3,336 research outputs found
An Experiment in Ping-Pong Protocol Verification by Nondeterministic Pushdown Automata
An experiment is described that confirms the security of a well-studied class
of cryptographic protocols (Dolev-Yao intruder model) can be verified by
two-way nondeterministic pushdown automata (2NPDA). A nondeterministic pushdown
program checks whether the intersection of a regular language (the protocol to
verify) and a given Dyck language containing all canceling words is empty. If
it is not, an intruder can reveal secret messages sent between trusted users.
The verification is guaranteed to terminate in cubic time at most on a
2NPDA-simulator. The interpretive approach used in this experiment simplifies
the verification, by separating the nondeterministic pushdown logic and program
control, and makes it more predictable. We describe the interpretive approach
and the known transformational solutions, and show they share interesting
features. Also noteworthy is how abstract results from automata theory can
solve practical problems by programming language means.Comment: In Proceedings MARS/VPT 2018, arXiv:1803.0866
A general scheme for information interception in the ping pong protocol
The existence of an undetectable eavesdropping of dense coded information has
been already demonstrated by Pavi\v{c}i\'c for the quantum direct communication
based on the ping-pong paradigm. However, a) the explicit scheme of the circuit
is only given and no design rules are provided, b) the existence of losses is
implicitly assumed, c) the attack has been formulated against qubit based
protocol only and it is not clear whether it can be adapted to higher
dimensional systems. These deficiencies are removed in the presented
contribution. A new generic eavesdropping scheme built on a firm theoretical
background is proposed. In contrast to the previous approach, it does not refer
to the properties of the vacuum state, so it is fully consistent with the
absence of losses assumption. Moreover, the scheme applies to the communication
paradigm based on signal particles of any dimensionality. It is also shown that
some well known attacks are special cases of the proposed scheme.Comment: 10 pages, 4 figure
Vulnerabilities in Quantum Key Distribution Protocols
Recently proposed quantum key distribution protocols are shown to be
vulnerable to a classic man-in-the-middle attack using entangled pairs created
by Eve. It appears that the attack could be applied to any protocol that relies
on manipulation and return of entangled qubits to create a shared key. The
protocols that are cryptanalyzed in this paper were proven secure with respect
to some eavesdropping approaches, and results reported here do not invalidate
these proofs. Rather, they suggest that quantum cryptographic protocols, like
conventional protocols, may be vulnerable to methods of attack that were not
envisaged by their designers.Comment: 6 pages, 1 figur
- …