Abstract:In recent years, there has been a great effort to prove the security of quantum key distribution (QKD) with a minimum number of assumptions. Besides its intrinsic theoretical interest, this would allow for larger tolerance against device imperfections in the actual implementations. However, even in this device-independent scenario, one assumption seems unavoidable, that is, the presence of a protected space devoid of any unwanted information leakage in which the legitimate parties can privately generate, proce… Show more
“…The wavelength filter provides close to no loss at its central wavelength and approximately 80 dB of loss outside of this. By combining a small number of optical components – a 40 dB attenuator, 60 dB isolator and wavelength filter – sufficient total round trip attenuation can be achieved (on the order of 200 dB including component reflectivity) to make the possible information leakage from Trojan horse attacks negligible 21 .Figure 7Optical performance of ( a ) isolators and ( b ) wavelength filters, used to provide protection against Trojan horse attacks.
…”
Quantum key distribution’s (QKD’s) central and unique claim is information theoretic security. However there is an increasing understanding that the security of a QKD system relies not only on theoretical security proofs, but also on how closely the physical system matches the theoretical models and prevents attacks due to discrepancies. These side channel or hacking attacks exploit physical devices which do not necessarily behave precisely as the theory expects. As such there is a need for QKD systems to be demonstrated to provide security both in the theoretical and physical implementation. We report here a QKD system designed with this goal in mind, providing a more resilient target against possible hacking attacks including Trojan horse, detector blinding, phase randomisation and photon number splitting attacks. The QKD system was installed into a 45 km link of a metropolitan telecom network for a 2.5 month period, during which time the system operated continuously and distributed 1.33 Tbits of secure key data with a stable secure key rate over 200 kbit/s. In addition security is demonstrated against coherent attacks that are more general than the collective class of attacks usually considered.
“…The wavelength filter provides close to no loss at its central wavelength and approximately 80 dB of loss outside of this. By combining a small number of optical components – a 40 dB attenuator, 60 dB isolator and wavelength filter – sufficient total round trip attenuation can be achieved (on the order of 200 dB including component reflectivity) to make the possible information leakage from Trojan horse attacks negligible 21 .Figure 7Optical performance of ( a ) isolators and ( b ) wavelength filters, used to provide protection against Trojan horse attacks.
…”
Quantum key distribution’s (QKD’s) central and unique claim is information theoretic security. However there is an increasing understanding that the security of a QKD system relies not only on theoretical security proofs, but also on how closely the physical system matches the theoretical models and prevents attacks due to discrepancies. These side channel or hacking attacks exploit physical devices which do not necessarily behave precisely as the theory expects. As such there is a need for QKD systems to be demonstrated to provide security both in the theoretical and physical implementation. We report here a QKD system designed with this goal in mind, providing a more resilient target against possible hacking attacks including Trojan horse, detector blinding, phase randomisation and photon number splitting attacks. The QKD system was installed into a 45 km link of a metropolitan telecom network for a 2.5 month period, during which time the system operated continuously and distributed 1.33 Tbits of secure key data with a stable secure key rate over 200 kbit/s. In addition security is demonstrated against coherent attacks that are more general than the collective class of attacks usually considered.
“…Note that this framework analyses the effect of the phase modulator on the state. The effect of an intensity modulator, which is used in decoy-state QKD, is analysed in [22].…”
Section: Preliminary Notionsmentioning
confidence: 99%
“…This attack has previously been analysed by Lucamarini et al [18,22]. They assume that Eve uses a coherent state to probe the system, and describe using a one-way attenuating filter at the entry-point of Alice's apparatus as a defense.…”
The discrete-variable QKD protocols based on BB84 are known to be secure against an eavesdropper, Eve, intercepting the flying qubits and performing any quantum operation on them. However, these protocols may still be vulnerable to side-channel attacks. We investigate the Trojan-Horse sidechannel attack where Eve sends her own state into Alice's apparatus and measures the reflected state to estimate the key. We prove that the separable coherent state is optimal for Eve amongst the class of multi-mode Gaussian attack states, even in the presence of thermal noise. We then provide a bound on the secret key rate in the case where Eve may use any separable state.
“…Then apply a triangle inequality (5) to divide the security problems into two parts, as shown in (5)(6)(7)(8). 1 1 1 ABE ABE ABE ABE ABE ABE 2 2 2 tr tr tr…”
Section: Overview Of Trace Distance Security Criterionmentioning
confidence: 99%
“…On the other hand, numerous works have been made to remove real device imperfections from theoretical security proofs, such as MDI-QKD mentioned above, and Reference 6 to remove attacks on device imperfections. However, since 2009, H. P. Yuen, who theoretically discovered the squeezed state of coherent light 7 as well as the theories of M-ary quantum detection and parameter estimation 8,9 , has been warning that even the real devices work perfectly along the standardized theories, there are problems even in theories 10,11 .…”
In 2007, it was found that Known-Plaintext-Attack would reveal whole the string of the distributed key by Quantum Key Distribution (QKD) when the part of the plaintext was known to the eavesdropper, Eve, under the mutual information security criterion between Eve and legitimate users, Alice and Bob. To overcome, the trace distance criterion was introduced in the paper that the distance between the distributed quantum state and the ideal quantum state with Eve's quantum system decoupled from the quantum systems shared by Alice and Bob. On the other hand, Shor and Preskill proved in 2000 that entanglement-based QKDs are equivalent to prepare-and-measure QKDs, such as the first QKD, BB84. Their proof employed the mutual information criterion, therefore M. Koashi applied Shor-Preskill approach to the trace distance criterion in 2009. However, H. P. Yuen started criticisms on the security of QKDs from 2009, then completed his criticisms in 2016. He warned the security of QKDs are not sufficient. Furthermore, the trace distance would not provide "universal composability", which is supposed to guarantee Independent and Identically Distributed (IID) keys. He also proposed a new security criterion "Bit-Error-Rate (BER) guarantee," to evaluate the BER in the decoded message by Eve with her key close to the correct key. In this work, the author explains Yuen's criticisms and shows an example of the BER guarantee on BB84. Furthermore, the study revisits whether Shor-Preskill security proof approach really worked.
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