Information Security and Cryptography Research Group

Small Accessible Quantum Information Does Not Imply Security

Robert Koenig, Renato Renner, Andor Bariska, and Ueli Maurer

Physical Review Letters, vol. 98, no. 140502, Apr 2007, Preliminary version available at

The security of quantum key distribution is typically defined in terms of the mutual information between the distributed key S and the outcome of an optimal measurement applied to the adversary's system. We show that even if this so-called accessible information is small, the key S might not be secure enough to be used in applications such as one-time pad encryption. This flaw is due to a locking property of the accessible information: one additional (physical) bit of information can increase the accessible information by more than one bit.

BibTeX Citation

    author       = {Robert Koenig and Renato Renner and Andor Bariska and Ueli Maurer},
    title        = {Small Accessible Quantum Information Does Not Imply Security},
    journal      = {Physical Review Letters},
    number       = {140502},
    volume       = {98},
    year         = {2007},
    month        = {4},
    note         = {Preliminary version available at},

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