DocumentCode :
2170769
Title :
Calibration Attack and Defense in Continuous Variable Quantum Key Distribution
Author :
Ferenczi, Agnes ; Grangier, Philippe ; Grosshans, Frédéric
Author_Institution :
ENS de Cachan, Cachan
fYear :
2007
fDate :
17-22 June 2007
Firstpage :
1
Lastpage :
1
Abstract :
Quantum continuous variables (CV) have been explored as an alternative to qubits for quantum key distribution (QKD). More specifically, protocols using coherent states and homodyne or heterodyne measurements have been proposed and experimentally demonstrated (Grosshans et al., 2003). Relying on technologies allowing much higher rates than allowed by the single photon detectors used in qubit based QKD, those protocols are the only ones which could allow key rates in the GHz range in the foreseeable future. Furthermore, their security proofs have recently been extendend to generic attacks in the case of gaussian modulation. However, to our knowledge, all security analyses up to know have implicitely assumed Bob´s measurement setup to use a homo- or heterodyne detection with an external classical phase reference, while the experimental realizations use a lightbeam for this role. This beam doesn´t carry any information useful to the spy, and any attack on its phase could equally be carried on the signal beam. However, the intensity of this beam is used in experimental implementations to calibrate the quantum noise level. This calibration is then used to determine the channel gain, which is an important parameter of Eve´s attack. We show that this allows Eve to implement an intercepte resend attack forbiding QKD as soon as the losses are above 3dB. We also give simple countermeasures to this new class of attacks.
Keywords :
optical fibre communication; quantum cryptography; quantum noise; calibration attack; continuous variable quantum key distribution; quantum continuous variable; quantum noise level calibration; Calibration; Cryptographic protocols; Cryptography; Detectors; Information security; Noise level; Phase detection; Phase measurement; Photonics; Picture archiving and communication systems; Collective attacks; Continuous variables; Quantum cryptography; Unconditional security;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Lasers and Electro-Optics, 2007 and the International Quantum Electronics Conference. CLEOE-IQEC 2007. European Conference on
Conference_Location :
Munich
Print_ISBN :
978-1-4244-0931-0
Electronic_ISBN :
978-1-4244-0931-0
Type :
conf
DOI :
10.1109/CLEOE-IQEC.2007.4386772
Filename :
4386772
Link To Document :
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