24,314 research outputs found
Towards Communication-Efficient Quantum Oblivious Key Distribution
Oblivious Transfer, a fundamental problem in the field of secure multi-party
computation is defined as follows: A database DB of N bits held by Bob is
queried by a user Alice who is interested in the bit DB_b in such a way that
(1) Alice learns DB_b and only DB_b and (2) Bob does not learn anything about
Alice's choice b. While solutions to this problem in the classical domain rely
largely on unproven computational complexity theoretic assumptions, it is also
known that perfect solutions that guarantee both database and user privacy are
impossible in the quantum domain. Jakobi et al. [Phys. Rev. A, 83(2), 022301,
Feb 2011] proposed a protocol for Oblivious Transfer using well known QKD
techniques to establish an Oblivious Key to solve this problem. Their solution
provided a good degree of database and user privacy (using physical principles
like impossibility of perfectly distinguishing non-orthogonal quantum states
and the impossibility of superluminal communication) while being loss-resistant
and implementable with commercial QKD devices (due to the use of SARG04).
However, their Quantum Oblivious Key Distribution (QOKD) protocol requires a
communication complexity of O(N log N). Since modern databases can be extremely
large, it is important to reduce this communication as much as possible. In
this paper, we first suggest a modification of their protocol wherein the
number of qubits that need to be exchanged is reduced to O(N). A subsequent
generalization reduces the quantum communication complexity even further in
such a way that only a few hundred qubits are needed to be transferred even for
very large databases.Comment: 7 page
Quantum private queries
We propose a cheat sensitive quantum protocol to perform a private search on
a classical database which is efficient in terms of communication complexity.
It allows a user to retrieve an item from the server in possession of the
database without revealing which item she retrieved: if the server tries to
obtain information on the query, the person querying the database can find it
out. Furthermore our protocol ensures perfect data privacy of the database,
i.e. the information that the user can retrieve in a single queries is bounded
and does not depend on the size of the database. With respect to the known
(quantum and classical) strategies for private information retrieval, our
protocol displays an exponential reduction both in communication complexity and
in running-time computational complexity.Comment: 4 pages, 1 figur
Blind quantum machine learning with quantum bipartite correlator
Distributed quantum computing is a promising computational paradigm for
performing computations that are beyond the reach of individual quantum
devices. Privacy in distributed quantum computing is critical for maintaining
confidentiality and protecting the data in the presence of untrusted computing
nodes. In this work, we introduce novel blind quantum machine learning
protocols based on the quantum bipartite correlator algorithm. Our protocols
have reduced communication overhead while preserving the privacy of data from
untrusted parties. We introduce robust algorithm-specific privacy-preserving
mechanisms with low computational overhead that do not require complex
cryptographic techniques. We then validate the effectiveness of the proposed
protocols through complexity and privacy analysis. Our findings pave the way
for advancements in distributed quantum computing, opening up new possibilities
for privacy-aware machine learning applications in the era of quantum
technologies.Comment: 11 pages, 3 figure
The impossibility of non-signaling privacy amplification
Barrett, Hardy, and Kent have shown in 2005 that protocols for quantum key
agreement exist the security of which can be proven under the assumption that
quantum or relativity theory is correct. More precisely, this is based on the
non-local behavior of certain quantum systems, combined with the non-signaling
postulate from relativity. An advantage is that the resulting security is
independent of what (quantum) systems the legitimate parties' devices operate
on: they do not have to be trusted. Unfortunately, the protocol proposed by
Barrett et al. cannot tolerate any errors caused by noise in the quantum
channel. Furthermore, even in the error-free case it is inefficient: its
communication complexity is Theta(1/epsilon) when forcing the attacker's
information below epsilon, even if only a single key bit is generated.
Potentially, the problem can be solved by privacy amplification of relativistic
- or non-signaling - secrecy. We show, however, that such privacy amplification
is impossible with respect to the most important form of non-local behavior,
and application of arbitrary hash functions.Comment: 24 pages, 2 figure
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