9 research outputs found
Cryptanalysis of a multi-party quantum key agreement protocol with single particles
Recently, Sun et al. [Quant Inf Proc DOI: 10.1007/s11128-013-0569-x]
presented an efficient multi-party quantum key agreement (QKA) protocol by
employing single particles and unitary operations. The aim of this protocol is
to fairly and securely negotiate a secret session key among parties with a
high qubit efficiency. In addition, the authors claimed that no participant can
learn anything more than his/her prescribed output in this protocol, i.e., the
sub-secret keys of the participants can be kept secret during the protocol.
However, here we points out that the sub-secret of a participant in Sun et
al.'s protocol can be eavesdropped by the two participants next to him/her. In
addition, a certain number of dishonest participants can fully determine the
final shared key in this protocol. Finally, we discuss the factors that should
be considered when designing a really fair and secure QKA protocol.Comment: 7 page
Orthogonal-state-based protocols of quantum key agreement
Two orthogonal-state-based protocols of quantum key agreement (QKA) are
proposed. The first protocol of QKA proposed here is designed for two-party
QKA, whereas the second protocol is designed for multi-party QKA. Security of
these orthogonal-state-based protocols arise from monogamy of entanglement.
This is in contrast to the existing protocols of QKA where security arises from
the use of non-orthogonal state (non-commutativity principle). Further, it is
shown that all the quantum systems that are useful for implementation of
quantum dialogue and most of the protocols of secure direct quantum
communication can be modified to implement protocols of QKA.Comment: 9 pages, no figur
Quantum sealed-bid auction using a modified scheme for multiparty circular quantum key agreement
A feasible, secure and collusion-attack-free quantum sealed-bid auction
protocol is proposed using a modified scheme for multi-party circular quantum
key agreement. In the proposed protocol, the set of all () bidders is
grouped in to subsets (sub-circles) in such a way that only the initiator
(who prepares the quantum state to be distributed for a particular round of
communication and acts as the receiver in that round) is a member of all the
subsets (sub-circles) prepared for a particular round, while any other bidder
is part of only a single subset. All bidders and auctioneer initiate one
round of communication, and each of them prepares copies of a
-partite entangled state (one for each sub-circle), where
. The efficiency and security\textcolor{blue}{{} }of the
proposed protocol are critically analyzed. It is shown that the proposed
protocol is free from the collusion attacks that are possible on the existing
schemes of quantum sealed-bid auction. Further, it is observed that the
security against collusion attack increases with the increase in , but that
reduces the complexity (number of entangled qubits in each entangled state) of
the entangled states to be used and that makes the scheme scalable and
implementable with the available technologies. The additional security and
scalability is shown to arise due to the use of a circular structure in place
of a complete-graph or tree-type structure used earlier.Comment: 10 pages, 2 figure
Semi-quantum communication: Protocols for key agreement, controlled secure direct communication and dialogue
Semi-quantum protocols that allow some of the users to remain classical are
proposed for a large class of problems associated with secure communication and
secure multiparty computation. Specifically, first time semi-quantum protocols
are proposed for key agreement, controlled deterministic secure communication
and dialogue, and it is shown that the semi-quantum protocols for controlled
deterministic secure communication and dialogue can be reduced to semi-quantum
protocols for e-commerce and private comparison (socialist millionaire
problem), respectively. Complementing with the earlier proposed semi-quantum
schemes for key distribution, secret sharing and deterministic secure
communication, set of schemes proposed here and subsequent discussions have
established that almost every secure communication and computation tasks that
can be performed using fully quantum protocols can also be performed in
semi-quantum manner. Further, it addresses a fundamental question in context of
a large number problems- how much quantumness is (how many quantum parties are)
required to perform a specific secure communication task? Some of the proposed
schemes are completely orthogonal-state-based, and thus, fundamentally
different from the existing semi-quantum schemes that are
conjugate-coding-based. Security, efficiency and applicability of the proposed
schemes have been discussed with appropriate importance.Comment: 19 pages 1 figur