325 research outputs found
Quantum Private Information Retrieval from Coded Storage Systems
In the era of extensive data growth, robust and efficient mechanisms are
needed to store and manage vast amounts of digital information, such as Data
Storage Systems (DSSs). Concurrently, privacy concerns have arisen, leading to
the development of techniques like Private Information Retrieval (PIR) to
enable data access while preserving privacy. A PIR protocol allows users to
retrieve information from a database without revealing the specifics of their
query or the data they are accessing.
With the advent of quantum computing, researchers have explored the potential
of using quantum systems to enhance privacy in information retrieval. In a
Quantum Private Information Retrieval (QPIR) protocol, a user can retrieve
information from a database by downloading quantum systems from multiple
servers, while ensuring that the servers remain oblivious to the specific
information being accessed. This scenario offers a unique advantage by
leveraging the inherent properties of quantum systems to provide enhanced
privacy guarantees and improved communication rates compared to classical PIR
protocols.
In this thesis we consider the QPIR setting where the queries and the coded
storage systems are classical, while the responses from the servers are
quantum. This problem was treated by Song et al. for replicated storage and
different collusion patterns. This thesis aims to develop QPIR protocols for
coded storage by combining known classical PIR protocols with quantum
communication algorithms, achieving enhanced privacy and communication costs.
We consider different storage codes and robustness assumptions, and we prove
that the achieved communication cost is always lower than the classical
counterparts.Comment: This is the summary part of an article collection-based PhD thesi
Quantum Symmetric Private Information Retrieval with Secure Storage and Eavesdroppers
We consider both the classical and quantum variations of -secure,
-eavesdropped and -colluding symmetric private information retrieval
(SPIR). This is the first work to study SPIR with -security in classical or
quantum variations. We first develop a scheme for classical -secure,
-eavesdropped and -colluding SPIR (XSETSPIR) based on a modified version
of cross subspace alignment (CSA), which achieves a rate of . The modified scheme achieves the same rate as the
scheme used for -secure PIR with the extra benefit of symmetric privacy.
Next, we extend this scheme to its quantum counterpart based on the -sum box
abstraction. This is the first work to consider the presence of eavesdroppers
in quantum private information retrieval (QPIR). In the quantum variation, the
eavesdroppers have better access to information over the quantum channel
compared to the classical channel due to the over-the-air decodability. To that
end, we develop another scheme specialized to combat eavesdroppers over quantum
channels. The scheme proposed for -secure, -eavesdropped and
-colluding quantum SPIR (XSETQSPIR) in this work maintains the super-dense
coding gain from the shared entanglement between the databases, i.e., achieves
a rate of
Code-Based Single-Server Private Information Retrieval: Circumventing the Sub-Query Attack
Private information retrieval from a single server is considered, utilizing
random linear codes. Presented is a modified version of the first code-based
single-server computational PIR scheme proposed by Holzbaur, Hollanti, and
Wachter-Zeh in [Holzbaur et al., "Computational Code-Based Single-Server
Private Information Retrieval", 2020 IEEE ISIT]. The original scheme was broken
in [Bordage et al., "On the privacy of a code-based single-server computational
PIR scheme", Cryptogr. Comm., 2021] by an attack arising from highly probable
rank differences in sub-matrices of the user's query. Here, this attack is now
circumvented by ensuring that the sub-matrices have negligible rank difference.
Furthermore, the rank difference cannot be attributed to the desired file
index, thereby ensuring the privacy of the scheme. In the case of retrieving
multiple files, the rate of the modified scheme is largely unaffected and at
par with the original scheme.Comment: The scheme proposed in this work is a modified version of the scheme
in arXiv:2001.07049 (IEEE ISIT 2020) and provides a mend against the attack
discovered in arXiv:2004.00509 (Cryptography and Communications, 2021
Two-Server Oblivious Transfer for Quantum Messages
Oblivious transfer is considered as a cryptographic primitive task for
quantum information processing over quantum network. Although it is possible
with two servers, any existing protocol works only with classical messages. We
propose two-server oblivious transfer protocols for quantum messages
Prior Entanglement Exponentially Improves One-Server Quantum Private Information Retrieval for Quantum Messages
Quantum private information retrieval (QPIR) for quantum messages is a
quantum communication task, in which a user retrieves one of the multiple
quantum states from the server without revealing which state is retrieved. In
the one-server setting, we find an exponential gap in the communication
complexities between the presence and absence of prior entanglement in this
problem with the one-server setting. To achieve this aim, as the first step, we
prove that the trivial solution of downloading all messages is optimal under
QPIR for quantum messages, which is a similar result to that of classical PIR
but different from QPIR for classical messages. As the second step, we propose
an efficient one-server one-round QPIR protocol with prior entanglement by
constructing a reduction from a QPIR protocol for classical messages to a QPIR
protocol for quantum messages in the presence of prior entanglement
On the Capacity of Secure -user Product Computation over a Quantum MAC
Inspired by a recent study by Christensen and Popovski on secure -user
product computation for finite-fields of prime-order over a quantum multiple
access channel (QMAC), the generalization to users and arbitrary finite
fields is explored. Combining ideas of batch-processing, quantum -sum
protocol, a secure computation scheme of Feige, Killian and Naor (FKN), a
field-group isomorphism and additive secret sharing, asymptotically optimal
(capacity-achieving for large alphabet) schemes are proposed for secure
-user (any ) product computation over any finite field. The capacity of
modulo- () secure -sum computation over the QMAC is found to be
computations/qudit as a byproduct of the analysis
A new hardware-assisted PIR with O(n) shuffle cost
Ministry of Education, Singapore under its Academic Research Funding Tier
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