Ottaviani, Carlo orcid.org/0000-0002-0032-3999 and Pirandola, Stefano orcid.org/0000-0001-6165-5615 (2016) General immunity and superadditivity of two-way Gaussian quantum cryptography. Scientific Reports. 22225. ISSN 2045-2322
Abstract
We consider two-way continuous-variable quantum key distribution, studying its security against general eavesdropping strategies. Assuming the asymptotic limit of many signals exchanged, we prove that two-way Gaussian protocols are immune to coherent attacks. More precisely we show the general superadditivity of the two-way security thresholds, which are proven to be higher than the corresponding one-way counterparts in all cases. We perform the security analysis first reducing the general eavesdropping to a two-mode coherent Gaussian attack, and then showing that the superadditivity is achieved by exploiting the random on/off switching of the two-way quantum communication. This allows the parties to choose the appropriate communication instances to prepare the key, accordingly to the tomography of the quantum channel. The random opening and closing of the circuit represents, in fact, an additional degree of freedom allowing the parties to convert, a posteriori, the two-mode correlations of the eavesdropping into noise. The eavesdropper is assumed to have no access to the on/off switching and, indeed, cannot adapt her attack. We explicitly prove that this mechanism enhances the security performance, no matter if the eavesdropper performs collective or coherent attacks.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This content is made available by the publisher under a Creative Commons Attribution Licence. This means that a user may copy, distribute and display the resource providing that they give credit. Users must adhere to the terms of the licence. |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Computer Science (York) |
Depositing User: | Pure (York) |
Date Deposited: | 07 Mar 2016 16:56 |
Last Modified: | 16 Dec 2024 00:06 |
Published Version: | https://doi.org/10.1038/srep22225 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1038/srep22225 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:96139 |