dorsal/arxiv
View SchemaSecurity of quantum key distribution using weak coherent states with nonrandom phases
| Authors | Hoi-Kwong Lo, John Preskill |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0610203 |
| URL | https://arxiv.org/abs/quant-ph/0610203 |
| Journal | Quant. Inf. Comput. 8 (2007) 431-458 |
Abstract
We prove the security of the Bennett-Brassard (BB84) quantum key distribution protocol in the case where the key information is encoded in the relative phase of a coherent-state reference pulse and a weak coherent-state signal pulse, as in some practical implementations of the protocol. In contrast to previous work, our proof applies even if the eavesdropper knows the phase of the reference pulse, provided that this phase is not modulated by the source, and even if the reference pulse is bright. The proof also applies to the case where the key is encoded in the photon polarization of a weak coherent-state pulse with a known phase, but only if the phases of the four BB84 signal states are judiciously chosen. The achievable key generation rate scales quadratically with the transmission in the channel, just as for BB84 with phase-randomized weak coherent-state signals (when decoy states are not used). For the case where the phase of the reference pulse is strongly modulated by the source, we exhibit an explicit attack that allows the eavesdropper to learn every key bit in a parameter regime where a protocol using phase-randomized signals is provably secure.
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"abstract": "We prove the security of the Bennett-Brassard (BB84) quantum key distribution\nprotocol in the case where the key information is encoded in the relative phase\nof a coherent-state reference pulse and a weak coherent-state signal pulse, as\nin some practical implementations of the protocol. In contrast to previous\nwork, our proof applies even if the eavesdropper knows the phase of the\nreference pulse, provided that this phase is not modulated by the source, and\neven if the reference pulse is bright. The proof also applies to the case where\nthe key is encoded in the photon polarization of a weak coherent-state pulse\nwith a known phase, but only if the phases of the four BB84 signal states are\njudiciously chosen. The achievable key generation rate scales quadratically\nwith the transmission in the channel, just as for BB84 with phase-randomized\nweak coherent-state signals (when decoy states are not used). For the case\nwhere the phase of the reference pulse is strongly modulated by the source, we\nexhibit an explicit attack that allows the eavesdropper to learn every key bit\nin a parameter regime where a protocol using phase-randomized signals is\nprovably secure.",
"arxiv_id": "quant-ph/0610203",
"authors": [
"Hoi-Kwong Lo",
"John Preskill"
],
"categories": [
"quant-ph"
],
"journal_ref": "Quant. Inf. Comput. 8 (2007) 431-458",
"title": "Security of quantum key distribution using weak coherent states with nonrandom phases",
"url": "https://arxiv.org/abs/quant-ph/0610203"
},
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