical real-life applications. We review the progress of quantum cryptography in the last decade, covering quantum key distribution and other applications.Quanta 2017; 6: 1–47
Semi-Quantum Conference Key Agreement (SQCKA)
A need in the development of secure quantum communications is the scalable extension
of key distribution protocols. The greatest advantage of these protocols is the fact that its
security does not rely on mathematical assumptions and can achieve perfect secrecy. In
order to make these protocols scalable, has been developed the concept of Conference
Key Agreements, among multiple users.
In this thesis we propose a key distribution protocol among several users using a
semi-quantum approach. We assume that only one of the users is equipped with quantum
devices and generates quantum states, while the other users are classical, i.e., they are only
equipped with a device capable of measuring or reflecting the information. This approach has
the advantage of simplicity and reduced costs.
We prove our proposal is secure and we present some numerical results on the lower
bounds for the key rate. The security proof applies new techniques derived from some
already well established work.
From the practical point of view, we developed a toolkit called Qis|krypt⟩ that is able to
simulate not only our protocol but also some well-known quantum key distribution protocols.
The source-code is available on the following link:
- https://github.com/qiskrypt/qiskrypt/.Uma das necessidades no desenvolvimento de comunicações quânticas seguras é a extensão
escalável de protocolos de distribuição de chaves. A grande vantagem destes protocolos é o
facto da sua segurança não depender de suposições matemáticas e poder atingir segurança
perfeita. Para tornar estes protocolos escaláveis, desenvolveu-se o conceito de Acordo
de Chaves de Conferência, entre múltiplos utilizadores.
Nesta tese propomos um protocolo para distribuição de chaves entre vários utilizadores
usando uma abordagem semi-quântica. Assumimos que apenas um dos utilizadores está
equipado com dispositivos quânticos e é capaz de gerar estados quânticos, enquanto que
os outros utilizadores são clássicos, isto é, estão apenas equipados com dispositivos capazes
de efectuar uma medição ou refletir a informação. Esta abordagem tem a vantagem de ser
mais simples e de reduzir custos.
Provamos que a nossa proposta é segura e apresentamos alguns resultados numéricos
sobre limites inferiores para o rácio de geração de chaves. A prova de segurança aplica novas
técnicas derivadas de alguns resultados já bem estabelecidos.
Do ponto de vista prático, desenvolvemos uma ferramenta chamada Qis|krypt⟩ que é capaz
de simular não só o nosso protocolo como também outros protocolos distribuição de chaves
bem conhecidos. O código fonte encontra-se disponÃvel no seguinte link:
- https://github.com/qiskrypt/qiskrypt/