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[转载]Backdoors in Practical QKD

[转载]Backdoors in Practical QKD

原始出处:http://qoptics.quantumlah.org/la ... o/hacking/hack.html

Since it was originally proposed in 1984, a lot of effort has gone into proving the security of quantum key distribution. These theoretical proofs have evolved from highly idealized scenarios to incorporating some imperfections, but ultimately are based on a set of assumptions.

We explore deviations from these assumptions which lead to the cryptographic systems becoming insecure. In particular, we look at timing information that is publicly exchanged by the communicating parties. All single photon implementations of QKD identify a photon from backgroun by measurement of the arrival time at detectors. In principle, there should be no correlations between this arrival time and the result of the measurement.

Measurement setup

Figure 1. Configuration of photocounting detector and polarization analysis for QKD with a passive basis choice.


Figure 2. Experimental setup to characterize the timing jitter of a single photodetector. A train of ultrashort light pulses from a mode-locked Ti:Sa laser are sent into the 4 detector module and the response time of the detectors is characterized.


Detector response and information leakage
The detector response is non-identical for the different APDs representing different measurement outcomes. Since this information is discussed publicly, we must quantify how much information about the key is in principle leaking out to an eavesdropper.


Figure 3. Photoevent timing histograms for the four detectors in a QKD receiver. The overall shape is similar but the position of the centroid of the distributions can be significantly different.


Figure 4. Eve's information as a function of the delay between detector timing distributions with identical shapes.


Figure 4 shows how relatively small differences in detector response lead to large portions of the key becoming insecure. For example, if the detector response time is equalized only up to half a nanosecond, which is about the intrisic jitter, then Eve could have access to more than 25% of the "secret key".

Research Articles
Breaking a quantum key distribution system through a timing side channel. Antia Lamas-Linares and Christian Kurtsiefer, arxiv:quant-ph/0704.3297, Opt. Express 15, 9388 (2007).
Experimental demonstration of four-party quantum secret sharing. Sasha Gaertner, Christian Kurtsiefer, Mohammed Bourennane, Harald Weinfurter, Phys. Rev. Lett 98, 020503 (2007).
Joint Spectrum Mapping of Polarization Entanglement in Spontaneous Parametric Down-conversion. Hou Shun Poh, Chune Yang Lum, Ivan Marcikic, Antia Lamas-Linares, Christian Kurtsiefer, Phys. Rev. A 75, 043816 (2007).
2006
Free-space quantum key distribution with entangled photons. Ivan Marcikic, Antia Lamas-Linares, Christian Kurtsiefer. Applied Physics Letters 89, 101122 (2006).
Experimental quantum secret sharing. Christian Schmid, Pavel Trojek, Sascha Gaertner, Mohamed Bourennane, Christian Kurtsiefer, Marek Zukowski, and Harald Weinfurter, Fortschr. Phys. 54, 831-839 (2006).
Experimental Polarization State Tomography using Optimal Polarimeters. Alex Ling, Soh Kee Pang, Antia Lamas-Linares, Christian Kurtsiefer. Phys. Rev. A 74, 022309 (2006).
Preparation of Bell States with Controlled White Noise. Alex Ling, Peng Yuan Han, Antia Lamas-Linares, Christian Kurtsiefer. Laser Physics 16, 1140 (2006).
Observation of Entanglement of a Single Photon with a Trapped Atom. Volz, M. Weber, D. Schlenk, W. Rosenfeld, J. Vrana, K. Saucke, C. Kurtsiefer, and H. Weinfurter, Phys. Rev. Lett. 96, 030404 (2006).
An Optimal Photon Counting Polarimeter. Alex Ling, Soh Kee Pang, Antia Lamas-Linares, Christian Kurtsiefer, Journal of Modern Optics 53, 1523 (2006).
Complete Deterministic Linear Optics Bell State Analysis. Carsten Schuck, Gerhard Huber, Christian Kurtsiefer, and Harald Weinfurter, Phys. Rev. Lett. 96, 190501 (2006).
Entanglement Persistency of Multiphoton Entangled States. M. Bourennane, M. Eibl, S. Gaertner, N. Kiesel, Ch. Kurtsiefer, and H. Weinfurter:, Phys. Rev. Lett. 96, 100502 (2006).
Experimental noise resistant Bell inequality violations for polarization-entangled photons. Fabio A. Bovino, Giuseppe Castagnoli, Adan Cabello, Antia Lamas-Linares. Phys. Rev. A 73, 062110 (2006).
Analysis of a single-atom dipole trap. Markus Weber, Juergen Volz, Karen Saucke, Christian Kurtsiefer, and Harald Weinfurter, Phys. Rev. A 73, 043406 (2006).
Single photon emission from SiV centres in diamond produced by ion implantation. C. Wang, Ch. Kurtsiefer, H. Weinfurter and B. Burchard, J. Phys. B 39, 37-41 (2006).
2005
Fast and compact multichannel photon coincidence unit for quantum information processing. S. Gaertner, H. Weinfurter, and Ch. Kurtsiefer: Rev. Sci. Instrum. 76, 123108 (2005).
Bell's inequalities with realistic noise for polarization-entangled photons. Adan Cabello, Alvaro Feito, Antia Lamas-Linares, Phys. Rev. A 72, 052112 (2005).
Experimental Single Qubit Quantum Secret Sharing. C. Schmid, P. Trojek, M. Bourennane, Ch. Kurtsiefer, M. Zukowski, and H. Weinfurter, Phys. Rev. Lett. 95, 230505 (2005).

More articles
For a complete list of research publications from the Quantum Information group please visit the federation page.

Theses
A fast polarization independent shifter of light. Ng Tien Tjuen (Honours thesis 06/07).

Towards a high quality 4-photon source. Lim Jiaqin (Honours thesis 06/07).
A narrow-band source for polarization-entangled photon pairs. Arpan Roy (Honours thesis 06/07).
Towards quantum key distribution in daylight. Caleb Ho (Honours thesis 06/07).
Optical Autocorrelation using Non-Linearity in a Simple Photodiode. Syed Abdullah Aljunid (Honours thesis 2006).

Efficient polarization measurement for quantum cryptography. Soo Kee Pang (Honours thesis 05/06).

Experiments with Multi-Photon states. Poh Hou Shun (Honours thesis 04/05).
Wong Ming Liang (Honours thesis 04/05).
Characterization of Entangled Photons via a Bell's Inequality. Peng Yun Han (Honours Thesis 04/05).
Foo Pei Yih (Honours thesis 2004).
Posters and talks
Spying on a quantum key distribution system through a timing side channel. Theory and Realisation of Practical Quantum Key Distribution, Waterloo, Canada. [Tropical QKD]. Poster, June 2007.
Free-Space Quantum Key Distribution using Polarization Entangled Photons. Theory and Realisation of Practical Quantum Key Distribution, Waterloo, Canada. [Tropical QKD]. Talk by Christian Kurtsiefer, June 2007.
Free-Space Quantum Key Distribution using Polarization Entangled Photons. Annual meeting of the Division of Atomic, Molecular and Optical Physics of APS, Calgary, Canada [DAMOP 2007]. Talk by Christian Kurtsiefer, June 2007.
Joint spectrum mapping of polarization entanglement in parametric down-conversion. Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference, Baltimore, US [CLEO/QELS 2007]. Talk by Hou Shun Poh, May 2007.
Free-space quantum key distribution using polarization-entangled photons. International Conference on Quantum Communication Measurement and Computing, Tsukuba, Japan [QCMC2006]. Talk by Christian Kurtsiefer, December 2006.
Joint Spectrum Mapping of Polarization Entanglement in Parametric Down Conversion. International Conference on Quantum Communication Measurement and Computing, Tsukuba, Japan [QCMC2006]. Poster, December 2006.
Optimal State Estimation Experiments for Photon Polarization. SPIE Optics and Photonics, San Diego, US. [SPIE O&P 2006]. Talk by Alex Ling, August 2006.
Experimental polarization state tomography using photon counting polarimeters. Alexander Ling, Kee Pang Soh, Antia Lamas-Linares and Christian Kurtsiefer, Proceedings of SPIE v. 6305, August 2006.
Quantum key distribution over large distances using entangled photon pairs. International Quantum Electronics Conference and Conference on Lasers and Electro-Optics Pacific Rim, Tokio, Japan. [IQEC/CLEO-PR 2005]. Talk by Ivan Marcikic, July 2005.
Preparation of Bell states with controlled white noise. International Quantum Electronics Conference and Conference on Lasers and Electro-Optics Pacific Rim, Tokio, Japan. [IQEC/CLEO-PR 2005]. Talk by Alex Ling, July 2005.
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