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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]

The identity theft problem, an ever growing threat to safety and security in today's society, is very difficult to tackle using classical means, due to the fact that classical information can be easily read and copied. In this paper, we show that we can do more than it is possible classically through the use of specific tools and techniques from quantum information processing and quantum cryptography. Specifically, we devise a quantum security scheme that completely eliminates the problem of identity theft in sensor networks, although our scheme may be of interest in more general situations involving secrecy and authentication. The hypercomputational aspect of this result pertains to the unprecedented level of security achieved, a level that is beyond the reach of classical information processing. [ABSTRACT FROM AUTHOR]