1,046 research outputs found
Dense-Coding Attack on Three-Party Quantum Key Distribution Protocols
Cryptanalysis is an important branch in the study of cryptography, including
both the classical cryptography and the quantum one. In this paper we analyze
the security of two three-party quantum key distribution protocols (QKDPs)
proposed recently, and point out that they are susceptible to a simple and
effective attack, i.e. the dense-coding attack. It is shown that the
eavesdropper Eve can totally obtain the session key by sending entangled qubits
as the fake signal to Alice and performing collective measurements after
Alice's encoding. The attack process is just like a dense-coding communication
between Eve and Alice, where a special measurement basis is employed.
Furthermore, this attack does not introduce any errors to the transmitted
information and consequently will not be discovered by Alice and Bob. The
attack strategy is described in detail and a proof for its correctness is
given. At last, the root of this insecurity and a possible way to improve these
protocols are discussed.Comment: 6 pages, 3 figure
Cryptanalysis of the Hillery-Buzek-Berthiaume quantum secret-sharing protocol
The participant attack is the most serious threat for quantum secret-sharing
protocols. We present a method to analyze the security of quantum
secret-sharing protocols against this kind of attack taking the scheme of
Hillery, Buzek, and Berthiaume (HBB) [Phys. Rev. A 59 1829 (1999)] as an
example. By distinguishing between two mixed states, we derive the necessary
and sufficient conditions under which a dishonest participant can attain all
the information without introducing any error, which shows that the HBB
protocol is insecure against dishonest participants. It is easy to verify that
the attack scheme of Karlsson, Koashi, and Imoto [Phys. Rev. A 59, 162 (1999)]
is a special example of our results. To demonstrate our results further, we
construct an explicit attack scheme according to the necessary and sufficient
conditions. Our work completes the security analysis of the HBB protocol, and
the method presented may be useful for the analysis of other similar protocols.Comment: Revtex, 7 pages, 3 figures; Introduction modifie
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