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Quantum bit commitment (QBC) is a quantum version of the classical bit commitment security primitive. As other quantum security primitives and protocols, QBC improves on cheating detection over its classical counterpart. The implementation of the QBC protocol below relies on the use of common quantum gates: the Hadamard gate used for orthonormal bases and the CNOT gate used to swap qubits. The protocol was run and tested on IBM quantum experience (IBM QX). IBM QX offers two different quantum environments: as a simulator and as a real quantum machine. In our implementation, honest and dishonest participants were considered. Results of both the simulation and the quantum execution were compared against the theoretical expectations. The IBM QX simulator gives results that match the theoretical model. The IBM QX real computer deviates from the expected behavior by a measurable amount. Using the standard deviation and the Hamming distance, the conclusion is that the quantum computer is usable as the difference to the simulator is within an acceptable margin of error. The QBC protocol of choice is fully secure against cheating by Bob. The only way Alice can cheat is using multi-dimensional entanglement. The cost for Alice to cheat is exponential in the number of qubits used, namely O (2 6 n + 3 k + 1) . [ABSTRACT FROM AUTHOR]

Byline: Marius Nagy, Selim G. Akl In this paper we show how the tree contraction method can be applied to compute the cardinality of the minimum vertex cover of a two-terminal series-parallel graph. We then construct a real-time paradigm for this problem and show that in the new computational environment, a parallel algorithm is superior to the best possible sequential algorithm, in terms of the accuracy of the solution computed. Specifically, there are cases in which the solution produced by a parallel algorithm that uses p processors is better than the output of any sequential algorithm for the same problem, by a factor superlinear in p.

Quantum bit commitment (QBC) is a fundamental cryptographic primitive that can be used as a building block for a whole set of applications like remote coin tossing, zero-knowledge proofs or secure two-party computation. Unconditionally secure QBC, that is a protocol which is both fully binding and fully concealing, is deemed impossible due to the use of entanglement by a dishonest participant [10, 14]. In this paper, we describe a protocol that implements QBC using quantum memories, meaning that a qubit can be stored for as long as needed. We prove that, in the absence of entanglement, our protocol exhibits both properties: it is both binding and concealing. Its security exploits the algebraic properties of an equivalence class with two types of operators: permutation and the Hadamard transform. The only theoretical attack that can be mounted concerns the binding property through the use of entanglement and the Schmidt decomposition. However, for all practical purposes, such an attack can be made arbitrarily difficult, by increasing the value of a security parameter, namely the number of qubits used in the protocol. [ABSTRACT FROM AUTHOR]

This paper explores parallels between concepts defined in cryptography and concepts of biology at different levels of organization. Cryptographic settings, including the presence of an eavesdropper are extensive in the realm of plants and animals. It also turns out that principles of information protection show strong similarities between the two disciplines: computer science and molecular biology. Biological information, as held by the DNA molecule, and digital information, as used in digital communication systems, are subject to analogous procedures of protection and repair when damaged. [ABSTRACT FROM AUTHOR]