193 research outputs found
A fundamental threat to quantum cryptography: gravitational attacks
An attack on the ``Bennett-Brassard 84''(BB84) quantum key-exchange protocol
in which Eve exploits the action of gravitation to infer information about the
quantum-mechanical state of the qubit exchanged between Alice and Bob, is
described. It is demonstrated that the known laws of physics do not allow to
describe the attack. Without making assumptions that are not based on broad
consensus, the laws of quantum gravity, unknown up to now, would be needed even
for an approximate treatment. Therefore, it is currently not possible to
predict with any confidence if information gained in this attack will allow to
break BB84. Contrary to previous belief, a proof of the perfect security of
BB84 cannot be based on the assumption that the known laws of physics are
strictly correct, yet.Comment: Eur. Phys. J. D (2006), in prin
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