Randomized ancillary qubit overcomes detector-control and intercept-resend hacking of quantum key distribution

Abstract

Practical implementations of quantum key distribution (QKD) have been shown to be subject to various detector side-channel attacks that compromise the promised unconditional security. Most notable is a general class of attacks adopting the use of faked-state photons as in the detector-control and, more broadly, the intercept-resend attacks. In this paper, we present a simple scheme to overcome such class of attacks: A legitimate user, Bob, uses a polarization randomizer at his gateway to distort an ancillary polarization of a phase-encoded photon in a bidirectional QKD configuration. Passing through the randomizer once on the way to his partner, Alice, and again in the opposite direction, the polarization qubit of the genuine photon is immune to randomization. However, the polarization state of a photon from an intruder, Eve, to Bob is randomized and hence directed to a detector in a different path, whereupon it triggers an alert. We demonstrate theoretically and experimentally that, using commercial off-the-shelf detectors, it can be made impossible for Eve to avoid triggering the alert, no matter what faked-state of light she uses.

Quantum encryption, bidirectional quantum key distribution, detector control, intercept and resend attacks, faked state photons

References in corpus (17)

• Hacking commercial quantum cryptography systems by tailored bright illumination
• Quantum Eavesdropping without Interception: An Attack Exploiting the Dead Time of Single Photon Detectors
• Controlling passively-quenched single photon detectors by bright light
• After-gate attack on a quantum cryptosystem
• Breaking a quantum key distribution system through a timing side channel
• Squashing Models for Optical Measurements in Quantum Communication
• Avoiding the Detector Blinding Attack on Quantum Cryptography
• Thermal blinding of gated detectors in quantum cryptography
• Security loophole in free-space quantum key distribution due to spatial-mode detector-efficiency mismatch
• Security proof for QKD systems with threshold detectors
• Resilience of gated avalanche photodiodes against bright illumination attacks in quantum cryptography
• Reply to "Avoiding the Detector Blinding Attack on Quantum Cryptography"
• Real-time monitoring of single-photon detectors against eavesdropping in quantum key distribution systems
• Random Variation of Detector Efficiency: A Countermeasure against Detector Blinding Attacks for Quantum Key Distribution
• Hacking the quantum key distribution system by exploiting the avalanche transition region of single photon detectors
• Eavesdropper's ability to attack a free-space quantum-key-distribution receiver in atmospheric turbulence
• Robust countermeasure against detector control attack in practical quantum key distribution system